Leonardo Times July 2015

LEONARDO TIMES Journal of the Society of Aerospace Engineering Students ‘Leonardo da Vinci’

25 YEARS HUBBLE

VSV Lustrum

The V 22 Osprey

‘Up, Up and Away’

A failed tiltrotor ?

AELS

Page 36

Page 56

Page 06 Year 19 | N°3 | July 2015

Interview

A little more room, a lot more comfort You’ll be amazed what extra legroom and a seat that reclines more can do for your journey. Get comfortable with Economy Comfort, available on all KLM ights.

Visit klm.com/economycomfort for more information.

From the previous issue ...

APriL 2015

EDITORIAL

extended one with almost twice the number of pages we usually have. Lustrums mark 5-year anniversaries of the founding of the society back in July 18, 1945. A special feature covers the events organized by the VSV to mark the Lustrum celebrations. The society has come a long way since it was established in the aftermath of the Second World War.

Leonardo Times Journal of the Society of Aerospace Engineering Students ‘Leonardo da Vinci’

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Putting the Wind in Wind Turbines

The student societies’ journal, the Leonardo Times, in its 19th year now, has become one of the leading journals of its kind, showcasing cutting-edge research carried out not just in the Netherlands, but also in rest of Europe and beyond. In the coming months, you will also be able to access the journal on your smartphones besides the regular print version. That’s right! We will be introducing a long-awaited version of the magazine online.

Apart from the regular articles featured in the print version, the website will be updated more frequently, covering latest happenings in the aerospace world.

“It’s the energy, stupid!”

On the cover of this issue, we feature the 25th anniversary of the iconic Hubble Space telescope. On page 40, you can read up on the history of the telescope, its journey through a quarter of a century and future plans. Apart from the new features, we have many interesting articles covering various aspects of Aerospace engineering. For instance, on page 56, you will find the Interview of the founder of AELS, a company that deals with aircraft endof-life solutions.

The title was already intriguing. I did not know if I should feel insulted or challenged so I started reading the article. I soon found out it was from the Materials department and once I laid aside my prejudices about this usually not too interesting field of engineering; I enjoyed this article a lot. It is fascinating to see that the solution for such a huge problem might be so simple.

Carmen Schulz

Urban Airspace Design

LOUPE

Observing the Earth as an Exoplanet

Year 19

number 2

ATM for extremely high traffic densities

cover 0415.indd 1

27/03/15 14:14

Dear Reader, This edition of the Leonardo Times Journal is special in many regards.

As promised in previous editions, we present to you the new design of the Leonardo Times.

The editorial team has also taken over the responsibility of creating a new layout in addition to the task of collecting interesting articles from across the world of Aerospace Engineering. It has taken the team over six months of deliberation to arrive at the new design. We have tried to put forward a modern, clean look in tune with the times. The Final editor of the magazine, Raphael Klein, has spent endless days learning and applying graphic design skills, and tweaking this edition.

To mark the new design, as well as the celebrations of the 14th Lustrum of our society, VSV ‘Leonardo da Vinci’, the July edition is an

I hope you, the reader, will appreciate the new design of the journal and I invite suggestions and comments regarding the articles that appear in the journal.

Sushant Gupta Editor-in-Chief

“The aftermath of disaster” “Nowadays, flying is considered one of the safest means of transportation.” After what recently happened (MH370, MH17 and Germanwings) a lot of people would disagree. The article is very good and illustrates very well what efforts are made to make flying safer. However, it would be nice if media could also state how safe flying already is.

Vick van der Broek

“Women in Aerospace” I like the fact that one of the editors of the journal wrote the column on the low number of female students in aerospace engineering. I strongly feel that we should strive for higher numbers of quality personnel in the field of engineering. The article was quite informative but lacked actual opinion that I would have expected from a female student at TU Delft.

Swasti Sudan

If you have remarks or opinions on this issue, let us know by dropping an email at: LeoTimes-VSV@student.tudelft.nl Leonardo Times editorial team 2014-15.

LEONARDO TIMES N°3 2015

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FRONT FEATURES 03 Editorial 07 Leonardo's Desk 12 In the News 16 Life after graduation

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CONTENTS

VSV Lustrum 'Up, Up and Away'

AERODYNAMICS 20 Large Eddy simulations of wind farms

AEROSPACE STRUCTURES AND MATERIALS (ASM)

Lustrums are the five-yearly celebrations of the founding of the VSV ‘Leonardo da Vinci’ on July 18, 1945. A look at the remarkable events organized as a mark of celebrating this momentous occasion.

24 AUDI: Progress through fibers 52 Self-healing of creep damaged steels 68 Designing new steels from scratch 72 Kissing Bonds

AVIATION DEPARTMENT 26 Symposium: Journey of a lifetime

CONTROL & OPERATIONS (C&O) 30 European airlines 70 Exploring human-like automation in ATM 74 Trans-Atlantic crossings

INTERNSHIP 34 Thesis at Rolls-Royce Deutschland 26

TIME FLIES 36 Bell Boeing V 22 Osprey

SPACE DEPARTMENT 40 25 Years of Hubble

40 25 Years of Hubble On April 24, 1990, the space shuttle Discovery lifted off from Earth with the Hubble Space Telescope nestled in its bay. Hubble was released into space the next day. Since that day, Hubble has reinvigorated and reshaped our perception of the cosmos and uncovered a universe where almost anything seems possible within the laws of physics.

FLIGHT PERFORMANCE AND PROPULSION (FPP) 48 How to train a pilot 64 High-fidelity propeller testing at DNW LLF 76 Aeronautics and liquefied natural gas

SPACE ENGINEERING 50 In pursuit of space debris

WIND ENERGY 62 Floating wind turbines 78 Optimizing for fluid-structure interaction AELS

COLUMN 81 Suicidal pilot at the helm

Interview AELS

ADVERTISMENTS 02 KLM 06 VSV Airshow 23 Hereema 33 ASML 41 Airbus Defence & Space 55 Thales 67 European Patent Office 83 NLR 84 Fokker

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"What happens with airplanes when they reach the end of their service life?”

Derk-Jan van Heerden, an alumnus of the Faculty of Aerospace Engineering, TU Delft founded a company: Aircraft End-ofLife Solutions (AELS) where he deals with this question everyday.

COLOPHON

How to train a Pilot

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YEAR 19, NUMBER 3, JULY 2015 The ‘Leonardo Times’ is issued by the Society for Aerospace Engineering students, the VSV ‘Leonardo da Vinci’ at the Delft University of Technology. The magazine is circulated 4 times a year with a circulation of 5500 copies.

ESA/NASA

To be able to fly a military aircraft, aspirants have to go through a tough selection process. Lt. Sebastian Blanke shares his experiences about his aspirations to become a military pilot in the Swiss Air Force.

SAF

EDITOR-IN-CHIEF: Sushant Gupta FINAL EDITOR: Raphael Klein EDITORIAL STAFF: Anita Mohil, Apeksha Amarnath, Bob Roos, Haider Hussain, Joris Stolwijk, Lubi Spranger Manfred Josefsson, Martina Stavreva, Victor Gutgesell, Vishal Latha Balakumar, Thom van Ostaijen.

THE FOLLOWING PEOPLE CONTRIBUTED: Arjan van Ettinger, Bas Verheugt, Mark Dekker, Rolf Boink, Ruud Gybels, Siddharth Ravichandran, Willem van Meerbeeck, Dhruv Mehta, Alexander Smits, Floris Heeres, Rens Douma, Lt. Sebastian Blanke, Ruub Bokdam, Bram Koops, Marco Gomez Jenkins, Maarten Gramsma, Kumayl Sarwar, Tomas Sinnige, Qi Lu, Wei Xu, Prof. dr. ir. Sybrand van der Zwaag, Carl Westin, Mirco Verze, Dr. Arvind Gangoli Rao, Jaco Brandsen, Dr. ir. Axelle Vire, Dr. Sergio Turteltaub and Prof. dr. Gerard van Bussel COVER IMAGE: NASA/ESA DESIGN, LAYOUT: SmallDesign, Delft PRINT: Quantes Grafimedia, Rijswijk Articles sent for publishing become property of ‘Leonardo Times’. No part of this publication may be reproduced by any means without written permission of the publisher. ‘Leonardo Times’ disclaims all responsibilities to return articles and pictures. Articles endorsed by name are not necessarily endorsed editorially. By sending in an article and/or photograph, the author is assured of being the owner of the copyright. ‘Leonardo Times’ disclaims all responsibility. The ‘Leonardo Times’ is distributed among all students, alumni and employees of the Aerospace Engineering faculty.

High-Fidelity Propeller Testing at DNW LLF Will the propeller make a comeback in the world of civil aviation? To pave the way, novel techniques for propeller noise reduction and efficiency increase were investigated in a two-week wind tunnel test at the Large Low-speed Facility of DNW in the Noordoostpolder.

VSV ‘Leonardo da Vinci’ Kluyverweg 1, 2629HS Delft Phone: 015-278 32 22 Email: VSV@tudelft.nl ISSN (PRINT) : 2352-7021 ISSN (ONLINE): 2352- 703X

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For more information, the website can be visited at www.vsv.tudelft.nl. At this website, the ‘Leonardo Times’ can also be digitally viewed.

Remarks, questions and/or suggestions can be emailed to the Editor-in-Chief at the following address: LeoTimes-VSV@student.tudelft.nl

LEONARDO TIMES N°3 2015

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LEONARDO’S DESK

'UP, UP & AWAY' Dear reader, As you are holding this edition of the Leonardo Times in your hands two things immediately catch the eye. Not only are you looking at an edition with a completely new, modern lay-out, it is also filled with an extraordinary amount of thought-provoking content. Before anything else, I would like to point out my strongest appreciation for the editors of the Leonardo Times for this fantastically designed edition, which would not have been possible without their excellent work.

Besides all articles concerning developments in aerospace, you will find a number of special pages dedicated to the 70th anniversary of the VSV ‘Leonardo da Vinci; our 14th lustrum.

They are specifically focused on the lustrum month of May, which was opened by an attempt of having 200 drones airborne simultaneously. More than 400 students watched while the VSV ‘Leonardo da Vinci’ performed its world record attempt. This was not the first time however. Over the course of its history, the VSV held or holds records in for example aircraft towing, the largest Mona Lisa ever painted and the largest paper aircraft (with a span of 14 meters) that ever flew. All these records were set in lustra, five-yearly celebrations of the founding of our society on July 18, 1945. Not only is a lustrum year a time of organising remarkable events but it is also a time of looking back on everything that our beloved society has achieved until now. And what would be a better place to do this than the lustrum edition of the Leonardo Times?

It all started with an excursion to the Salon d’Aéronautique in Paris. Shortly after, in honour of the 500th birthday of Leonardo da Vinci, a parachute to his design was thrown off the New Church in Delft with a dummy underneath. As a paper jokingly said: “Even though the unfortunate was equipped with a parachute, this particular way of dealing with members who won’t pay their fees will not benefit the name of the society”.

In the next lustrum, a KLM Viscount 803 was inaugurated with the name ‘Leonardo da Vinci’. Early in the morning, 50 members dressed in tailcoats pulled the aircraft out of the hangar. After the inauguration flight to Rome, the mayor of Vinci completed the official naming. Once more, an aircraft was named ‘Leonardo da Vinci’, but this time it was a KLM Boeing 747-300. The formalities were held at Schiphol Airport where the VSV and the KLM board inaugurated the Boeing. This time however, students did not pull the inaugurated aircraft out of the hangar; this one might have been too heavy!

During the fourth lustrum, a President of Honour was installed at the Extraordinary General Members Assembly, namely His Royal Highness Prince Bernhard. The honorary membership was granted to him by virtue of his stimulating activities for the aircraft industry and his great interest in aircraft manufacturing. During multiple lustra, he opened formal occasions such as symposia or air shows. Since the third lustrum, air shows have been organised almost every lustrum, sometimes attracting more than 30,000 visitors.

One last remarkable thing that I would like to share with you is the fact that the VSV founded two monuments. The first was placed in the second lustrum honouring the first motorised flight above the Netherlands near Ede. The second monument was inaugurated in The Hague during the third lustrum on the occasion of the first hot air balloon flight in the Netherlands. If you happen to be in the occasion, do not hesitate to stop by one of these stone structures celebrating Dutch pioneering in aviation.

These few examples only give a small glance of the rich history of our society but I hope it provides some insight in what can be achieved when you put a couple of future aerospace engineers together. Although the lustrum month is behind us, the 70th board still has some challenging projects to look forward to. Besides working on the long-term policy of the society during the summer, we’ll be putting our efforts in the freshmen weekend, the yearbook, the summer excursions and of course the VSV Seppe Airshow.

Please enjoy the new, elegant layout in front of you and do not forget: the details are not the details, they make the design.

With winged regards, Sjoerd van Rooijen President of the 70th board of the VSV ‘Leonardo da Vinci’

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EXTRAORDINARY GENERAL MEMBERS ASSEMBLY

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Schröder and Peters are wearing a space and flight suit, respectively, symbolising pioneers of the future. From the ramp hangs an enormous banner saying ‘VSV ‘Leonardo da Vinci’, 14th lustrum’. The lustrum will be officially opened today. Next to the banner, 70 helium balloons are attached to the ramp ‘keeping the platform in the air’. When the surrounding music slowly builds up and comes to a climax, the balloons are cut. While the lifting ramp slowly approaches the ground fire explosions and smoke make it a real spectacle to observe.

After the board officially greets the two gentlemen, they move inside, together with the crowd, where the inauguration will take place in the council room. Here, the president of the

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elft, 12 December 2014. The fly-overs of a Martinair Flight Academy Diamond and the Cessna Citation II business jet of the NLR and the TU Delft greet Martin Schröder and Michel Peters with honour. As the aircraft pierce through the clouds over the New Church, the two prospective Members of Honour are lifted up eight meters from the ground by a lifting ramp.

VSV ‘Leonardo da Vinci’ formally opens the lustrum by looking back on the rich history of the society and by shortly introducing the two future honorary members. However, the speeches of the two ‘youngest’ members of honour, Jacco Hoekstra and Jac Jansen, form the real introduction. From the speeches it appears clear that Mr. Schröder is one of the important aviation pioneers of the Neth-

erlands, while Mr. Peters works on the future of the sector by constantly innovating and improving the environmental impact of aerospace. After the blow of a hammer, both Martin Schröder and Michel Peters give their inaugural address. All attendants know that, once again, the VSV ‘Leonardo da Vinci’ can be very proud with their new members of honour.

LUSTRUM STUNT

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here is no better way to celebrate the opening of the lustrum month than with an event that is at least as spectacular.

On the first of May, the lustrum was honoured by a world record attempt at the very centre of the TU Delft campus. Students of all faculties were present to contribute to our attempt to launch and fly 200 drones at the same time.

The turnout exceeded 500 visitors, making the event a huge success.

With everything in place to guarantee an amazing day, even the weather contributed to a most pleasant and relaxed atmosphere.

The fields surrounding the Aula of the TU Delft were filled with students and drone-enthusiasts enjoying the spectacle. Some even dared to jump up to 10 meters high, using the bungee-trampoline that had been installed for the occasion.

The actual world record attempt provided an amazing sight of the campus. The official opening of the lustrum month and the countdown by president Sjoerd van Rooijen of the VSV and chairman Mats Dirkzwager of the UP’cie, was followed by flight of 200 drones, each piloted by an individual student. As the students launched their drones, it became even more evident that there was nothing to beat that moment. Afterwards, the students got to take home their drones as a physical reminder of the day and the lustrum of the VSV. Satisfied and joyful all students returned to their classes. The lustrum month had finally begun.

VSV

The organisational committee, dubbed UP’cie, managed to satisfy all attendees with a spectacular show including flame jets, free drones for all participants, free hotdogs and ice pops,

and even free sandwiches “Leo-nardo da Vinci”. The latter has been developed in cooperation with butcher Leo van Vliet, world-famous amongst the students in Delft.

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LUSTRUM OPENING PARTY

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VSV

or the start of our Lustrum month, the VSV ‘Leonardo da Vinci’ organized a weekend full of activities. After the Lustrum opening stunt and in between the preparations for the DeBaCo challenge “Met een zucht door de lucht”, the Lustrum Opening Party gave the Lustrum a kick-start!

Celebrating our lustrum is off course nothing without a good celebration party and that is exactly what was done. Together with the second year activities committee called the “AkCie” a lustrum opening party was hosted on the first of May at student discotheque the Lorre. With the theme “70 shades of blue” and the reveal of the 71th board of the VSV ‘Leonardo da Vinci’ it was expected to be great party. The party started with the tunes of DJ Tommy Smits who warmed up the audience for the presentation of the new board.

After the students had been in doubt for 2 hours, not knowing which group will guide the society next year, the 71th board of the VSV 'Leonardo da Vinci' was revealed consisting out of Matys Voorn – President, Karsten van Rest – Secretary, Geart van Dam – Treasurer, Lieke Lugtenborg - Educational Affairs, Martijn van Moorselaar - Career Affairs, Martijn Rozemeijer - Internal Affairs, Rosalie van Casteren -

the evening it can said that the lustrum opening party was a great success and a nice way of celebrating the 70th birthday of the society.

Hopefully the start of a memory that will last until the next lustrum!

significant distance. All of this changed when the senate took place on the ramp. With their years of aerospace knowledge they had created an aircraft, inspired by the Wright Flyer I. It turned out to be just as successful. After a quick acceleration down the ramp, she glided peacefully over the water to record distance.

It turned out this successful glide wouldn’t be outdone.

In the end of the day the AirCo went home with a hot air balloon flight for their creative design, and pilot Floris with a skydive for his spectacular flight. Everybody else went home with a lovely memory to this incredibly fun and successful event! One thing’s for sure, this weekend the 14th lustrum has been opened with a bang!

DEBACO

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he Design Battle Competition returned to a lustrum classic this year. To celebrate the 70th anniversary of the VSV ‘Leonardo da Vinci’, the DeBaCo organized ‘Met een zucht door de lucht’. Next to the Zuidkolk in Delft an 8-meter high ramp was built off which participating teams had to fly with their self-built airplanes. The team that would fly the furthest wins the incredible first prize: refueling F16’s in-flight from a KDC-10.

VSV

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External Affairs. After the revelation of the new board over more than 200 students enjoyed the smooth tunes of the DJ “LarryKoek”. And if this was not enough the DJ duo “de Gebroeders Scooter” turned the whole audience ecstatic with their 80s and 90s hits. Concluding

In the early morning of Sunday, May 3, the participants drove their vehicles in a parade from the building location to the ramp on the Hooikade, Delft. The sheer quality of their creations was astonishing. There were airplanes, delta wings, a helicopter and even a perfect copy of the lustrum caravan. Near the ramp, everything was ready as well. The ramp had been completed, the DJ had completed his sound check and all the foods and drinks were ready for the spectators. The dark sky above wouldn’t be able to withhold us from a great afternoon.

Around midday, it was time for the first aircraft to fly off the ramp. Caspar took place in his Luftwaffe inspired creation and made, after a gentle push over the edge, a very successful maiden flight. Some very creative vehicles followed, but none of them was really able to fly a LEONARDO TIMES N°3 2015

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ROSETTA, PHILAE AND THE COMET crevices, were shown. Then, an interesting animation of the trajectory of Rosetta around the comet was shown, including the trajectory that Rosetta completed in order to be able to place Philae at the projected spot, after which pictures of Philae approaching the comet and pictures of Philae’s landing spot were shown.

Feuerbacher concluded with expressing his hope that contact could be restored with Philae. After the lecture, there was the opportunity to ask questions, which was used very well. Mr. Feuerbacher skillfully answered the questions.

VSV

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n Thursday May 7, the first lustrum lecture took place. In the evening, 110 students and staff were gathered in Lecture Hall A for what was to be a very interesting lecture given by Prof. Dr. Berndt Feuerbacher about ESA’s Rosetta mission.

Feuerbacher, who studied Physics at the Ludwig-Maximilians-Universität in Munich, was project leader of this mission and initiator of the Philae lander that landed on comet 67P Churyumov-Gerasimenko on the 22th of November 2014.

Feuerbacher started the lecture by telling about comets and their characteristics. The difference between comets and asteroids, for instance, is that comets come from outside the solar system and thus only pass the sun once per many years while asteroids orbit the sun in more circular orbits, much closer to the sun. Furthermore Mr. Feuerbacher gave a short overview of all Rosetta’s equipment.

He continued with an explanation of the trajectory that Rosetta travelled in order to reach the comet, during which he showed some very nice pictures taken by Rosetta on which the comet came closer and closer. On the final ones, the comets coma was clearly visible and some much unexpected features of the comets surface, like boulders, cliffs and

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LUSTRUM GALA

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VSV

very five years, something special occurs. The tremendous amount of energy, work and enthusiasm that goes on in the society is centred which resulted in a year of unparalleled festivities. The lustrum year has the unique opportunity to organize larger,

more exiting and more audacious events. This lustrum year the “Galaxski” committee had the honour to organize the Lustrum Gala.

The Lustrum Gala, held on May 29 was the grand finale of the lustrum month. It is the event that is longed for and looked back upon for many years. It is the one time that the students of Delft, and in particular the VSV, classes up and leave Delft to spend the evening with their dates on an external location. And it was the very last time to celebrate the 70th year of the society.

For months the committee has been working on a number of things that together ensured a fantastic gala. After having found the perfect venue, the search began for the entertainment, which was found in a great live band and a DJ, who would continue until the early hours. Then, time was spent on the aspects that make this gala more exciting than any other gala that has taken place. In a typical Delft manner, an atmosphere was created that is both chic and invites to party. The location itself was something special as well. Eleven storeys high, overlooking the nation’s capital, every guest has experienced the perfect Up, Up & Away moment, as the sun set and the thousands of lights lit up the city centre of Amsterdam.

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EDUCATIONAL AND FUN FLYING WEEKEND

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an aviation-related film under the wings of our fleet of participating aircraft. To emphasize the educational aspect an extensive briefing will be held by experienced KLM pilots and air traffic controllers of Texel Airport. Throughout

the weekend participants can gain points with their team so that on Sunday the winner can be announced. Overall the goal is that everyone will go home with an enriched flying experience and memories of a fun weekend!

tional Airport and it is a continuation of the VSV Seppe Airshow in 2012, which attracted over 12,000 visitors and featured more than 25 flight demonstrations. Just like its predecessor, the VSV Breda Airshow 2015 will also

have free entrance for everyone and it once again proves to be a day filled with thrilling flight action and spectacle. Multiple national and international flight teams will be present to showcase the beauty of aviation, by performing stunning dynamic flight demonstrations with their aircraft. The Royal Dutch Air Force will even be present with an epic demonstration of their Apache Demo Team!

AIRSHOW

n the August 29, it is time for yet another beautiful edition of the air show: the VSV Breda Airshow 2015! The air show is organised by the VSV ‘Leonardo da Vinci’ in collaboration with Breda Interna-

FOTOBAZEN

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PIM VAN DAM

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n August, an educational and fun flying weekend will be organised at Texel Airport.

The weekend will start at the faculty with an exciting car tour passing several important aviation-related landmarks in Netherlands to subsequently end on the island of Texel. The next day the participants will be taken to the skies with small aircraft ranging from a Cessna 172 to a Piper Saratoga and a historic Tiger Moth. The flight will take participants on a ninety nautical mile journey past several iconic buildings they will have to recognize and over the beautiful ‘Waddenzee’ natural reserve area. Returning to Texel they will experience a variety of aircraft manoeuvres such as steep turns and a stall followed by a touch-and-go and full stop landing at the airfield. The ambition is to provide the members of the society with real flying experience to see theory coming into action first-hand. There is a confirmed cooperation of eight highly experience pilots for the entire weekend. The same evening the fifty participants will be able to share their experiences during a barbecue followed by a unique fly-in cinema. A large screen, some ten meters in diameter, will be constructed on the airport so that the participants can enjoy

The theme of this air show is ‘Dutch Powered Innovation in Aviation’, which will highlight the developments in aviation throughout history, with a particular focus on Dutch contributions.

Because even though the Netherlands is a small country, it has had quite some significant impact on aviation and you can learn all about it by visiting the air show! The innovation throughout aviation history will also be displayed with an exhibition of dozens of aircraft models, set up in a chronological static line.

Although aviation has developed tremendously throughout history, innovation is still a large factor in today’s aviation industry, as it creates the foundation of future aviation. Present and future innovations are therefore also important aspects of the VSV Breda Airshow, and they will also be highlighted in the static line. One example of future innovations on the air show is the presence of the PAL-V, which is one of the first vehicles that can be used both as a car and as an aircraft!

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IN THE NEWS ...

Crew Dragon’s pad abort test spacex.com

TYLER HICKS

May 6, 2015, Cape CanaveralSpaceX has yet tested another innovation, which aims at making manned space flight safer. The Pad Abort test was the dry rehearsal for the Crew Dragon’s launch abort system. This system poses another groundbreaking innovation for manned space flight. While traditional launch abort systems are mounted in a little tower on

top of the rocket, the Crew Dragon uses its eight Super Draco engines to fly off the rocket and rescue the crew, by recovering with a parachute. Traditional launch abort systems work only up until low altitudes. SpaceX new system however makes a launch abort possible until orbit is reached. The test went successful, looking at the fact that the system has

never been used. SpaceX used this opportunity to collect as much data as possible about the Crew Dragon. They put a dummy with sensors inside the capsule and after the test happily concluded that if the dummy was a person, he’d be perfectly fine. V.G.

Navy pilot’s death reflects hazards of the job nytimes.com May 11 2015, Washington DC All the US Navy recovered after Lt. Nathan Poloski’s fighter jet collided in midair with another Navy jet on a training mission in the western Pacific in September were his flight helmet and a few bits of debris. The 26-year-old pilot, who was deployed aboard the aircraft carrier USS Carl Vinson, died one month before the ship steamed into the Persian Gulf and began launching combat missions against the Islamic State. Lt Poloski’s body and his F/A-18C Hornet were never found in waters nearly three miles deep.

The other Hornet pilot was rescued after ejecting from his burning jet. Navy officials concluded that the crash shortly after takeoff was a tragic accident and assigned no blame.

The Navy’s top aviator concluded in his review of the eight-page accident report that the two

pilots, and several others in the vicinity, should have exercised more of what the military calls situational awareness — in this case, relying not only on an instrument-packed cockpit but also on looking outside to spot a looming catastrophe.

There were no onboard devices to warn the pilots of the impending collision. Controllers on the carrier were focusing on other jets that were landing. Investigators addressed the lack of situational awareness. “An overreliance on technology can be a disadvantage,” the report said.

The collision that killed Lt Poloski did not make any headlines, but it cast a spotlight on the elite Top Gun fighter pilot fraternity and their operations. H.H.

April 30, 2015 NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) space probe has ended its service by impacting the surface of Mercury. MESSENGER had been orbiting around Mercury since 2011 and had mapped the planet’s surface and measured its magnetic field. Its termination had been confirmed by the Deep Space Network Center in Goldstone, California, when they were unable to further detect MESSENGER’s signal. MESSENGER was the second man-made probe to visit Mercury, however the first to enter an orbit around it. After its eleven years of service, it seems that MESSENGER had just awoken our interest in Mercury. In the future JAXA and ESA are planning to send BepiColombo to an orbit around Mercury, to further study the planet. V.G. 12

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ESA

The end of MESSENGER space.com

SPACEX

Pluto, sharper than ever nasa.gov April 29, 2015 NASA’s New Horizons has started producing images of Pluto, which are better than Hubble’s. The nuclear powered probe was sent towards the outer rims of our solar system. It launched in 2006, flew by the moon shortly after, had another flyby at Jupiter in 2007 and is now approaching Pluto and its moons. New Horizons spent most of its journey in a hibernation mode. Woken up again, New Horizons’ instruments are now pointed towards Pluto and its moons to fulfill some of its primary mission objectives, which are e.g. to map the surface of Pluto, characterize its geology and search for other satellites.

were used to obtai the sharpest images of Pluto ever. The images and several spectroscopies suggested that Pluto has icy polar caps.

These polar caps might consist of frozen nitrogen. Animations show Pluto’s revolution about its own, highly tilted axis. The probe will continue to produce images of the Planet and its moons. As New Horizons approaches Pluto, the image quality will only increase and reveal further scientific findings about the dwarf planet.

After New Horizons’ flyby at Pluto, the probe will continue its journey away from our sun and towards the Kuiper belt, to study one or more objects. So far, it is the only spacecraft that is conceived to take a closer look at Pluto.

V.G.

SIKORSKY

Even though the probe is still millions of kilometers away from the dwarf planet, special equipment and image processing techniques

Preventing an impact

esa.int 4 April, 2015 ESA and NASA have started their collaboration on AIDA. The Asteroid Impact & Deflection Assessment aims at shooting a projectile like satellite at an asteroid.

Ultimately the project researches possible defense strategies in case an asteroid will actually be on collision course with Earth. NASA and ESA have chosen 2022 to impact an asteroid, which will come close to Earth. V.G.

GE runs firsts tests 3D-printed micro turbine

esa.int May 11, 2015 , Washington DC GE Aviation has run a 3D-printed micro jet turbine up to 33,000rpm, marking the first known test of a jet engine built using 3D printing. The project was revealed with a jet engine designed for the hobbyist, remote-controlled aircraft market.

The GE test comes more than two months after a similar project was revealed at the Avalon air show in Australia. GE has been among the most aggressive aerospace manufacturers to develop 3D printed parts. H.H.

Russia & China to heavy-lift helicopter

S-97 Raider first flight

defensenews.com

May 23, 2015 The Sikorsky S-97 Raider hit an important milestone Friday with the successful first flight of its experimental rotorcraft. The S-97, with two pilots, took off at the company’s West Palm Beach, Fla., facility about 7 a.m. and performed all of its proscribed movements over roughly an hour. The flight test took on the basics — among them three take-offs and landings, and movements in all cardinal directions at 10 knots.

The Raider is based on the X-2 technology

that Sikorsky developed in the late 2000s, but double the size at 11,000 pounds, with room for six troops for combat assault missions or extra equipment or ammunition.

Sikorsky pilot Bill Fell said the S-97 was “rock solid,” noting how little vibration or sound it produced, and how responsive it was. He and co-pilot Kevin Bredenbeck, spoke confidently about how different the S-97 is from a conventional helicopter and how impressed they are with its performance. H.H.

on

develop

flightglobal.com May 11 2015, Moscow Russian Helicopters and China’s state aircraft manufacturer AVIC have entered a framework agreement to develop a heavy lift helicopter. The AHL will have a takeoff weight of 38-tonnes, and be able to carry 10-tonnes internally and 15-tonnes on an external sling. It will be able to operate in all weather and terrain conditions. Key missions include transportation, medical evacuation, and firefighting. H.H.

Coffee for astronauts

nasa.gov 13 April, 2015, ISS CSR-6 was not just a resupply mission to the ISS. In its cargo was a new high tech device, designed by Lavazza and Argotec; the first space coffee machine, the ISSpresso. After being asked what food Luca Parmitano misses most in space, he replied “a real Italian espresso coffee”. Lavazza and Argotec must have taken this as an impulse to make the astronaut’s lives a bit more comfortable. V.G. LEONARDO TIMES N°3 2015

13

WIKIMEDIA

Laser cannon on ISS

riken.jp April 21, 2015, Japan Removing space debris is becoming more and more of an important task. Many ideas were proposed to clean space. These ideas go from trash collecting satellites to micro satellites, which attach to space debris. Now a proposal from Riken University in Japan suggests the installation of a laser cannon on the ISS, to shoot down space debris. The suggestion included a blue print of the machine, but is yet to be accepted. V.G.

FOKKER

fokker.com May 25 2015

MH370 Anniversary

theguardian.com May 13 2015 A year since flight MH370 disappeared, search teams continue to affirm their belief that wreckage will be found in the Indian Ocean. However, amid warnings over the timescale for the arduous, costly operation, there are signs that the determination to resolve aviation’s greatest mystery may be waning. H.H.

First female F-35 pilot begins training

aviationnews.eu May 7, 2015 The American Department of Defense welcomed its first female F-35 Lightning II pilot on May 5, 2015. Lt. Col. Christine Mau, 33rd Fighter Wing Operations Group deputy commander, completed her first training flight in the single-seat fifth-generation fighter following 14 virtual training missions in the Full Mission Simulator at the F-35 Academic Training Center. Mau acknowledged that although she may be the first woman pilot in the F-35 program, her gender has no bearing on her performance. She joked that the only difference between her and her fellow F-35 pilots is the size of her G-suit and facemask -- both extra-small. H.H.

Far far away galaxy

nasa.gov May 5, 2015, ISS Astronomers of Yale University and the University of California have broken the record for farthest away galaxy.

With the combined data of the Hubble space telescope and two more telescopes, the team confirmed the extremely luminous galaxy is the furthest away galaxy ever found. Observing this galaxy is not only something to break a record but can give clues on how the universe looked like in its early stages. The light of this galaxy, which is observed here on earth now is approximately 13 billion years old. V.G 14

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Airbus A400 crashes in Sevilla, Spain airbus.com May 9, 2015, Sevilla Spain The A400M aircraft was involved in an accident near Seville (Spain) Airport on May 09, 2015. The aircraft with the serial number MSN023, was making the first production flight and had departed from Seville Airport. The crash killed four of six Airbus employees aboard the military aircraft.

The other two Airbus employees on board are hospitalized and in a critical condition. Investigators, who recovered the plane’s black boxes soon after the crash, dispatched the two devices to a military facility outside Paris for

BLUE ORIGIN

Panoramic window for 737 BBJ

analysis, an investigator involved in the probe said. The crash resistant recording devices have sustained damage, though the investigator said the group was “confident” it could extract useful data. An Airbus Group go-team of technical advisors is being dispatched to provide full assistance to the official committee in charge of the investigation. The U.K., Germany, Malaysia, and Turkey temporarily halted A400M flights, though France said it would continue to operate the plane. H.H.

Blue Origin flight test blueorigin.com

April 29, 2015,Texas USA Blue Origin, another player on the commercial space travel market, has had its first successful test flight with its New Shepard spacecraft. Just like SpaceX, Blue Origin is all about sustainability. Their rocket and spacecraft is designed to be fully reusable. The rocket itself is a vertical takeoff, vertical landing system.

New Shepard flew to about 100km altitude, before separating from its rocket. The parachutes of the capsule fired just as planned and the capsule was thus recovered safely.

However, the rocket failed to recover. The plan was to have the rocket deploy drag increasing devices to slow down its decent and before reaching the ground, firing its main engine to land smoothly.

Jeff Benzon, founder of Blue Origin confirmed that during the flight test the capsule had separated “perfectly” from the rocket: however ,the rocket was lost during the test due to a hydraulic failure.

Blue Origin wants to continue its flight tests in the future. The company is already working on improving the hydraulic system of the rocket, to prove their reusable technology and maybe even beat SpaceX in having the first ever reusable rocket. In the future Blue Origin wants to sell regular short time flights to space with its New Shepard. The New Shepard can hold up to six passengers and offers about ten times the space for a person, as Alain Shepard had in his first Mercury flight. The capsule is even so spacious, that zero-G flying is possible. V.G.

Orion after the test nasa.gov

NASA

ESA

May 11, 2015, Huntsville, USA In early December 2014, NASA conducted its Exploration Flight Test 1 (EFT1) with its Orion spacecraft. The Orion was designed to bring astronauts further than LEO, to Mars and ultimately to an asteroid. The first manned mission of Orion is planned for 2021; this flight might include a circulation around the moon.

Today, however, Orion’s heat shield is being inspected. After EFT1, the spacecraft has carefully been recovered from the ocean and brought back to land. The heat shield went to the Marshall Space Flight Center, where it is being disassembled. More than 180 tiles are manually being removed for inspection. Most of them carry sensors inside, which need to be removed as well. This huge effort is being undertaken to find out about the behavior of the heat shield’s new Avcoat formulation. The material has previously been used in the Apollo command module. Orion’s next mission, Exploration Mission 1 (EM1), is scheduled for 2018. EM1 will send an unmanned Orion in a circumlunar orbit. Until then, the data of EFT1 will be used to further improve the spacecraft.

V.G.

NASA’s part chopper, part airplane cnn.com

May 14, 2015 NASA’S latest drone prototype, GL-10, better known as Greased Lightning, is an innovative new concept for a UAV from NASA’s Langley Research Center. The bat- tery-powered drone has a 3m wingspan, 10 electric motors and weighs 28kg at takeoff. It has a tilt-wing design that allows for vertical takeoff and landing - similar to existing tilt rotor aircraft. Successful flight tests have not only demonstrated its hovering capabilities during its vertical takeoff, but the team has also triumphed in some of the aerodynamically trickier situations. H.H.

CNES and DLR inaugurate altered gravity aircraft aviationnews.eu organize several campaigns every year, but for this inauguration, they joined forces. The parabolic flights complement ESA’s portfolio of gravity-science platforms, from hypergravity centrifuges to short-term zero gravity drop towers and sounding rockets as well as long-duration experiments that run on the International Space Station. French company Novespace has been running parabolic flights for more than 25 years flying from Bordeaux.

Last year they acquired their new aircraft to replace their trusty A300 – maintenance costs were growing due to its age. To turn it into a parabolic science aircraft most seats were removed to provide as much space as possible inside, while padded walls provide a soft landing for the passengers – the changes in ‘gravity’ can be hard to handle. Extra monitoring stations have been installed for a technician to oversee the aircraft’s systems while it is pushed to its limits. H.H.

NOVESPACE/CNES/DLR/ESA

May 11, 2015 ESA, France’s space agency (CNES) and the German aerospace center (DLR) inaugurated the Airbus A310 ZERO-G refitted for altered gravity by running 12 scientific experiments this week. Repeatedly putting the aircraft on an up-and-down trajectory angled at up to 50° creates brief periods of weightlessness. During the climb and pulling out of the descent, the occupants endure almost twice normal gravity. A person weighing 80 kg on Earth will feel as if they weighed 160 kg for around 20 seconds. At the top of each curve, the forces on the passengers and objects inside cancel each other out, causing everything to free-fall in weightlessness. Conducting hands-on experiments in weightlessness and hypergravity is enticing for researchers in fields as varied as astronomy, biology, physics, medicine and applied sciences, as well as for testing equipment before using it in space. ESA, CNES and DLR typically each

LEONARDO TIMES N°3 2015

15

TU DELFT

ALUMNI INTERVIEWS

LIFE AFTER GRADUATION

Interviews with former TU Delft aerospace student WILLIAM VAN MEERBEECK

Graduated in 09-2012

Which MSc track did you take and what was your thesis about?

I followed the master track “Space Systems Engineering”, because of my passion for space. I wrote my thesis at EADS Astrium in Munich, which dealt with the optimization of rocket nozzle contours over a large range of engine chamber pressures, mixture ratios and propellant combinations.

When you started studying Aerospace, what were your expectations for your future career?

I wanted to become a “rocket scientist”, so I hoped to work in a space company or space agency after graduating. That is why I chose the “Space Systems Engineering” master track, because it best fitted my interests.

Did it work out? What are you doing now, and where?

Yes, even better than expected. After my thesis, I had the opportunity to follow a 2-year graduate program at the European Space Agency. During these two very interesting years, I worked on the preliminary design of satellites as well as experimental work on fluid hammer phenomena in satellite feed lines. I currently work as an engineer at Swiss Space Systems (S3) in Switzerland. This young company has the objective to develop and operate unmanned suborbital space planes to 16

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launch satellites up to 250kg into orbit.

Describe a typical day at your current position S3 is a relatively small company with an ambitious objective, which means that everyone has a lot of responsibility. Everyone works on a part of the spaceplane, so my daily job deals with pure engineering and analysis of my subsystem, as well as frequent interaction with my colleagues from other disciplines, like aerodynamics or mission performance.

How are you applying your Aerospace knowledge at your current position?

My current position lets me apply my knowledge of space systems engineering on a daily

basis, so the master at TU Delft was a perfect fit. And since our spaceplane partly behaves like an aircraft, I also benefit from the other (aircraft-related) courses at Aerospace Engineering to understand the impact of my system on the complete design.

Which aspects of student life do you miss, and which aspects do you not miss at all?

What I miss most about my student life is the fact that you could do everything by bike.

With all the mountains in Switzerland, it is not as easy to do this. The exams every three months, on the other hand, I don’t miss that much.

BAS VERHEUGT

Which MSc track did you take and what was your thesis about?

Describe a typical day at your current position

I was part of the first cohort of the European Wind Energy Master (offshore track). I wrote my thesis for Siemens Wind Power in The Hague. I developed a MATLAB model to calculate the hydrodynamic loading on a jacket-based offshore wind turbine and consequently determine the structure’s response.

I spend most of the days in office in The Hague. The lion’s share of my work is performing load calculations, either pre-processing the input data or analyzing the results from the simulations. As there are many parties involved in the design process, I have a lot of contact with the project developer, foundation designer and certification body. Then there is the occasional trip to our colleagues in Denmark, the annual offshore trainings and of course the social activities.

When you started studying Aerospace, what were your expectations for your future career?

I didn’t know what kind of job I wanted; I hardly knew what was out there. I actually chose Aerospace Engineering because it is a hard, technical study with good job prospects in a wide variety of industries.

Did it work out? What are you doing now, and where?

It did. After my thesis, I got an offer to stay at Siemens Wind Power in The Hague to join the team of Offshore Load Engineers. I was happy to accept as the job provides a good mix between engineering work and managing your own part of the project. My main task is to determine forces and moments based on environmental conditions (wind, wave, soil) for design purposes of an offshore wind turbine.

I do this in an informal environment, working in a team of young, motivated people (mostly from TU Delft).

SIEMENS

Graduated in 11-2014

How are you applying your Aerospace knowledge at your current position?

An offshore wind turbine is a product from many different fields of engineering. During my studies, I have learned several relevant topics, such as aerodynamics (BSc) and hydrodynamics (MSc). I apply my theoretical knowledge to assess the results of the simulations. All in all, my studies have prepared me well for my current job but there is also still a lot to learn.

Which aspects of student life do you miss, and which aspects do you not miss at all?

Even though we have pretty flexible working hours, I miss the freedom to plan your own time. Work is done during the week and social activities are for the weekends. This took

some getting used to but I must say that it is also very relaxing to wake up on a Saturday without the nagging feeling that you should actually be studying ...

ARJAN VAN ETTINGER

Graduated in 12-2014

EXXON

Which MSc track did you take and what was your thesis about?

I did the Control & Operations (ATO) track and for my thesis I made a multi-agent based analysis to study how the situation awareness of the avionics and flight crew affected decision making in the accident of Turkish Airlines at Schiphol in 2009.

When you started studying Aerospace, what were your expectations for your future career?

Of course I wanted to design rockets and fighter jets when I started studying Aerospace Engineering but I soon found out I wanted to do more than sitting behind my computer analyzing data or modeling stuff. I did really enjoy the analytical thinking; problem solving and working with other engineers, so that was also what I wanted in my career.

Did it work out? What are you doing now, and where?

It sure did! I’m working as a Machinery Engineer for ExxonMobil in Rotterdam. My main task is to revalidate the long-term operating and maintenance strategies of critical equipment. It’s a combination of scenario identification; risk analysis and mitigation with the goal

to further improve safety, reliability and financial performance of the site. Very interesting!

Describe a typical day at your current position Every day is different! Today started with putting on all my safety gear and going outside to check critical equipment and interview operators that work with it. The rest of the day I spent on my equipment strategy project. I discussed the best way to mitigate certain risks with my colleagues and started on a presentation for management.

How are you applying your Aerospace knowledge at your current position?

When I work on turbines or compressors I get to apply some thermodynamics, but it is all very practical. Because of the complexity of equipment, the level of thinking is still very high - and at times even higher - but a lot less theoretical.

Which aspects of student life do you miss, and which aspects do you not miss at all?

Of course, I miss the tremendous freedom you have as a student but I got a challenging job and great colleagues for it in return! I had a lot of fun while studying so I guess the only thing I don’t miss at all are the red numbers on my bank account at the end of the month.

LEONARDO TIMES N°3 2015

17

MARK DEKKER

Graduated in 08-2014

I chose the aerodynamics track and did my thesis on the analysis of a novel concept for sailing boats taking into account the interaction between the flexible sailcloth and the airflow. Sailing seems like a field that still has a lot to gain from modern aerodynamic theory and tools like CFD.

When you started studying Aerospace, what were your expectations for your future career?

I actually did Mechanical Engineering in my Bachelors hoping to design cars one day.

During that time, I found out more about aerodynamics and got really interested in it. Especially flow visualization and the colorful CFD images got me interested. Once I started my Masters, I realized that the challenging work in applied vehicle aerodynamics happens in motorsport and supercar design, so that became my dream job.

Did it work out? What are you doing now, and where?

It did work out! While doing my internship at BMW I worked with a small motorsport and supercar design firm called KLK Motorsport.

They are a small team of engineers designing supercars, concept cars, and support the mo-

torsports teams of the big German car manufacturers such as Audi, VW, Lamborghini and BMW. Luckily for me, they were looking for an aerodynamicist just as I finished my degree and the rest is history.

Describe a typical day at your current position Since most big flow simulations run overnight, I have a look at the results in the morning when I get in. Then, depending on the phase of the project a large amount of time is either spent on documenting insights and concepts or new concepts and optimization studies need to be designed and set up to achieve more gains. A lot of the work also includes programming scripts for automation. The rest of the time can be spent on research for a new concept or meetings.

VIVA F1

Which MSc track did you take and what was your thesis about?

How are you applying your Aerospace knowledge at your current position?

I wouldn’t get very far through my day without the aerospace knowledge. I’m always surprised how much I refer back to the things I learned in the Bachelors. That is the kind of practical knowledge that is really helpful to remember, especially when speaking to engineers with different specializations.

Which aspects of student life do you miss, and which aspects do you not

miss at all?

I miss having time. It is no secret; working in motorsport requires you to put in long hours.

On the plus side, I am very happy that I no longer need to write long reports that nobody really wants to read and it is very nice not to have to live on a student budget anymore.

SIDDHARTH RAVICHANDRAN

Graduated in 10-2012

My MSc track was Aerodynamics, and my thesis was in the area of Experimental Fluid Dynamics and Plasma Flow Control. It involved using different geometrical configurations of Plasma Actuators at the trailing edge of a bluff body to suppress vortex shedding. The thesis was thrilling, not least because of the cool toys I got to play with: Wind Tunnels, PIV and High Speed Cameras and Plasma Actuators that operated at 40kV.

When you started studying Aerospace, what were your expectations for your future career?

To be honest, since my previous academic background was in Physics and Mechanical Engineering. I wasn’t terribly familiar with Aerospace Engineering. When I started at Delft, I took up the Aerodynamics track at Delft as I was very interested in Wind Energy and wanted to work in that field. However, my love of physics, mathematics, and experimentation pushed me in the more fundamental direction of fluid mechanics.

Did it work out? What are you doing now, and where?

As the Brits would say, I suppose it didn’t work out too badly! I’m currently working at Rolls18

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Royce Plc in the UK. I joined the graduate program in early 2013, and spent the next 18 months working in different technical departments within the Civil Aerospace Division on Large Civil Engines such as the Trent XWB and Trent 1000. I’m off the scheme now and working full time as a Turbines Design and Stress Engineer in Derby.

Describe a typical day at your current position I currently work as designer and stress engineer on a project involving novel manufacturing techniques for turbine components. As a stress engineer, I work on ensuring the physical integrity of the parts within their operating regimes on the basis of FE modeling and analysis. Additionally, there is a lot of hands-on involvement and support to Engine Testing and Manufacturing, as well as a wealth of training courses that the company encourages participation in.

How are you applying your Aerospace knowledge at your current position?

The engineering insight and ‘common sense’ that I use on a daily basis on an almost unconscious level was definitely learned during the study. Other notable attributes that come to mind are analytical skills, general awareness and familiarity around measurement systems and a fundamental approach to problem

EUROPEAN-AVIATION.NET

Which MSc track did you take and what was your thesis about?

solving rather than reliance on computational tools.

Which aspects of student life do you miss, and which aspects do you not miss at all?

Off the top of my head, I’d say that I miss the freedom and flexibility of student life. What I don’t miss is being broke and cocooned from the outside world in a university bubble!

ROLF BOINK

Graduated in 03-2014

Which MSc track did you take and what was your thesis about?

I did the track Control & Simulation, in which I specialized myself into Human-Machine interaction. My thesis was about the haptic guidance interface for car driving, as developed in a mutual effort between Aerospace and Mechanical Engineering. The objective of my research was to understand and reduce conflicts between drivers and the haptic shared controller.

When you started studying Aerospace, what were your expectations for your future career?

My expectations were to find a job in anything that I would like to do after studying. Aerospace Engineering gives you an engineering degree that covers many aspects of modern technology and that is of high quality.

Did it work out? What are you doing now, and where?

It did work out. After graduation, I decided that the best thing for me was to work in a field that had to do with boosting renewable energy into the existing energy landscape. Also, it was important for me to find an employer that cares about society and human beings.

These two requirements are combined for me in the Technical Traineeship in Liander, where

I started a year ago. Liander is the grid operator for the electricity and gas grid in parts of the Netherlands.

Describe a typical day at your current position

By May 1, 2015, I went back to my roots, when I started as an Interface Engineer for the new Liander Control Room. A typical day now is rather atypical; absorbing all the information that is available already. I just started as part of the project team that represents all the important disciplines.

How are you applying your Aerospace knowledge at your current position?

In this new job, I will have to apply all my knowledge about human-machine interaction, human factors, ecological interface design and simulations that I gained during my track Control & Simulation. I see a cockpit in an aircraft essentially as a very fancy, lightweight and flying type of control room.

Which aspects of student life do you miss, and which aspects do you not miss at all?

What I miss of my student life is the freedom and the time to go deeper and deeper into all sorts of subjects that you like to think about.

What I don’t miss are the moments, in which I had two third of a month left and the money on my account had already gone.

RUUD GYBELS

Graduated in 10-2014

I did ATO profile in the Control and Operations track. My thesis was about the prediction of aircraft flyover noise by using semi-empirical prediction methods.

When you started studying Aerospace, what were your expectations for your future career?

I started studying Aerospace Engineering because I had an interest in technology in general. Especially the hands on approach with projects implemented in the curriculum triggered me to go study in Delft. One of the things I thought about back then was becoming an aerodynamicist in the automotive industry.

Did it work out? What are you doing now, and where?

It absolutely went differently. After getting my Bachelors and taking business courses for my honors track at the University of Texas in Austin, my interest shifted to a business-oriented career. After my graduation, I started working for Dell in Amsterdam.

I am in the graduate program of Dell. This is a one-year program, with two rotations of six months. During my first half year, I was doing a quality improvement project. Right now, I just started my second half-year in a sales role, in which I have to convince IT partners to start selling Dell solutions to end-customers. It is really challenging and interesting to have contacts with so many different people and to be adaptable in how to treat these different personalities.

How are you applying your Aerospace knowledge at your current position?

If you work at one of the world’s largest IT vendors, then you do not apply any typical aerospace knowledge. However, I experience that my analytical skills and the ability to think very quickly in concepts and solutions helps me to achieve my daily goals.

DELL

Which MSc track did you take and what was your thesis about?

Which aspects of student life do you miss, and which aspects do you not miss at all?

The flexibility you have in your daily planning; in my student’s days, it was not a problem to study in the evening instead of the morning.

That’s not possible anymore since I have to serve customers during office hours.

Describe a typical day at your current position LEONARDO TIMES N°3 2015

19

WIND ENERGY

LARGE EDDY SIMULATION OF WIND FARMS

Numerical Experiments with Energy-Conserving schemes

Dhruv Mehta, PhD Candidate, AWEP, Faculty of Aerospace Engineering, TU Delft To predict the power produced by a wind farm, one must at least know the velocity of the air flowing through the farm. The wind velocity can be measured using meteorological masts with devices that can assess wind speed and direction a given point or even over a limited area. However, this data is not enough to study complex flow phenomena like gusts, kinetic energy transport, and the effect of the wind farm on local weather. This article explains the challenges involved in complementing experimental data with that from simulations.

A

wind farm consists of a cluster of wind turbines placed over a piece of land or at sea, that work together to produce electricity from the wind. The wind turbines are generally placed in a manner that leads to efficient generation of electricity. For example, one programs the turbines’ control systems to make the turbine face the wind as the latter changes direction, because the amount of power a turbine can extract from the wind is proportional to the cube of the wind speed.

Further, the control system must also be able to switch the turbine off when the wind speed is too high to allow safe operation. Such tuning is required to reduce the higher cost of maintenance, while ensuring longevity. Thus, prior to a wind farm’s establishment, one must perform a thorough study of the farm’s design 20

N°3 2015 LEONARDO TIMES

and placement, while aiming not only to maximize power output but also the operational life of a turbine or the farm as a whole.

To perform such a study, one must have good knowledge of the flow of air through a wind farm, a subject that is known as wind farm aerodynamics. The reason being that whilst a turbine is in operation, it extracts energy from the air and produces a wake that bears a velocity lower than that of the undisturbed atmospheric flow. In most cases, as a turbine’s wake travels along the length of the wind farm, it interacts with downstream turbines, which results in the latter being exposed to slower air with a lower potential for generating power. A wind farm can have over fifty turbines, providing ample chances for turbine-wake

interactions and also wake-wake interactions, all of which can affect the local flow velocity, leading to reduction in power.

Additionally, the lower wake velocity or available energy is accompanied by a concomitant increase in turbulence. Turbulent flows show rapid fluctuation in velocity and pressure, which leads to an increased transport of momentum and energy, especially if the flow is dominated by inertia or its viscosity is too low to dissipate any increase in momentum transport through turbulence. Upon interaction with turbines, these fluctuations increase the loading on the turbine and reduce its longevity. Further, fluctuations could also lead to resonance that reinforces the turbine’s vibrations, which could lead to structural failure.

To avoid a detailed aerodynamic analysis, one could simply place the turbines far apart to avert any turbine’s wake from interacting with another turbine. However, this demands more area, which adds to the costs in terms of land, connecting cables that would relay the electricity produced and also increases the

SHUTTERSTOCK

costs of maintenance. Alternatively, turbines of different height can be used. But the earth’s surface creates the atmospheric boundary layer that has a lower velocity close to the surface. Placing turbines of different heights would mean that the shorter ones generate less power due to the slower oncoming air, while the taller ones may be exposed to wind speeds greater than what they could bear.

Therefore, an aerodynamic analysis on the entire wind farm is very desirable.

Aerodynamic data can be gathered by placing suitable apparatus on masts within a wind farm. But due to measurement equipment interfering with the flow, on can only place a small number of masts that are not enough to provide detailed information at a resolution that would allow tracing every wake and determining the velocity field at most relevant locations on a farm. Further, the erratic nature of the atmosphere only hampers the analysis of data as one can never be certain if what is being measured downstream of a turbine is solely due to the turbine’s activity alone and is free from gusts that occur frequently, a wake interaction from another turbine, etc. Thus, scientists now resort to the simulations to determine how wakes develop and interact. Simulations seek to model the wind turbines and the atmospheric boundary layer mathematically with an accuracy that is enough to resolve the wakes and their interactions. However, simu-

lations rely greatly on the numerical schemes used for modeling the flow, i.e., solving the Navier-Stokes equations and the availability of computational resources that determines the level of accuracy that one can achieve.

Of the above, the current project deals with the development of numerical schemes and flow models that are not only accurate but demand relatively lesser computational effort.

A turbulent flow, like that through a wind farm, comprises of various regions of swirling flow known as eddies. These eddies vary in size across the flow field and their velocity fluctuations are generally correlated in both, space and time. In short, the presence of obstacles at one part in a flow alters the velocity field, which by virtue of eddies, is felt in other regions of the flow, depending on the size of the eddies and strength of the disturbance. Further, the higher

Surfaces of constant vorticity coloured by stream wise velocity juxtaposed with slices depicting the stream wise velocity, on a model wind farm.

LEONARDO TIMES N°3 2015

21

the flow’s Reynolds number, or the molecular viscosity’s inability to control the effect of disturbances, the greater is the range of eddies.

On a wind farm, these eddies range from nearly a kilometer in size to those of a few millimeters created by the grass over the surface, for instance. A thorough analysis would obviously involve modeling all possible eddies in a flow, a technique known as Direct Numerical Simulation (DNS). DNS is computationally expensive and nearly impossible for a wind farm given the range of eddies.

As an alternative, one models only the larger eddies that carry most of the flow’s mass, momentum and energy, and which mainly interact with the turbines and are carried by the wakes. In short, one must analyze the flow as discrete volumes, which should be small enough to provide an accurate representation of the flow’s energy but large enough to not lead to a high number of parcels such that their analysis is made impossible. This technique is known as Large Eddy Simulation.

Like every numerical code, the discretization of the flow into small volumes needs mathematical approximations; similar to how one uses the trapezoidal or the Simpson’s rule to approximate the area under a curve. Discretizing a flow and hence the Navier-Stokes equations is rather complicated. At times, numerical schemes go awry to the extent that they themselves end up influencing the development of the flow, rather than just predicting it. With regards to a wind farm simulation, poor numerical schemes can lead to wakes with abnormally high or low velocities, and the same for turbulence, leading to a faulty power and load prediction. This can mislead designers trying to optimize how a wind farm must be established.

Decay of a Taylor-Green vortex at a Reynolds number of 1600. The gradients in the initial velocity field at t = 0 cause the individual vortices to stretch (see t = 3). Excessive stretching of the vortices leads to their breakdown producing continually smaller and smaller vortices. Red patches indicate regions with the highest kinetic energy and the blue with the lowest.

This project aims at developing numerical schemes that while solving the Navier-Stokes equations do not spuriously affect the flow’s evolution. Of the various schemes that can

do this, this project uses energy-conserving schemes. An energy-conserving scheme ensures that the flow’s energy is only altered by physical processes like dissipation through viscosity, forcing through wind turbines etc., and not spuriously through numerical approximations that lead to faulty velocity fields. Apart from their ability to resolve the flow accurately, these schemes are numerically stable even if the discretization is very coarse. This enables faster yet reliable calculations. These energy-conserving schemes are being developed as part of the energy-conserving Navier-Stokes solver at the Energy Research Centre of the Netherlands. Once ready, these schemes will help simulate wind farms with an accuracy that is sufficient to determine the power that a wind farm can produce and also the loads that the turbines encounter while doing so, thus enabling the design of more efficient and long-lasting wind farms.

References

A detailed simulation of a single wind turbine showing how the wake (blue) is relatively slower than the atmospheric flow (red). The green blobs are Isosurfaces of Q-Criterion that represents regions dominated by vorticity over simple shear. These vertical structures are not only produced by the turbine-atmosphere interaction but also through the atmospheric boundary layer that grows over the ground (Reproduced from www.nrel.gov) 22

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D Mehta, AH van Zuijlen and H Bijl, “Energy-Conserving schemes for Wind Farm Aerodynamics”, Journal of Physics Conference Series, 2014.

D Mehta, AH van Zuijlen, B Koren, JG Holierhoek and H Bijl, “Large Eddy Simulation of Wind Farm Aerodynamics: A Review”, Journal of Wind Engineering and Industrial Aerodynamics, 2014.

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ASM

AUDI: PROGRESS THROUGH FIBERS

The right material in the right amount at the right place

Alexander Smits, MSc Student ASM Chair, Faculty of Aerospace Engineering, TU Delft

The most commonly used material for the body of a modern automotive vehicle is steel. Typical steel alloys show excellent stiffness and strength characteristics and also a rather high density compared to other structural materials, resulting in a relatively high body weight. The weight of a car has a profound influence on its performance, including fuel consumption, handling and crash safety. Therefore, lightweight solutions are imperative.

T

o save weight, Audi has developed a full aluminum body named the Audi Space Frame (ASF). This type of body debuted in the first generation Audi A8 limousine, launched in 1994. The aluminum body was not only lighter than the equivalent steel variants, but it also offered a higher torsional rigidity. The same kind of body was later also used in the Audi A2, TT and R8. In more recent years, Carbon Fiber Reinforced Plastics (CFRP) have been introduced into high-end consumer cars. These materials are generally lightweight and offer attractive strength-to-weight and stiffness-toweight ratios over traditional structural materials such as steel or aluminum. For the second generation Audi R8, launched in March 2015, Audi first introduced CFRP in structural parts of the body. Amongst others, the B-pillars, the central tunnel and the rear wall are made from carbon, making up almost 30kg of the 199kg weighing frame (see visual). Compared to an equivalent full aluminum frame (in terms of stiffness and safety requirements), the new multi-material space frame is approximately 15% lighter.

In order to get the most out of composite materials, Audi has embarked a research program to design and manufacture composite parts with a non-conventional layup. Currently, a third master thesis project on this topic is focusing on implementing this technology into an actual car part with corresponding load case and boundary conditions. Due to the confidential nature of this project, no description of the part under investigation or details of the design process can be given.

VARIABLE STIFFNESS COMPOSITES Traditionally, composite laminates are made IJSSELMUIDEN

When developing composite parts, a different design philosophy is needed; one cannot

simply convert an existing metallic design to a part made from fiber-reinforced plastics.

Especially in the automotive industry, cost is an important factor. Composite parts will be expensive compared to metal parts, especially when manufacturing processes and design (both geometry and layup) are not considered carefully. Minimizing the assembly cost and time, minimizing the use of rivets and other attachments, and integration of parts can reduce cost.

from stacked layers with uniform fiber angle orientation throughout each layer. Most often, the stacking sequence of a laminate is designed to be balanced (for every +θ layer there is a –θ layer) and symmetric (laminate mid-plane is an axis of symmetry) while at the same time the possible orientations are limited to 0°, 90° and ±45°. These restrictions on the layup result in a limited design space. This has the advantage that layup optimization can be done (relatively) quickly with discrete optimization methods such as genetic algorithms.

Fiber-reinforced composites are anisotropic; mechanical properties such as strength and stiffness are functions of the fiber orientation.

When using straight fibers in combination with a traditional layup, these anisotropic properties are not fully exploited. Modern fiber placement techniques have in-plane steering capabilities, which allow for the placement of curved fiber paths. Continuously varying fiber orientation angles result in a non-uniform layup and consequently a varying stiffness distribution. Composites with this type of layup are often reverted to as Variable Stiffness (VS) composites.

OPTIMIZATION OF VS COMPOSITES

Figure 1 - Schematic overview of the developed multi-step optimization approach 24

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Allowing the fiber orientation to vary within a layer results in a practically unlimited number of possible layups. For the design of VS composites, IJsselmuiden proposed a three-step optimization routine in his PhD thesis (IJsselmuiden, 2011). The forthcoming optimi-

the different stages should be ensured in the design process. The method of combining multiple segments can also be used to combine curved fiber paths with a traditional layup.

This allows for the blending of variable stiffness parts with a conventional constant stiffness part without the need of a joint between the two parts.

BLOM

AG AUDI

TAILORED FIBER PLACEMENT To show that VS composite parts can also be produced, a prototype has been manufactured. One of the manufacturing techniques that can be used to manufacture composites with curved fiber paths is Tailored Fiber Placement (TFP). TFP is a dry fiber placement technique based on industrial embroidery machines and was developed by the Leibniz Institute of Polymer Research in Dresden (IPF) in 1992. Some of the advantages of tailored fiber placement are: zation tool can be used to find an optimum set of lamination parameters per design point for a given load case and boundary conditions (Figure 1: Step 1). From these lamination parameters, the true fiber architecture can be found with a genetic algorithm (Step 2). The developed MATLAB-based VS optimization algorithm was used by master students of the AS&CM group during a series of projects at the Audi Lightweight Design Centre.

Amongst other things, the VS optimization tool was coupled to MSC Nastran to allow the optimization of more complex structures. The last step in the three-step optimization routine is the fiber path construction. For this step, several methods exist. A fairly accessible method to describe curved fiber paths is the curvilinear fiber path parameterization as introduced by former AS&CM professor Z. Gürdal (Gürdal and Olmedo, 1993). To increase the design flexibility, a part can be divided in multiple stages/segments as shown in Figure 2 (Blom et al., 2008). Of course, fiber continuation between

1.

2.

3.

4.

Series production possible due to high level of automation; Near-net-shape production of 2D preforms reducing the amount of waste material; A high production rate compared to other fiber placement technologies High flexibility in orientation of fibers.

With TFP, a single roving made of carbon, glass or other types of fiber material is continuously placed and stitched to a substrate/ base material. Figure 3 shows a sketch of the working principle of TFP (Fristedt, 2012). The base material and roving pipe/needle move in a synchronized, stepwise manner to create a zigzag stitch pattern relative to the fiber.

The stitching head, including the roving pipe and needle, can rotate 360° for optimal flexibility. Current FTP embroidery machines can make up to 800 stitches per minute (Mattheij, Gliesche and Feltin, 1998). To further increase the production rate, multiple TFP machines can be placed in line. Preforms made with

Figure 2 - Multi-stage angle variation TFP allow for impregnation with Resin Transfer Moulding (RTM). This semi- to fully automated resin injection process is often used for small to medium volume series. Also, the (structural) CFRP parts of the new Audi R8 and its sibling, the Lamborghini Huracán, are impregnated with this technology.

EVALUATION AND OUTLOOK With the described method, the layup of an actual automotive part has been optimized.

Without changes to the geometry or the number of layers, the (calculated) performance increased by up to 30% compared to a traditional layup.

It has been shown that it is possible to design, optimize and manufacture a variable stiffness composite automotive part and that this can be done in a cost effective way.

Audi has the philosophy that for optimum functioning, parts should be made from the right material in the right amount at the right place. Implementing variable stiffness composites can be a way to pursue this idea and could allow Audi to bring its composite parts to the next level.

References [1] IJsselmuiden, S.T., “Optimal Design of Variable Stiffness Composite Structures Using Lamination Parameters”, PhD thesis, Delft University of Technology, 2011.

[2] Gürdal Z. and Olmedo, R., "In-plane response of laminates with spatially varying fiber orientations - Variable stiffness concept", AIAA Journal, Vol. 31, No. 4 (1993), pp. 751-758.

[3] Blom, A.W., Setoodeh, S., Hol, J.M.A.M. and Gürdal, Z., “Design of variable-stiffness conical shells for maximum fundamental eigenfrequency”. In: Computers & Structures 86:9 (2008), pp. 870–878.

[4] Fristedt, T., “Novel Fiber Placement Technologies for Composite Applications”. Tailored Fiber Placement, SPE ACCE 2012. 2012.

[5] Mattheij, P., Gliesche, K. and Feltin, D., “Tailored Fiber Placement - Mechanical Properties and Applications”. In: Journal of Reinforced Plastics and Composites 17:9 (1998), pp. 774–786.

Figure 3 - Sketch of TFP principle LEONARDO TIMES N°3 2015

25

AVIATION DEPARTMENT

JOURNEY OF A LIFETIME SYMPOSIUM

The cycle of aircraft development

Floris Heeres, BSc. Student Aerospace Engineering, Symposium Affairs of the 22th Aviation Department For the 14th Lustrum of the VSV ‘Leonardo da Vinci’ the Aviation Department had the honour of organizing the annual symposium. This year’s theme was ‘Journey of a Lifetime – the cycle of aircraft development’. On March 3rd, a record-breaking number of 601 Aerospace Engineering students and professionals from the aviation industry participated in this symposium. Moreover, eight speakers from such a wide variety of facets of the aviation industry was a first.

W

ith this symposium the audience was taken on a journey through the entire life of an aircraft through the three main life phases: design and production, operational life, and engineering, maintenance and end-of-life. With these three main life phases as a basis, the audience was given an insight into the various aspects that define an aircraft’s life. The Chairman, Anne Cor Groeneveld, did an excellent job in linking all the different topics together into a coherent story. The aim of this symposium was to broaden the view of the visitors, to inspire the next generation of aerospace engineering students and to raise questions that would spark new innovations in the aviation industry.

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DESIGN AND PRODUCTION The day started with the topic ‘Design and Production’ where aircraft and engine manufacturers of both commercial and military aircraft gave an insight into their companies and the challenges that they are facing.

Axel Flaig, senior vice president research and technology of Airbus kicked off the day. He shared his and Airbus’ ideas on future market opportunities with respect to aircraft design.

Airbus’ main goals for the future are to decrease the noise, CO2 and NOx emissions together with an increase in efficiency. On the long run, this means disruptive new concepts

and configurations have to be developed.

However, currently, Airbus is mainly focused on incremental innovation in their derivative products, for example the A320neo and the new A350. Mr. Flaig believes virtualization will be the key to ensure the maturity of future concepts.

Increasing the overall efficiency of aircraft could not be achieved without the advancement of their propulsion system. The next speaker, Ric Parker, director of research and technology at Rolls Royce, discussed this subject in more detail. The topic of his lecture was: ‘The Future of Large Civil Aircraft Propulsion, Evolution or Revolution’. Like Axel Flaig from Airbus, he emphasized the process of evolution of their current Trent engine. However, this evolution is limited. Another big focus lies on open rotor engines. In the more distant future Rolls Royce may be focusing on recuperated and inter-cooled engines; hybrid and electric propulsion; and fully distributed propulsion

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systems. As a conclusion, Ric Parker wanted to raise attention to, currently science fiction like, technologies that might be used in the future. For example, beamed energy, laser propulsion and space tethers.

The last speaker in this part of the programme was Michiel van der Maat. He is Vice President of the defense programs of Fokker Technologies and President of the Netherlands Industrial Fighter Aircraft Replacement Platform (NIFARP). From his experience in these positions, he gave an interesting presentation on the participation of Fokker in the JSF, F-35, programme and the importance of this programme for the Netherlands. The participation of Fokker in this programme triggered numerous innovations that will also help improve Fokker’s products for the civil aircraft market.

Looking back at the content of the three lectures in the Design and Production part of the day, some general conclusions can be drawn.

Nowadays, the general layout of an aircraft is essentially always the same. However, as the presenters pointed out, to reach the goals for the reduction of emissions set by ACARE, disruptive designs will have to be made to replace the conventional aircraft design. Although there was a consensus among the

speakers that this would happen, they could not agree on when this would be taking place.

What was also evident from that morning’s lectures was that especially batteries and subsequent hybrid propulsion systems would be game changing technologies in the future development of aircraft.

OPERATIONAL LIFE Design and production of an aircraft could take decades, but when an aircraft is eventually flying, it requires attention in numerous fields, both on the ground and in the air, to successfully fulfil the operational life phase. In this section of the day, an airline, an airport and an air traffic control body discussed the challenges they encounter in keeping an aircraft flying.

Michiel van Dorst, Executive Vice President Flight Operations of KLM, gave an interesting presentation on the efforts of KLM for their pilots to be multi-licensed for the B777 and the B787. The possibility to have their pilots fly both these aircraft makes the airline more flexible in the flight planning, more efficient in crew assignment and generally more cost efficient.

KLM went through an extensive process of making this licensing completely safe, even beyond the requirements set by EASA. During the discussion at the end of the presentation

the question arose for the second time that day what the thoughts were on unmanned flight. Like his predecessor of the day Axel Flaig, Michiel van Dorst told the audience that efforts would be made towards unmanned flight, but that this will go step by step. The first step would be to fly with fewer pilots in the cockpit and increased monitoring of the alertness of the pilots. Subsequently, freighter aircraft will probably fly without pilots and then eventually, if the customer trusts the technology, passenger aircraft will follow.

Next up was Miriam Hoekstra-van der Deen, Director of Airport Operations of Schiphol Group. She told the audience about the outdoor facilities at Schiphol Airport that make sure aircraft can use the airport efficiently.

These facilities include the runways, baggage systems and gates, but Schiphol Group also provides the snow patrol- and bird control units. As aircraft size and shapes change continuously, Schiphol also has to change to remain capable of accommodating all aircraft in the future. They are making plans to expand their current A pier in order to be able to handle more passengers and to be flexible with larger aircraft in the future.

The first speaker after the lunch was Paul LEONARDO TIMES N°3 2015

27

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Sjoerd van Rooijen, the current president of VSV, opening the symposium.

Riemens who is the CEO of Air Traffic Control in the Netherlands (LVNL) as well as the chairman of CANSO, an organisation with the mission to transform the global air traffic management system. He started his presentation by posing the audience a question. “Does air traffic control in the future need more air traffic controllers or engineers?” With this question as a basis, Mr. Riemens elaborated on the process of making the global air traffic control system simpler and more decisive. The LVNL wants to achieve this by assigning every aircraft with a 4D trajectory in the future. This will require more engineers who are able to generate these 4D trajectories and manage the surrounding systems. For the Netherlands specifically, the LVNL is creating a shared border area with Germany that will make it possible for aircraft to fly more directly, saving time and fuel.

There are many aspects related to the operational life of an aircraft. The approaches that Michiel van Dorst, Mariam Hoekstra-van der Deen and Paul Riemens took towards the operational phase were very diverse, but they did provide some similar insights. Sustainability is an important issue along the whole spectrum of the aviation industry, along with efficiency.

In the operational phase, a sustainable approach is required to ensure a better overall use of aircraft and to use resources such as fuel, people and money in a more efficient

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manner. KLM aims to make their pilots multi-licensed in order to efficiently use their aircraft and the people operating them. For Schiphol, sustainability is of key importance in the design of their facilities, such as the new A terminal.

LVNL contributes to the enhanced efficiency of operations by effectively planning the route of an aircraft in 4D and by continuously looking for ways to improve the system.

ENGINEERING, MAINTENANCE AND END-OF-LIFE The final phases of an aircraft’s life were discussed in the last part of the day, ‘Engineering, Maintenance and End-of-Life’. Many look upon this phase as the end of the journey of an aircraft. However, it is also the beginning of a new life. The final two speakers spoke about both aspects of this life phase.

Managing Director of Arkefly, Hans van de Velde, explained the challenges his company has encountered in being the first airline in the Netherlands to introduce the B787 Dreamliner. These were challenges in maintenance, future planning and operations. The 787 Dreamliner is Boeing’s latest aircraft; it is mostly made of composite materials and uses significantly more software applications. Maintenance on a 787 is not done using a hammer or screwdriver. Technicians use a tablet and often a software update is used to fix a problem. The 787 has been flight tested significantly, but

there is still quite a lot of uncertainty about the performance of the composite material after a significant amount of flight cycles.

The final speaker of the symposium was former Aerospace Engineering student, founder and managing director of AELS - Aircraft End of Life Solutions, Derk-Jan van Heerden. His lecture on what happens to aircraft that are no longer fit to fly provided the audience with a topic that is very uncommon in the Aerospace Engineering curriculum. Moreover, judging from the expressions of the many professionals present in the room, they too were intrigued by the topic. AELS dismantles and disassembles aircraft. It takes care of the component management and recycling of the scrap materials. Mr. Van Heerden elaborated on the need for proper end-of-life solutions for aircraft and how this business will develop in the future with the increasing number of aircraft reaching their end of life around the world.

A development that has rather recently become more pronounced in the development of aircraft is the use of carbon fibre based composite materials. This means that the use of this material is also relatively new within the areas of engineering and maintenance, but it will definitely have its impact. A great example of how maintenance has to be adapted to these new developments is that of Arkefly.

The VSV symposium “Journey of a Lifetime” reached its final destination, after a journey that started eight months ago for the organizing committee. During this symposium, the audience was taken on the same journey an aircraft will take several decades to complete.

The symposium would not have been possible without the help of all the professionals that challenged us to develop new ideas on the content of this symposium, and all the people who helped out during the day itself, all of whom we would like to thank for their contributions.

Anne Cor Groeneveld, Chairman, Dutch Aviation Group and Axel Flaig, Senior VP, research and technology at Airbus, discussing questions. future. This coupled with his anecdotes on the past, especially on the Dakota DC-3: the beauty of that aircraft, the music it produces and the revolution it was at that time. All of this resulted in an overview of the whole life cycle of an aircraft.

One of the main goals of this symposium was to educate the audience and to give them answers to question they might not have thought about. However and more importantly, it is always important to value the questions that were not answered, the ideas that were generated and the inspiration that flourished in young Aerospace Engineering students as well as all the professionals present during this symposium.

This is where the journey starts.

The Aviation Department The aviation department of the Society of Aerospace Engineering Students ‘Leonardo da Vinci’ fulfills the needs of aviation enthusiasts by organising activities like lectures and excursions in the Netherlands and abroad.

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Eight speakers shared their vision on the future of aviation, all from their respective backgrounds. Chairperson Anne Cor Groeneveld smoothly intertwined the different topics and phases of the day. Further, she also gave her view on the events arising now and in the

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They have to approach the maintenance of their new Boeing 787’s in an entire different way than their existing mostly conventional metal aircraft. Different methods of detecting and repairing damages to carbon fiber structures are available, but gaining experience in their usage and developing new methods is still an on-going process. The aircraft that currently feature these carbon fiber structures are very new, and hopefully will not reach their end-of-life phase very soon. However, when they do, new methods will have to be applied to properly dismantle these aircraft and to reuse the scrap material. As of today only clean production, waste can be recycled. The question remains how well both the maintenance and end-of-life procedures can be adapted to the changes that are currently being made to the designs of new aircraft.

Hans van de Velde, Managing Director of Arkefly, explaining the challenges the company has encountered in being the first airline in the Netherlands to introduce the B787 Dreamliner.

LEONARDO TIMES N°3 2015

29

AF-KLM

C&O

EUROPEAN AIRLINES

Low cost vs legacy carriers

Raphael Klein, MSc Student, Faculty of Aerospace Engineering & Editor, Leonardo Times Since the advent of low cost airlines in European Skies, the Airline industry has seen fierce competition. On point-to-point short haul flights, low costs carriers have bled legacy carriers dry. On long-haul services, these same low costs operators are breaking their teeth trying to enter a market, which is owned mostly by well-established legacy carriers.

T

he European aviation market is a very dynamic environment. It is composed of a multitude of airlines, most of which are old national flag carriers, challenged by their own lack of flexibility and new low cost airlines. The sky is littered with failed airlines such as Sabena or Swissair, faltering airlines such as Corsair, AF-KLM, Alitalia or Lufthansa, and flourishing airlines such as Iberia or Ryanair. Contrary to common perception, most flag carriers are not facing doom or have been defeated by low cost carriers yet. Their respective governments politically, and sometimes financially support them. However, their positive prospects are mostly due to their own upcoming difficult restructuring, c.f. Iberia, Lufthansa and Air France-KLM. Recently, oil prices have dropped leading to large reduction in costs for most airlines (though some of them couldn’t benefit due to long term hedging commitments). Finally, most European airlines have large orders for new fuel-efficient aircraft that should help to further reduce their overall costs in the coming years.

IBERIA AND IAG The most spectacular turn-around of the past years in the airline industry is in the case of Iberia. In two years, the company that had previ30

N°3 2015 LEONARDO TIMES

ously lost more than $1 billion over a five-year period, posted a profit in the first nine months of the year 2014. This came at heavy cost for the employees of Iberia. A massive restructuring plan, the “Plan de Futuro” intended to cut a lot of jobs. The plan further implemented salary reduction across the board and massive lay-offs. It was accompanied by the replacing of the most fuel inefficient aircraft used on the trunk routes such as the A340-200, the introduction of new fuel-efficient A330, and the upcoming A350, for which the deliveries will start in 2015. Finally, the company introduced new products, reduced fairs, and focused their product to their area of expertise: South America.

The airline turned Madrid Barajas airport into their hub and the European (and Chinese) gateway to the southern continent. Until now, Europe remains the most used route to South America for Asian airlines. Iberia is now using its short-haul subsidiary Iberia Express to redirect all flights to Barajas and direct passengers to Europe’s largest airline to South America.

Thanks to these strategies, Iberia is retaining a 42% capacity share in Madrid for hub operations. Iberia is also battling successfully against Ryanair in Madrid for domestic oper-

ations by providing differential price products on Iberia express and using another IAG subsidiary Vueling, the low cost arm of the group.

Vueling and Iberia combined accounted for 55% of the domestic capacity in 2014 in Madrid leaving Ryanair at a meager 18% share in fourth position behind Air Europa.

RYANAIR’S INFLUENCE ON LEGACY CARRIERS Although Ryanair has to fight hard to win over Madrid Barajas, it has had a very large impact over the last year on all legacy carriers throughout Europe. Ryanair has quickly become the biggest European low-cost airline. It is now operating an all Boeing 737-800 fleet of three hundred aircraft with three hundred additional orders, including 100 Boeing 737 MAX 200 as a launch customer. Ryanair transported over 81.7 million passengers in 2014, a growth of three percent year on year.

But it was not always such a smooth ride for Ryanair. A few years back, the company was navigating through one of its biggest crisis in its history. Headline news covered incidents such as the company refusing to change a passenger's ticket even though his father had died, or Ryanair refusing to refund a passenger ticket as he had died “too soon” before the flight. Ryanair also got itself in trouble in France where the airline was fined heavily for giving Irish contracts to its employees at its Marseille base.

After a strategy reversal from the top man-

agement of Ryanair, the company introduced a large overhaul of its customer relation by reducing fees for additional bags, re-training flight crews, and introducing new business oriented packages (priority boarding, free airport check-in etc.). Ryanair has also been know to operate from remote airports to limit their airport fees - think of Paris Beauvais which is more than one hour from Paris by bus. Recently, Ryanair launched several routes from Brussels National Airport, which is significantly closer to Brussels than the so-called Brussels South Charleroi Airport. This was both due to Brussels National airport doing its best to attract Ryanair and by Ryanair trying to attract more business travellers trying to land as close as possible to Europe’s capital.

This year, Ryanair announced a large expansion of its bases. It recently opened bases in Berlin, Copenhagen and Bratislava. By now, Ryanair operates on 72 bases across Europe with a dense network of 189 destinations.

Finally, Ryanair has started to consider establishing a base in Amsterdam Schiphol or Lelystad when it expands. Ryanair then hopes to conquer one of the last European markets they left untapped with a current meager market share of around 4% in the Netherlands.

LONG-HAUL LOW COSTS CARRIERS Low costs airlines are not succeeding everywhere though. Long-haul routes have remained a mystery for Ryanair and have become a burden for Norwegian Air Shuttle, another very large low cost airline operating predominantly out of Norway. Although Ryanair recently announced its upcoming offer for long-haul flights (backtracking on it days later), Norwegian has been operating low cost long-haul flight based on its brand new B7878 out of its Irish registered subsidiary to the North American market and Thailand.

Norwegian Air Shuttle is having a hard time on long-haul services for several reasons.

The first is what legacy carriers are notoriously known for: hub operations. Norwegian, like most low costs airlines, does not have a feeder network for its long haul operations. It is therefore having a hard time filling its planes, which are significantly larger than short haul B737. Furthermore, to establish proper service to its destination, the airline must have a regular schedule to the cities it serves which makes it even harder to fill the planes to load factors comparable to profitable short haul operations. This problem is there to stay although a solution would be to build feeder networks or to invest in small narrow body aircraft such as the planned A321neoLR or the rumored B737-8ERX. These aircraft can carry significantly less passengers while allowing airlines to bridge the East coast of the United States to Europe.

Norwegian Air Shuttle is also weighed down by other factors. The first is that most long haul flights land at International airports with high landing and airport fees. This is because night noise restrictions are much lower in such airports compared to smaller airports, where some night flights are forbidden. Furthermore, they also have to face increase in crew costs that have to fly at night or stay overnight in distant cities, not able to return home before the end of their shift. These costs have a significant impact on profitability. This of course does not mention the fact that some passengers are not prepared to spend 12 hours on flights without access to any food (without WIKIPEDIA

One of the first companies to attempt low costs flights was Air Asia X, which tried to bridge the gap from Asia to Europe using cheap flights. It ended pretty badly and Air Asia

X discontinued all its flights to Europe. Oasis Honk Kong Airline suffered the same fate. Air Asia X is currently trying to restart its entire program using more fuel-efficient aircraft such as the A330neo for which they placed 50 orders.

Norwegian is attempting the same feat and is, so far, having the same luck as Air Asia X. This year marked the first year the Norwegian company was in the red, weighed down heavily by its new loss making company.

Norwegian Air Shuttle B787-8.

additional fees), and with extra luggage fees in often referred to “cattle” class seating arrangements.

LEGACY CARRIERS It is not on long-haul flights that legacy carriers feel threatened by low costs airlines like Norwegian Air Shuttle and Ryanair. It is on short-haul point-to-point operations that they have done most damage. This is the case for KLM, Air France, or Lufthansa, and before the restructuring, for Iberia as well. AF-KLM, and Lufthansa are particularly touched by the expansion of low cost carriers. Recently, these three carriers have been in the news for the unprecedented strikes disrupting their activities. For Air France, these strikes stem from the “Transform 2015” plan while for Lufthansa, it came from the “SCORE” restructuring plan.

France is notoriously known for its strong unions but recently Lufthansa has been dealing with even more strikes. These numerous strikes pit the pilots against the company’s need for restructuring. The company is asking to raise the retirement age of pilots and to reduce their benefits after they retire. The company has, so far, refused to yield as it sees this restructuration plan as vital to its effort to remain profitable although the strikes are costing millions. For Air France, the two weeks historic strike in October 2014 has managed to keep the company in the red for its 2014 activities with an estimated loss of 500 million euros just due to the strike. This was a large dent in Air France’s results that would have been positive, if not for the strike. KLM on its side remained marginally profitable.

The Transform plan for AF-KLM is also badly received by the unions. The main point of discontent, besides dismissing close to 2,800 employees, is Transavia France, the new low cost arm of the company. This subsidiary was designed to counter the rise of Ryanair, EasyJet, Vuelling or Norwegian, albeit a little late. AF-KLM aims at replacing point-to-point flights on the legacy carrier main airlines (Air France and Hop!) and moving them onto Transavia. This would see a growth of Transavia on point-to-point travel by 120% from 2012 to 2017, while leading to a reduction on Air France and Hop! by 40%. The main reason behind this strategy is that AF-KLM is only making money on long haul operations and wants to keep its short haul flights mostly for hub-feeding operations (Figure 1).

Transform 2015 called for the larger growth for the French arm of Transavia (the Dutch Transavia is already comparatively well developed), and with it, the new contracts for the pilots. The pilots assigned to the low cost company would receive much lower benefits than their colleagues in Air France or Hop!.

Transform also plans on the opening of bases around Europe for Transavia similarly to Ryanair. This has also become a point of friction between the airline management and unions as the unions are accusing the airline of plan LEONARDO TIMES N°3 2015

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Lufthansa has a similar strategy to AF-KLM. It is important to remember that Lufthansa remains Europe’s largest airline and owns airlines such as Swiss, Austrian or a large part of SN Brussels Airlines. Most importantly, Lufthansa owns its own low cost carrier: Germanwings. The problems in Germany are similar to those at AF-KLM. Lufthansa wants to significantly expand the operation of its low-cost subsidiary, which would mean contract renegotiations with the pilots and other personnel. This has led to over ten strikes in 2014 and so far in 2015 more than 2 one-day strikes. Current benefits for Lufthansa pilots are for example the right to retire at 55 and to retain a large part of their salary until their official retirement at age 65. Lufthansa is pushing to raise this retirement age. Lufthansa is also trying to build Germanwings in small entities spread around Europe to avoid large union formation that could threaten its profitability when restructuring is required.

COMPETITION FROM UAE The bleak picture painted above for both AFKLM and Lufthansa is not all that the airlines fear. Beside the low-cost front, there is the long haul competition from the Middle East: Qatar Airways, Emirates and Etihad Airways. These three companies have seemingly endless pockets allowing them to grow at never seen rates and conquering most of Europe’s destinations. Beside this, the big three can also use to their advantage the Open Skies agreement.

This allows the big three to stop in Europe for refueling and continue onwards to the United States; providing a direct threat to all European legacy carriers. Emirates is already doing so through Milan to New York.

Lufthansa new B747-8I. Airways. This could have an impact on the European market and Qatar could establish more operations at both London Heathrow and Madrid Barajas. The impact of these investments is yet to be seen.

THE FINANCIAL SIDE All is not doomed for European legacy carriers. The current dip in oil prices has helped relive the pressure on most airlines, although some of them lost a lot of money due to hedging practices. As the oil prices stabilize at a much lower point than it was just a year ago, airlines’ main cost factor is about to decrease sharply. This allows more leeway on their restructuring and maybe softening the blow.

Besides this, most European legacy carriers are heavily investing in new generation aircraft that are much more fuel-efficient. The A340s are being phased out across Europe and so are the older B747s. KLM recently retired the MD-11 for similar reasons. AF-KLM, Lufthansa, Iberia, British Airways all invested in the newly built A350 and B787, allowing them to open longer routes with much more fuel-efficient aircraft.

CONSOLIDATION It is hard not to remember what happened in the United States a few decades back, and AF-KLM

Beside the threat of losing market shares, Qatar is slowly buying in European airlines. Qatar Airways owns significant shares in Alitalia, Air Berlin and recently bought a 10% share into IAG, which is the owner of Iberia and British

AVIONERS.NET

ning to open bases in countries where benefits are significantly lower (E.g. Portugal and Czech Republic).

which continued up to last year. The United States airline sector was busy with hundreds of airlines: small and big fighting for survival. After years of struggle consolidation, and Chapter 11 episodes, the United States has been left with only three major airlines: American Airlines, Delta Airlines, and United Airlines.

Considering the ongoing churning in the European aviation market, it is hard to expect anything but the same in Europe considering the way industry matures. But Europe is different from the United States. One of the biggest differences is the omnipresence of states in legacy carrier affairs. A lot of countries want their own legacy carriers to keep on carrying the name of the country they represent. Furthermore, other elements as simple as languages differences can show that inter-country solidification might not be the best way onwards. The differences between Air France and KLM have been caused, in some parts, by the language difference between the two companies, the French being notoriously reluctant to speak in English. This has caused unnecessary friction in a company busy restructuring itself. These problems are however not known to be an issue within the Lufthansa group. Could this be because Austrian, Lufthansa and Swiss all speak German?

What will happen in the coming years could very well define the future for European Airlines. The impact of the different restructuring plans will give some insight on what to expect and whether we can expect the downfall of some of the largest legacy carriers for better or for worse.

References http://www.journal-aviation.com/ http://www.aspireaviation.com/ http://leehamnews.com/ http://www.emirates.com/ http://centreforaviation.com/ http://www.klm.com/corporate/en/about-klm/ air-france-klm/ https://www.germanwings.com/ http://www.ryanair.com http://www.theguardian.com/business/2015/ mar/19/

Figure 1 - Transform 2020 presentation slide.

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CHRISTIAN DRAGHICI

INTERNSHIP

THESIS AT ROLLS-ROYCE DEUTSCHLAND

Living in the vibrant city of Berlin

Rens Douma, MSc Graduate Aerospace Engineering, Aerodynamics Last year, I spent 10 months in Berlin working on my thesis project at the nacelle aerodynamics group of Rolls-Royce Deutschland, the German division of the well-known engine manufacturer Rolls-Royce. Apart from the challenging work this project had to offer, I was also eager to discover how living in the German capital would be like. the accuracy and applicability of various intake test configurations to a real crosswind scenario, by carrying out a CFD study and comparing the results with available experimental data. In Delft, I started with a thorough

FRANK M. RAFIK

R

olls-Royce Deutschland, the German division of the engine manufacturer Rolls-Royce, develops and manufactures aircraft gas turbines, mainly for small and medium range civil aircraft and corporate jets.

A full development and manufacturing site is located in Dahlewitz, about 20km south of the city of Berlin. The BR700 family of turbofans is developed here, which powers (amongst others) the Boeing 717, Bombardier Global Express and Gulfstream V and 650 aircraft. The company is furthermore involved in the development and manufacturing of the TP400-D6 for the Airbus A400M military aircraft and the V2500 for the Airbus A320. In March 2014, I started in Dahlewitz with my thesis work at the nacelle aerodynamics group. I decided to move to Berlin and take a public transport card to commute to Dahlewitz, as the site was easily reached by public transport. Nine months of compelling thesis work and living in an exciting city were about to begin.

THE PROJECT WORK After the application process was completed, I received the assignment description. The main objective of the thesis was to improve 34

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literature study and I quickly discovered the broad scope of the project and the various flow effects involved with creating flow distortion in the intake. From the consulted similar literature, I listed the most appropriate CFD turbulence models to predict the flow effects.

After I eagerly started on-site in Dahlewitz, I got to learn all the ins and outs of applying CFD on complex industrial geometries. Since I had to do every aspect of the CFD solution procedure, including Computer Aided Design (CAD) modelling, meshing, choosing repre-

One of the many street art murals in Berlin.

RENS DOUMA

The Rolls-Royce BR710 aircraft engine in the Berliner Technikmuseum. My worked involved a similar engine. sentative boundary conditions, solving and post-processing, I got to learn a wide variety of software packages. I also became used to the special kind of time management CFD engineers use, as most simulations took one or multiple days to converge to a solution. Sometimes the first thing that I saw on my computer screen on Monday morning was a crashed simulation that I initiated the Friday afternoon before, convinced that it would run smoothly over the weekend to deliver nice results. After hours of CAD modelling, numerous discarded meshes and hundreds of CFD simulations, I managed to come with an acceptable set of results that have been further incorporated in the design process of the particular engine I worked on.

“FEIERABEND” During my time I had to quickly adapt to the work culture in German industry. Being at work means working, staying focused and being efficient. Coffee breaks were short and small talk was typically reserved for the lunch.

At the end of the day I was always surprised by the amount of work that I was able to complete during that day which was one thing that surely contributed to the final result of my thesis. On the other hand, free time is valued and the Germans even a special word for it: “Feierabend”. There is no direct translation in Dutch and English for this word, but it means something like the "free evening after work".

During Feierabend, I got involved with multiple things like barbecues with the other interns and thesis students, the Rolls-Royce after-work party and the Christmas party. And as focused as my colleagues and fellow interns were during work, as relaxed and chatty they became during those events. We had deep

discussions about the historical and societal differences between former East- and West Germany, which has certainly contributed to my understanding of the German language, history and culture. Before my thesis project I thought that the differences with the Netherlands would be minor, however, during my time at Rolls-Royce I got to know how important it is to understand our well-known neighbor and most important trade partner. Despite the fact that the country may be not as exotic as other far-away destinations, where you could do your internship or exchange program, I recommend anyone to spend some time abroad in Germany.

ICH BIN EIN BERLINER I found myself a nice room right in the heart of Kreuzberg, one of the vivid neighbourhoods of Berlin. I lived in a “Wohngemeinschaft” (WG) with four other German and French students. Within walking distance from my home, Tempelhofer feld was located, the field of the iconic former airport Tempelhof and now the largest public park in Berlin. Hence after work I found myself jogging on the 2km long runways where the Western allies organized the famous “luftbrücke” (Berlin airlift) when the Soviet Union blocked access to West-Berlin during the Cold War. Luckily enough, I arrived in Berlin in the right moment; just when all international students were undergoing their internships and Erasmus exchange programs.

This made it very easy to find new friends. At the beginning I was a bit overwhelmed by the endless possibilities for things to do in the city.

I wanted to see everything and experience everything so I typically spent the whole weekend outside, loosing track of time a little bit.

Berlin is a city where life outside never seems

to stop. The public transport runs all night, nightshops (“spätkauf”) on every corner of the street making it possible to buy drinks and food all day and all night, and the nightlife goes on forever, so no need to go home. As the weather was getting better at the beginning of the summer, cultural street events were organized around my neighborhood almost every weekend, like the Tage des Arbeits (labor’s day street festival), Karneval der Kulturen and later the “Weltmeisterschaft” (world cup football) which Germany won in the final, causing a big party. In November, Berlin celebrated the 25th anniversary of the fall of the wall. During the weekend numerous historical expositions were shown, reminding of the city’s turbulent past that gives the city its very distinct atmosphere. Whether it was dancing till the morning hours in one of the famous night clubs, swimming and relaxing at one of the lakes in the outskirts of the city, strolling in the Mauerpark to watch the street artists, or ending up at some open air festival somewhere around the shore of the Spree river, every weekend was like a new adventure. This gave me the energy to keep the focus during the week, during the moments of being stuck like every thesis student experiences, as well as the moments of necessary hard work to finish the project in time successfully.

Performing my thesis at Rolls-Royce proved to be a unique challenge for me where I touched a bit of every aspect of the process of applying CFD on complex industrial geometries.

This, together with the life I had in Berlin and all the wonderful people I met, made these 9 months to be an unforgettable experience.

One thing is for sure, I will keep coming back to this place!

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TIME FLIES

THE BELL BOEING V-22 OSPREY Victor Gutgesell, BSc Student Aerospace Engineering & Editor, Leonardo Times

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HDWALLPAPERS

Thirty years of tiltrotor technology: a look back For the last thirty years, the V-22 Osprey has been subject of a lot of controversies. Developed by Bell Helicopters and Boeing, wanted by the U.S. military, and almost cancelled by republican Secretary of Defense Dick Cheney, the V-22 went a long way to its current success.

“FIRST TO FIGHT” In early November 2013, major parts of Southeast Asia had been struck by typhoon Haiyan.

The Philippines were struck the hardest, causing a humanitarian crisis. In total, 39 countries sent aid to the Philippines after the catastrophe. Whilst it took most nations several days to arrive, the U.S. was there the next day. This time, the U.S. Marines were the first to aid and not the first to fight.

Their quick response was only possible thanks to the V-22 Osprey. Shortly after the typhoon, a formation of twelve V-22s was sent from Okinawa, Japan. It was accompanied by a MC-130 for mid-air refueling. In this manner, the V-22s were able to fly non-stop from Okinawa to the Philippines; something a regular helicopter could never do. Once in the Philippines, the V-22s used their helicopter mode to provide aid to the most remote places without proper runways, saving a lot of lives [1].

than usual. This development ultimately outdated the CH-46 Sea Knight, because the shores were suddenly out of range. With their claim to be “first to fight” the U.S. Marines were facing a new dilemma. Even though their ships were on site, they were unable to reach shore.

“A NEW TYPE AIRCRAFT” The situation was clear: The U.S. military was in the need of “A new type of aircraft, which could not only take off and land vertically but also could carry combat troops, and do so at speed”[3]. In this context the Department of Defense (DoD) created the Joint-service Vertical take-off/landing Experimental (JVX).

The JVX program was placed under the leadership of the U.S. Army, the greatest arm of U.S. defense. Navy, Army, Marines and Air Force began to work on a concept for such an aircraft, by defining its requirements. Soon after, the JVX program started to collect bids.

In the end, JVX received one bid only, even

“The most flexible, capable & revolutionary combat troop transport aircraft in the world.”

– U.S. Navy In 1980, the U.S. Marines wished for a V-22 type aircraft for a rescue mission of another kind. Iranian students had seized the U.S. embassy in Tehran [2], holding 52 diplomats hostage. When President Jimmy Carter failed to negotiate the release of the hostages, the Marines were assigned with a mission to rescue the diplomats. The key element of the mission was to use eight RH-53 helicopters to fly to the embassy and rescue the hostages.

The mission started going awry in its preparation stage. Three of the eight helicopters had to return to the USS Nimitz because of mechanical failures. After arriving at Desert One, a secret military base in Iran, a series of severe technical errors lead to the cancellation of the mission. The Marines were forced to leave the remaining five helicopters behind and abandon Desert One. The operation went down in history as the Desert One Debacle. Even though the Marines were the “first to fight”, it was a major drawback.

At the same time, the development in sea defense missiles forced the U.S. Marines to anchor their ships further away from the shore

though all major U.S. aviation companies had previously expressed their interest. In 1983, a joint venture of Boeing Helicopters and Bell Helicopters was chosen as the contracted partners of the JVX program. The proposed aircraft was to be the first prototype of a tiltrotor military airplane [4]. The DoD and the Navy were against the tiltrotor concept; eventually they got overruled by congress, which always remained on the side of the Marines.

The first six prototypes entered production in January 1985. For the first time, the aircraft was fully unveiled and given the name V-22 Osprey. The aircraft received a huge hype and expectations were high. In 1988, Terry Arnold, communications manager of Bell said “that plane right out there is probably going to be in the Smithsonian someday - that very airplane!” [5]. Many people saw a chance for a safer way of landing an aircraft on a carrier by using the tiltrotor technology. That same year, however, the project faced its first problems.

The Army decided to leave the program. With the army providing a large part of the funding for the program, this caused a period of uncer LEONARDO TIMES N°3 2015

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Mid-March 1989, V-22 prototypes 1 and 2 successfully completed their first flight tests in helicopter mode, followed by prototype 3 in airplane mode. However, as the costs increased, Dick Cheney made another attempt to stop the program in its tracks. Eventually, he was overruled by the Congress, which in return granted unrequested funding for the project. The V-22’s future seemed assured, until a disastrous flight test in 1991. When testing prototype 4, the pilots lost control shortly after lift off. The aircraft started tumbling and crashed right after. Miraculously, none of the pilots died in the accident [7]. In 1992, another flight test led to seven casualties. The program was temporarily stopped to conduct an investigation of both accidents. It was found that some of the electronics were falsely wired.

Following these accidents, a public controversy broke out. The V-22 became the subject of many debates and made it as far as the presidential elections in 1993. While Bush administration opted against the V-22, Clinton insisted on its continuation. Eventually Clinton won the elections and the program was safe again.

“A FLYING SHAME”

TIME

In 2000, after a redesigning campaign of the V-22, another 19 Marines died in a flight test.

Further investigations showed that this time the accidents did not happen due to technical, but human errors. The analysis of the flight had shown that shortly after the take-off, when changing into airplane mode, the V-22

TIME Magazine Cover Oct. 8, 2007.

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IR-PSRI.COM

tainty. Promptly after this drawback, the V-22 survived a vote in the Senate, which could have led to the termination of the program.

Nevertheless, the Pentagon advised the Navy to halt its spending for the V-22. With only the Marines and the Air Force left in the program, the V-22 continued. It had the support of Senate and Congress; however, the administration of the President at this time, George H.W. Bush, with Secretary of Defense being Dick Cheney, opted against it [6].

Marines supplying aid to Philippines with Ospreys. entered a deep-stall. This stall eventually led to the crash. The pilot had shifted the rotors too fast, against the engineers’ recommendations.

This called for a special training for V-22 pilots.

Regardless, fuel was added to the fire and the debate about the V-22 was raging once again. By that time its costs had surpassed ten times its initial budget of $2.5 billion. With costs so high, safety so low and equipped with only two machine guns, doubts about its suitability for combat zones rose up again. Furthermore, the casualties the testing phase had led to the aircraft being very unpopular amongst the American people and even within the Marines. People started calling it the “Widow Maker” [8]. In total, 39 people died while testing the V-22. In 2007, the Times Magazine published an article called “A Flying Shame”, marking the V-22 as failure. It seemed like the concept of a tiltrotor aircraft was finally proven to have failed.

On a political level, however, nothing happened. By then, too much time and effort and above all, too much money had been spent to now denounce it as a failure. Maybe that was for the better good; nowadays the Marines and the Air Force are using the V-22 on a daily basis. Even the Navy is looking at it again; who also fancies purchasing some. In the last few years, a number of successful rescue and transport missions were flown with the V-22. And from 2015 onwards, the U.S. Marine Corps wants to use the Osprey in combat zones like Afghanistan and Iraq. For this special purpose the V-22 will be modified to carry missiles, increasing its firepower.

After its success in the Philippines, other countries have expressed their interest in the V-22.

Israel, Korea, and Japan have started negotiating the terms for a purchase.

However, before a foreign nation will be equipped with the V-22, the President himself might get one. After 9/11, the Department of Defense concluded that the current fleet of Marine Ones needed major upgrade to meet today’s security standards. When in 2010 the U.S. Navy started asking companies to sug-

gest alternatives for the Sea King Helicopter.

Amongst the suggestions was Bell-Boeing’s V-22 Osprey. Meeting the criteria for an alternative Marine One, which have earlier been set out by the Marine Corps, the White House purchased several V-22s. As of now only the V-22s are allowed to accompany the President and transport lower state officials. The safety concerns from the V-22s past have still not been overcome. For one, the V-22 has no auto-rotation capability. Bell and Boeing claim it is safe enough, because of the connection between its two rotor shafts; with this technology one motor can power both propellers. Furthermore, the aircraft has the ability to glide, but with its very small wings, a safe crash landing is not a given in the eyes of the safety board.

The V-22 is probably one of the most controversial airplanes out there and, like a lot of revolutionary technologies, it came with a price tag. Let’s hope it was worth it.

References [1] stripes.com, “Marine Ospreys proving their worth in Philippines”, November 21, 2013 [2] mindef.gov.sg, “Operation Eagle Claw, 1980: A Case Study In Crisis Management and Military Planning”, Back Issues, Jounral V28 N2, 2002 [3] Mackenzie Richard, “Flight of the V-22 Osprey”, Mackenzie Productions for Military Channel, 7 April 2008, Retrieved: 29 March 2009 [4] Hybrid Craft Being Developed for Military and Civilian Use, David Kishiyama, Los Angeles Times, August 31, 1984 [5] Vertical-takeoff plane may be the 21st century’s intercity bus, Tom Belden, Toronto Star, May 23, 1988 [6] centerforsecuritypolicy.org, ‘New Democrat’ Watch #6: Will V-22’s Foes Be Able To Kill This Dual-Use Asset on Clinton’s Watch?, June 29, 1993 [7] globalsecurity.org, V-22 Osprey [8] V-22 OSPREY, Lee Gaillard, Center for Defense Information, 2006

Our mission one hundred percent www.airbusDS.nl

SPACE DEPARTMENT

25 YEARS 40

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ESA/NASA

THE CARINA NEBULA This image shows a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth and death - is taking place.

HUBBLE SPACE TELESCOPE Ruud Bokdam and Bram Koops, Students Aerospace Engineering, members of the 29th space department

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ESA/NASA

Dust Pillar of the Carina Nebula in the Infrared Spectrum

Dust Pillar of the Carina Nebula in the Visible Spectrum

ESA/NASA

Nearly 45 years ago, NASA and ESA began planning for a space telescope that could transcend the blurring effects of the atmosphere and take clearer images of the Universe than ever before. In 1990, the idea finally became a reality. Hubble has ever since exceeded all expectations.

EARLY TROUBLES Perhaps the most famous telescope in the world, it has been dealing with high expectations from the beginning. However, like any major project, it had also experienced serious problems and had been very close to complete failure several times. Before and after its launch into a low earth orbit, the telescope had to overcome severe problems that could have led to its cancellation.

Hubble would be able to see the universe in much more detail than any other telescope before due to its state of the art cameras on board. Designing and building this accurate and sensitive equipment is only half the story. Hubble Telescope has to remain focused with an accuracy of 0.007 arcsec. Furthermore, the mirror of Hubble would be the largest and smoothest ever made. If the Earth’s surface would be polished to the same accuracy as Hubble’s primary mirror, the largest deviation would be less than ten centimeters. This mirror was also the first one to be polished by computers instead of humans. The creation of the mirror took longer than anyone had anticipated and NASA was running short on time and money to finish this 42

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project. This resulted in NASA skipping the final verification steps of the mirror, despite the concerns of the engineers building it.

After six years, the mirror was completed and the engineers handed it over to NASA. Hubble would have been launched shortly after, had the Space Shuttle Challenger not exploded on launch. The launch was delayed by almost four years due to the ongoing investigation of the accident.

Finally, on April 24, 1990, Hubble was launched onboard the Space Shuttle Discovery and a day later deployed into space, at an altitude of around 600km.

As soon as the umbilical from the Space Shuttle was disconnected, it ran on internal power and the solar panels had to be deployed quickly. The first extended perfectly, but the second one stopped unrolling after about forty centimeters, due to a sensor measuring too much tension in the panel. Hubble was not receiving enough sunlight to survive very long and a solution had to be found and executed within hours. Finally, the faulty sensor was deactivated and the panel deployed fully.

Shortly after this, Hubble took its first images. However, the primary mirror had an

error of just 2.2 micrometers in its surface quality, which was enough to cause all images to be useless. This was the biggest problem yet for the Hubble Space Telescope and NASA. Fortunately, the data from the images helped scientists understand and pinpoint the exact problem.

Dozens of ideas were proposed to repair Hubble, from a giant lens over the entire front surface to astronauts manually crawling into the telescopes and reapplying the coating on the mirror.

In the end, a different solution was chosen.

The five scientific instruments were all assembled modularly in Hubble in such a way that they can easily be replaced.

The Wide Field Planetary Camera, which should make the most spectacular images of the universe, was already being upgraded into a newer version. A dedicated Shuttle mission would replace this camera with its successor, which had the exact opposite flaw of the primary mirror, thereby cancelling the error. For the remaining instruments, a set of lenses was created which would be placed in front of the instruments to correct the light coming for the main mirror. In December 1993, the first service mission in history was com-

ESA/NASA

NGC 602 IN THE FLYING LIZARD NEBULA Near the outskirts of the Small Magellanic Cloud, a satellite galaxy some 200 thousand light-years distant, lies 5 million year young star cluster NGC 602. Surrounded by natal gas and dust, NGC 602 is just below center in this telescopic field of view with the angular size of the Full Moon on the sky. The cluster itself is about 200 lightyears in diameter. Glowing interior ridges and swept back shapes strongly suggest that energetic radiation and shock waves from NGC 602’s massive young stars have eroded the dusty material and triggered a progression of star formation moving away from the cluster’s center.

pleted successful.

Hubble exhibited its true capabilities when, in the Christmas holiday of 1995, it pointed its camera’s at the tiny piece of sky thought to be empty, for ten consecutive days. It turned out this small black patch in the sky contained thousands of galaxies with billions of stars each. Three more service missions would follow, with the last one launched in 2009 after being postponed due to the Space Shuttle Colombia disaster.

DISCOVERIES OF HUBBLE Despite an early problem, since the launch back in 1990, the Hubble space telescope has made many fascinating discoveries that have revolutionized our understanding of the universe. Some of Hubble's most spectacular and intriguing accomplishments are discussed here:

1. AGE OF THE UNIVERSE. For a long time scientists have tried to find out, how old the universe actually is. Before Hubble, this was fairly uncertain and lead to impossible conclusions and paradoxes. A star, for instances, could have been found to be older than the universe itself. Hubble

helped in estimating the universe’s age to be around 13.75 billion years. This estimation was more precise than any earlier. The question about the age of the universe is fundamental to many problems in physics.

Finally, physicists had a date to model the theory of the big bang and they were able to validate Edwin Hubble’s (the namesake of the telescope) model of an expanding universe. In further studies, it was even found that the universe was expanding at an accelerating rate. Also, seemingly unrelated fields of physics benefit from this cosmic parameter, for instance the calculations regarding the determination of the mass of a neutrino

2. MASSIVE BLACK HOLES AT THE CENTER OF THE GALAXY. Hubble telescope discovered that super-massive black holes probably lurk in every galaxy that has a bulge of stars at its center. The mass of the black hole is proportional to the mass of the host galaxy, so that a galaxy twice as massive as another would have a black hole that is twice as massive. This discovery suggests that the growth of the black hole is linked to the formation of the galaxy in which it is located.

3. EXTRASOLAR ORGANIC MATTER. Besides observing large events, like supernovae and the birth of stars, the Hubble telescope is capable of observing much smaller events. For example, in 2007 Hubble made the very first detection of an organic molecule in the atmosphere of a Jupiter-sized planet orbiting another star.

This amazing breakthrough is an important step towards eventually identifying signs of life on other planets outside our solar system. In order to detect organic molecules on planets around other stars, spectroscopies are made. This method splits light into its component frequencies to reveal the "fingerprints" of various chemicals, as every element on the periodic table absorbs an emits a different set of frequencies

4. PROTOPLANETARY DISCS. How do planets come into existence? This question seems oddly simple, looking at the other questions Hubble had already answered. Nonetheless, the process of planetary formation had been a mystery for a long time. The disc of dust and gas surrounding a newborn star becomes flatter and denser, allowing matter in the disc to clump together into planetary building LEONARDO TIMES N°3 2015

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ESA/NASA

WESTERLUND 2 This picture released for the 25th anniversary of the telescope shows a giant cluster of about 3,000 stars called Westerlund 2, named for Swedish astronomer Bengt Westerlund, who discovered the grouping in the 1960s. The giant star cluster is only about 2 million years old and contains some of our galaxy’s hottest, brightest, and most massive stars. Some of its heftiest stars unleash torrents of ultraviolet light and hurricane-force winds of charged particles that etch at the enveloping hydrogen gas cloud.

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blocks. This observation supports the theories behind planet formation, which are necessary for understanding our origin.

Being still operational after 25 years, the spacecraft exceeds its initial expectations.

As a machine, it is constructed well enough to surpass this time, and as a telescope, it is so precise, that its data is still relevant. Five missions to service it over the years not only provided vital repairs, but also provided it with upgrades that gave it new capabilities each time. The result is that Hubble is capable of making new discoveries and captures even more breath-taking images like the one of the Carina Nebula.

THE JAMES WEBB TELESCOPE Although Hubble has surprised everyone with its current lifetime, it will not remain in service forever. No one at this point knows how long it will be operational but its successor is currently already being built; the James Webb Space Telescope (JWST). Like Hubble, this stateof-the-art space telescope will have to live up to high expectations and is said to be the replacement for Hubble. However, there are a few important differences between Hubble and the James Web Space Telescope.

Firstly, Hubble looks at galaxies and stars in the visible and near visible wavelengths. The JWST will only look at the infrared wavelengths of the spectrum. Only in this way will it be possible to look at the oldest galaxies in existence, whose light is 13.5 million years old.

These galaxies move away from Earth at extremely high velocities, causing their normal visible light to change to infrared in a process known as red shifting. Due to the radiation, which is emitted by every warm body, and in order to avoid distortion of the measurements caused by its own heat, the telescope must be cooled down to 50K (-233°C). A massive sun shield will be installed, which blocks any radiation from the sun and helps it to stay cold, as can be seen in Figure 1. Some of the scientific instruments even require helium to cool them down to 7K. The second main difference between the two telescopes is their orbits. Hubble is orbiting the Earth at an altitude of approximately 550km above the surface, making it relatively easily accessible for maintenance and updates. The James Webb Telescope, however, will be located at the second Lagrange point (L2), 1.5 million km above the Earth’s surface. Normally such a large orbit would take more than one year to complete, but as the gravitational forces of the Sun and Earth at that location point in the same direction, it will complete its orbit in exactly one year. This distance does mean that the JWST is not serviceable like Hubble. It has to complete its mission correctly the first time; there can be no flaws in the system.

With its 13.2m in length and a primary mirror stretching 2.4m in diameter, Hubble is large.

JWST is enormous. It has a multiple layer sunshield measuring over twenty by fourteen

Figure 1 - Important parts of the James Webb telescope, including the sunshield.

Figure 2 - The primary mirrors of the Hubble space telescope (left) and the James Webb space telescope (right). meters, and a primary mirror more than five times the size of Hubble. (Figure 2) To put this into perspective, Hubble is about the size of a school bus whereas the JWST stretches across an entire tennis court. This size does create an issue with the delivery into space.

There is currently no launch vehicle, nor there will be in the near future, that is even remotely large enough to bring the JWST to its orbit in one piece. However, the engineers have come up with a clever solution; they will fold it up. It will be launched in 2018 on the Ariane V rocket, while being folded up, so it can fit into the cargo bay, only a quarter of the size of the fully deployed telescope. After its deployment in space, it will completely unfold, including the sunshields, solar arrays, mirrors and antennas. It has to be done automatically and with extreme precision to ensure everything lines up correctly so the JWST can continue to improve our understanding of the universe.

References [1]http://www.nasa.gov/mission_pages/ hubble/story/index.html[2] http://www.space. com/17-amazing-hubble-discoveries.html [2]http://www.space.com/17-amazing-hubble-discoveries.html The Space Department The Space Department promotes astronautics among the students and employees of the faculty of Aerospace Engineering at Delft University Technology by organizing lectures and excursions.

LEONARDO TIMES N°3 2015

45

ESA/NASA

TADPOLE’S TIDAL TAIL This images shows a disrupted galaxy, Arp 188, nicknamed the Tadpole galaxy.

The cosmic tadpole is a mere 420 million light-years distant toward the northern constellation Draco. Its eye-catching tail is about 280 thousand light-years long and features massive, bright blue star clusters.

Scientists believe that a more compact intruder galaxy crossed in front of Arp 188 from left to right in this view - and was slung around behind the Tadpole via gravitational attraction. During the close encounter, tidal forces drew out the galaxy’s stars, gas, and dust forming the spectacular tail. The intruder galaxy itself, estimated to lie about 300 thousand light-years behind the Tadpole, can be seen through foreground spiral arms at the upper left. Like its terrestrial namesake, the Tadpole Galaxy will likely lose it tail as it grows older, the tail’s star clusters forming smaller satellites of the large spiral galaxy.

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N°3 2015 LEONARDO TIMES

ESA/NASA

THE TARANTULA NEBULA IN THE LARGE MAGELLANIC CLOUD It is the largest and most complex star forming region in the entire galactic neighborhood. Located in the Large Magellanic Cloud, a small satellite galaxy orbiting our Milky Way galaxy, the region’s spidery appearance is responsible for its popular name, the Tarantula nebula. This tarantula, however, is about 1,000 light-years across.

Were it placed at the distance of Milky Way’s Orion Nebula, only 1,500 light-years distant and the nearest stellar nursery to Earth, it would appear to cover about 30 degrees (60 full moons) on the sky. Intriguing details of the nebula are visible in the above image shown in near true colors.

The spindly arms of the Tarantula nebula surround NGC 2070, a star cluster that contains some of the brightest, most massive stars known, visible in blue in the image center. Since massive stars live fast and die young, it is not so surprising that the cosmic Tarantula also lies near the site of a close recent supernova.

LEONARDO TIMES N°3 2015

47

SAF

SAF

FPP

HOW TO TRAIN A PILOT

The way into the cockpit of the Swiss Air Force Lt. Sebastian Blanke, Military Pilot Aspirant, Swiss Air Force To be able to fly a military aircraft, aspirants have to go through a tough selection process. Eventually only a fraction of the applicants will be able to call themselves pilots. One of these people is Sebastian Blanke, Lieutenant of the Swiss Army, currently an aspirant to becoming a pilot. He shares his experiences exclusively with Leonardo Times.

A

s a child, many people have the dream of becoming a pilot. I wasn’t any different. Huge, complex, and fast technical systems like airplanes always fascinated me.

As I grew older, the dream grew with me. Finally, at the age of seventeen, I decided to pursue my dream and try to become a pilot of the Swiss Air Force (SAF).

The very first step on the journey to the cockpit is SPHAIR. It is the platform of the SAF, which offers every Swiss citizen between the ages of 17 and 21 an opportunity to start a career in aviation, irrespective of their financial or cultural background. Not only the SAF, but also many civil aviation companies support and fund this platform. Enrolment consists of two steps.

The first step is a one-day screening where mathematical skills, memory tasks and three-dimensional imagination as well as 48

N°3 2015 LEONARDO TIMES

various other aspects are being tested. The second step of the SPHAIR-program is a twoweek practical flight course, where one can display his talents in flying a single-engine piston aircraft in the shortest possible time.

This was my first hands-on contact with aviation. The pace of the course was very high and demanding; yet, after a few flights, I was able to take-off, fly and land a small aircraft all by myself.

Having passed the SPHAIR selection successfully, I applied as pilot candidate for the Swiss military, which is what around 100 young Swiss citizens do every year. Another two steps of the military pilot selection were carried out in the aeromedical center of the SAF and lasted three days. The first day, I had several long interviews with psychologists trying to learn everything about me and find out if I was fit for the job. Funny enough, I had the im-

pression that they knew me better than I knew myself afterwards.

The next stage consisted of group tests; assessing my social abilities. Finally a complete medical check- up was carried out. The second last hurdle that separated me from my dream job was an intense five-day testing phase in a simulator where my performance and coordination abilities under stress were assessed.

In order to have a military basic formation, every future pilot has to undergo an officer education, just like every other officer in the Swiss Army. We were not only taught tactical and strategic thinking, but also took responsibility for men and material. I served as an ammunition officer at the ground troops of the SAF. When my pilot class met for the first time after the ground training, it turned out to be a mix from all different divisions of the Swiss Army.

Having finished my fourteen-month officer education carrying the rank of a lieutenant, I and fourteen others were admitted for the long awaited last stage of the selection on the air base of Locarno in southern Switzerland.

Flying the 550 horsepower, turbine driven PC-7 with a meagre background of only nine hours of experience on a Piper Warrior was simply overwhelming. The training started with basic flight maneuvers and was quickly extended with some aerobatics. Although this was the first contact with aerobatics for most of us, our stomachs handled the turns, rolls, looping’s and the G-forces of up to four G’s pretty well. Sadly, I was one of those whose stomach needed a bit more time to get used to this new sensation. Beside aerobatics, the flight program consisted of maneuvers like idle/zero flaps approaches, narrow turns, and navigation flights with high precision work and tricky extra tasks. After the five check flights with the examiner not saying or doing anything it was announced that eleven of us had been chosen to be trained as military pilots. From this moment on, I was proudly employed as part of pilot class 13 for the pilot school of the SAF.

Currently, I am studying aviation engineering at the Zürich University of Applied Sciences (ZHAW) as part of my flying education. Here, all of us cadet air force pilots are studying “incognito” in civilian clothes alongside all the other engineering students, which creates many private contacts between future engineers, airline pilots, air traffic controllers, or aviation safety experts. This university offers the possibility of combining a Bachelor degree with a commercial pilot license (CPL/ IR/ MCC), something unique in Switzerland. This degree course not only gives you all the important basic technical tools you need as engineer, it also covers a wide array of other topics. Subjects from aviation law over human factors to business process engineering are very helpful to keep the overview in the cross-linked field of aviation. The decision about who is going to become a helicopter pilot and who is going to become a fighter pilot is also taken during this period. It is based on the current needs of the air force but personal preferences will be respected, whenever possible. Once I have finished my studies and obtained the CPL in about three years, I will change from the civil part of the flying formation to the military one.

The military flying formation will then be a two-year training course on the Eurocopter EC-635/ 135 for the helicopter pilots or on PC-7 and PC-21 for the future jet pilots. As part of the flight training comes a very important

SAF

SAF

Within four weeks and thirteen flights, we were first trained how to fly the Pilatus PC-7 and then examined in five more check flights. During the first week, we learned a lot about the aircraft, the geography of southern Switzerland, basic flight maneuvers and of course the whole checklist. Studying was so intense; we literally recited the checklist in our sleep. After this theoretical week on ground, we were all eagerly waiting to take off with this beautiful bird for the first time.

and intense phase of survival training. I was taught how to survive in different conditions on the ground i.e. after a crash or after being shot down and how to survive in my inflatable life raft after a landing on water. On graduation as a military pilot one will get his “wings” and will be integrated in the squadrons, training on the Eurocopter AS 532 “Super Puma”, or on the Boeing F/A 18 C/ D “Hornet”. As a military pilot with the SAF, your daily work consists of air defense and air policing training missions for jet pilots and of air transports, search and rescue (SAR), or firefighting missions for helicopter pilots.

As you know by now, with this rather demanding job profile, one has to pass many hurdles and overcome many challenges to finally sit in a cockpit of a SAF aircraft. The rewards however, are worth it all: The cockpit and plane become an extension of you. It’s probably the closest you can be to being part machine.

The plane is your body but you are the brain.

You will discover your personal limits and, with the support of your fellow colleagues, push them even further. As anyone who has flown himself knows, flying is more than a job; it is passion, freedom and desire. For me, it is the best job in the world.

References [1] www.Airforcepilot.ch [2] www.sphair.ch [3] www.qnh1013.ch (German Only) LEONARDO TIMES N°3 2015

49

SWISS SPACE CENTER

SPACE

IN PURSUIT OF SPACE DEBRIS

The CleanSpace One mission

Marco Gómez Jenkins, MSc Graduate Aerospace Engineering, Faculty of Aerospace Engineering, TU Delft Space debris is slowly becoming a growing threat to current manned and unmanned spacecraft. CleanSpace One is an innovative mission which aims to demonstrate technology related to orbital debris removal by de-orbiting Cube a piece of orbital debris. It is one of the first endeavors in the cleaning of space.

THE PROBLEM OF SPACE DEBRIS

SWISS SPACE CENTER

Imagine being part of a team working on a mission for an emerging space nation. This is the country’s first effort in space, so they have placed a substantial investment in the project in order to assure its success. After considerable time and effort spent designing, constructing and testing the spacecraft for the harsh environment it will be placed in, it is finally launched and placed in the correct orbit.

Commands are sent from the ground station to the satellite and it responds, stating that it is in good health. The mission proceeds by

turning on instruments and starting the collection of data. It seems to be a success, until the team receives a warning that the spacecraft is in a possible collision course with a cloud of space debris. After hours of tension, the team receives the worst possible news: the collision occurred and no further communication is possible with the satellite. A year-long mission is shortened to less than three weeks due to a cloud of space debris.

The hypothetical scenario described is what the nation of Ecuador experienced with its Pegaso mission. It was their first endeavor launched into space, aiming to demonstrate technology related to nanosatellites. The spacecraft was injected into orbit on May 5th, 2013 and experienced a terminal collision with a debris cloud from a Tsyklon-3 rocket stage on May 23rd of the same year (Nader, 2014). Although this may seem like an isolated event, the threat of space debris has become very real over the last years for manned and unmanned spacecraft. The quantity in orbit will continue to rise at a rapid pace, with experts predicting that it will triple by 2030.

THE SOLUTION: CLEANSPACE ONE Figure 1 - Dimensions of the CSO spacecraft.

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N°3 2015 LEONARDO TIMES

Many of the major space agencies are studying concept that will aid in the removal of de-

bris in space. The greatest problem lies in the formation flying and capture of a target in orbit.

Although rendezvousing and docking with a spacecraft in orbit is considered routine by now, there has never been a capture of an uncooperative object or satellite in space. This is the main purpose of the CleanSpace One (CSO) mission, managed by the Swiss Space Center of the École Polytechnique Fédérale de Lausanne (EPFL). It aims at demonstrating technology related to the rendezvous, capture and de-orbit of a piece of space debris.

Just like the European Space Agency used SMART-1 to test electric propulsion technology, the Swiss Space Center will use CSO to test debris removal technology and apply it to future spacecraft.

The microsatellite used for this mission has a mass of 35 kg and a volume of 30 cm x 30 cm x 34 cm, as displayed in Figure 1. It will use a small electric propulsion system to rendezvous and de-orbit a piece of orbital debris and a small robotic arm to capture it. For this mission the target debris is SwissCube, a Cubesat launched in 2009 and formerly operated by the Swiss Space Center. Its mission was to study the nightglow within the Earth’s atmosphere, which it successfully did for more than 60 months. This CubeSat is in a Sun-synchronous orbit with an approximate altitude of 700 km and an inclination of 98°. It was officially retired on December 2nd, 2011, making it a piece of space debris. In this mission, CSO and SwissCube are also referred to as the

SWISS SPACE CENTER

position its thruster along the center of gravity (CG) of the target-chaser system and use the electric propulsion system to lower the altitude of the system from 700 to 200 km.

From this point on, the propulsion system will be turned off and the orbit of the two spacecraft will gradually decrease in altitude due to atmospheric effects until re-entry occurs. The mission is completed when the target-chaser system burns up in the atmosphere. A controlled re-entry will not be used since the system poses no threat of landing on Earth.

STEP BY STEP, PIECE BY PIECE…

Figure 2 - Concept of operations for the CSO mission.

CONCEPT OF OPERATIONS The concept of operations provides a more detailed description of the different stages of the mission. For CSO, it is divided into four phases, which are the far-range operations, approach, capture and de-orbit, as presented in Figure 2. The different phases are explained in more detail in the following subsections.

FAR-RANGE OPERATIONS The far-range operations phase starts out with the launch of CSO. The first maneuver that the chaser spacecraft must perform is transferring from its initial orbit to the orbit of the target. It will be injected in the former using the SOAR suborbital space plane provided by Swiss Space Systems (S3). At the end of the far-range operations, the chaser will be at a distance of approximately 30-50 km of the target. This is defined as the first hold point. Hold points are commonly used in rendezvous since they provide extra time to check on the operations without the chaser having to significantly change its position relative to the target (Wakker, 2011).

APPROACH

As the old idiom states ‘Rome wasn’t built in a day’. It is certain that space can’t be cleaned in a day. It will require great efforts to solve this ever-growing problem and CSO will be leading the way.

For more information, please contact the author at: marco.gom.jen@gmail.com

CAPTURE The chaser will be along the target’s main rotational axis in order to provide a safer capture.

There are three possible capture mechanisms for the CSO mission: a rigid link, such as a standard robotic arm, a flexible link, such as a net or harpoon, or a contactless system, such as shooting foam or ions at the target. The most likely candidate for now is a rigid link that consists of a deployable arm, wrist joint and grappler. This will result in a more complex capture than the other two options but rigid links are more developed and have flight heritage.

DE-ORBIT

References [1] R. Nader, H. Carrion and M. Uriguen. “The Ecuadorian Experience in Space: The NEE Satellite Constellation”, 65th International Astronautical Congress, Toronto, Canada, 2014.

[2] M. Richard, L. Kronig, F. Belloni, S. Rossi, V. Gass, C. Paccolar, J.P. Thiran, S. Araomi, I. Gavrilovich and H. Shea. “Uncooperative rendezvous and docking for microsats”, 6th international conference on recent advances in space technologies, Istanbul, Turkey, 2013.

[3] K. Wakker. AE4874: Astrodynamics II Lecture Notes, Delft University of Technology, July, 2011.

Once the target has been captured, CSO will ECUADORIAN CIVILIAN SPACE AGENCY

Phasing with SwissCube starts from the first hold point. The chaser will go from a distance of 30-50 km to 5-10 km from the target. The latter distance is the second hold point and

this is where target detection will take place.

Once SwissCube is found and locked upon by the chaser, it will start closing in by moving even closer to a distance of approximately 300 m, also known as the third hold point. After this, the chaser will make the final approach that ends when it is 10-20 m away from the target. When it reaches the fourth hold point, it will start proximity operations, which consist of characterizing the motion of SwissCube by flying around it. A grappling point will be selected after characterization of the dynamics has taken place. Once this occurs the grappling mechanism will be deployed and CSO will approach the target until it is at a distance of 1-2 m.

SWISS SPACE CENTER

chaser and target, respectively.

Although CSO is one of the first efforts to cleanup space debris, some may argue that it will be an ineffective mission due to the fact that it will only eliminate one piece of space debris that is rather small. This seems like quite a Sisyphean task, considering that there are hundreds of thousands of space debris in orbit. However, the success of this mission will help demonstrate the technology’s potential.

In the future the larger spacecraft might be equipped with CSO’s technology; enabling them to remove multiple pieces of space debris at once.

Pegaso spacecraft in the clean room with engineers.

Artist rendition of SwissCube in orbit.

LEONARDO TIMES N°3 2015

51

ROLLS-ROYCE DEUTSCHLAND

ASM

SELF-HEALING OF CREEP DAMAGED STEEL

Studying self-healing of ultra-fine cracks by Nano scale precipitation

Maarten Gramsma, MSc Graduate, ASM chair, Faculty of Aerospace Engineering, TU Delft Creep is often seen as an undesired effect in metals, which may be a limiting factor in the lifetime of steel components. It may lead to premature fracture below the yield strength when exposed to elevated temperatures for long times, in combination with constant high stress. Self-healing is a promising approach to increase the lifetime performance of iron-based alloys and steels, which could drastically reduce maintenance and material costs for aerospace propulsion systems.

I

mproving the lifetime of critical air- and spacecraft components in high temperature environments is an essential aspect when it comes to making future airplanes more sustainable. Conventionally, making the material as strong as possible, preventing damage to evolve in the material, increases the lifetime of materials. With the idea of self-healing, damage at small scale is actually allowed in the material. Although these materials are less strong, they are capable to heal themselves to increase the lifetime. One may better speak then about damage management, rather than damage prevention. (Garcia, 2010) Here we can learn from nature, because it is already proven from evolution that it works very well in biological systems.

Creep, the time dependent elongation of a material under a constant applied stress, is an undesired effect that may be a limiting factor in 52

N°3 2015 LEONARDO TIMES

the lifetime of steel components used at high temperatures, and can lead to premature fracture below the static yield strength. (Callister, 2006) Therefore, self-healing of creep damage in steel alloys can be a promising way to make e.g. aircraft engines more durable.

Among the actual existing engineering materials, achieving self-healing in metals is still challenging. This has to do with the fact that the mobility of the solute atoms in the iron is only sufficient when the temperature is close to the melting point. (Van der Zwaag, 2011) This thesis research is only a small part of a larger research project on self-healing creep steels, which is conducted by Shasha Zhang and supervised by Dr. Niels van Dijk at the department of Fundamental Aspects of Materials and Energy (Reactor Institute Delft).

This project is also part of the IOP Self-healing Materials Program chaired by Prof. Sybrand

van der Zwaag, and is funded by the Dutch government.

DAMAGE FORMATION & MECHANISM OF SELF-HEALING When plastically deforming a metal, e.g. by creep, defects will be nucleated in the material. When these grow, they can combine and may form ultra-fine nano- and microcracks.

Consequently, this may lead to failure of the material. It is hence preferred to immobilize the growth of cracks already at the nano-stage.

A possible way to achieve this is to add mobile solute elements such as gold and molybdenum to the iron. When a static load is applied and nano-cracks are starting to develop, the solute elements will become available to diffuse towards these damage sites. These solutes will then come out of the solution in the matrix, and will form Au or Fe2Mo precipitates to fill these nano-scale cavities or cracks (Van der Zwaag, 2011), see Figure 1. In this situation creep damage is immobilized by site-selective precipitation, so that this damage remains static at its position. Hence, no ‘magic’ or nanobots are involved here. Therefore, it is crucial to gain understanding about the correlation between the defect evolution and the

N.H. VAN DIJK

Figure 1 - Schematic overview of the damage and self-healing mechanisms. precipitation behavior at high temperatures, in order to fully utilize the precipitation-induced self-healing mechanism in iron-based alloys.

The main part of this study was focused on Fe-Au and Fe-Au-B-N alloy samples, a type of steel that is being investigated since a couple of years and initiated at the time by Van der Zwaag and Van Dijk after intensive studies of Fe-Cu type alloys. The addition of copper to the iron has given some promising results, although the formation of Cu precipitates was not found to be occurring in a site-selective manner only at the damage sites, but more homogeneously through the material. Therefore, the idea to study iron with the copper atoms replaced by gold or molybdenum elements as a healing agent came into mind.

energy barrier for nucleation of precipitates in the iron-matrix. Gold or molybdenum therefore tend to segregate out of the bulk material towards the surface when it is dissolved in the iron-matrix. If this is the case, it should also have a preference to segregate towards nanoscale voids. This makes Fe-Au an excellent system to achieve selective Au segregation at defect sites, which is an important requirement for self-healing of defects. (Zhang, 2013) Whereas for gold some of the self-healing capabilities are already proven in previous researches, molybdenum is very recently selected to explore its self-healing potential in Fe-Mo alloys.

EXPERIMENTAL SET-UP By means of positron annihilation techniques used at the radiation facilities at the RID, the evolution of the defects inside the material and the healing of these are studied. Material samples of Fe-Mo and Fe-Au with and without boron and nitrogen atoms have been manu-

The reason why gold and molybdenum are selected has to do with their larger atomic sizes compared with the ‘host’ iron matrix atoms. This large atomic size difference results in a high strain energy, and therefore in a high 1,3 Ann. Au

FeAu

1,2

After deformation After healing/ageing Reference materials

Normalized W

1,1 1,0

Ann. Fe

Defect Au

1 AQ

2

0,9

4,5

3

Deformed 8%

6

Deformed 24%

0,8

Fractured FeAu

Defect Fe

0,7 0,99

8

7

1,00

1,01

1,02

1,03

1,04

1,05

1,06

1,07

1,08

Normalized S Figure 2 - Positron data showing the S versus W parameters for the Fe-Au alloy. AQ: As Quenched.

factured, on which several (cyclic) experiments are performed.

The cyclic measurements on Fe-Au and FeAu-B-N formed the main part of the experiments. After performing a solution heat treatment at 868°C for five hours, the samples are quenched to room temperature to obtain a super-saturated solid solution where all gold (and boron, nitrogen) atoms will be dissolved and trapped in the iron-matrix. Subsequently, a positron measurement with Coincidence Doppler Broadening (CDB) is conducted to measure the initial state of the material. After this, a small plastic deformation is introduced in the material by doing a tensile test, followed by an ageing treatment at 550°C for ten minutes (i.e. the healing step). Two positron measurements are done here: (1) after the deformation step and (2) after the healing step.

These deformation-ageing steps with positron measurements are then repeated for a certain number of cycles. A so-called S,W-plot is then obtained from the results. Furthermore, Vickers hardness and creep tests have been carried out in combination with Scanning Electron Microscopy (SEM), and also diffusion-based finite-element model calculations are performed to study the time it takes to fill a cavity. This may give additional (theoretical) insight in the diffusion processes of the solute elements towards the nano-scale defects.

FE-AU AND FE-AU-B-N CYCLIC MEASUREMENTS The cyclic experiments with repeated deformation-ageing cycles with CDB measurements that have been conducted with FeAu(B-N) alloy specimens, have resulted in an S,W-plot such as can be seen in figure 2. This figure shows the S versus W parameters for the Fe-Au alloy, normalized to the values of annealed iron, and is obtained from positron annihilation spectra. The blue line indicates roughly the trend for the range of the data points. This plot works as follows: when LEONARDO TIMES N°3 2015

53

a material is in a deformed state, the S and W should shift in the direction of the defect. After performing a successful healing step, the point should shift to the direction of Au. The S, W points for annealed iron, gold, and the defect (which is represented by the fractured Fe-Au) are shown as reference points.

It is observed here that all data points lie between the reference points, which should be the case. In most cases, after the deformation step the S,W point moves indeed towards the defect point. Also, after a healing step the expected shift towards Au is seen to occur in most of the cases. Therefore, it can be derived from this that the introduced defects are mostly healed during ageing. In some of the cycles in figure 2, this is indicated with a dashed line towards the Au reference point. Furthermore, from CDB measurements performed on FeAu-B-N alloy specimens and other cyclic tests performed without positron measurements, as well as creep tests and microscopic studies, it was seen that the presence of boron and nitrogen in the Fe-Au alloy retards the gold precipitation kinetics. This is also consistent with recent results. (Zhang et al., 2013)

FINITE ELEMENTS MODEL CALCULATIONS For a Fe-Mo alloy, finite element computations were carried out using a diffusion model based on continuum mechanics using the SEPRAN package. Here, creep cavity-filling times for various volume and grain-boundary diffusivities have been computed, as seen in figure 3. Moreover, so-called time exponents for creep cavity filling are derived from these computations. It follows that the filling of a creep cavity on a grain boundary can be well compared with the growth model of a precipitate on a grain boundary, which is already extensively studied by other researchers in the past.

(III) (II)

(I)

Figure 3 - Creep cavity filling times for various volume and grain-boundary diffusivities.

FE-MO HARDNESS RESULTS For Fe-Mo, Vickers Hardness tests have revealed two distinct stages in the precipitation process: a constant hardness stage and a stage where the hardness is reduced significantly (see figure 4). This could be explained by segregation towards precipitates at (sub) grain boundaries (or dislocation clusters), so that the bulk inside the grains becomes solute depleted. Hence, it could be derived from this that the solutes are selectively moving to the damaged sites. Also, from CDB measurements and SEM observations, it has been found that induced dislocations and other open-volume defects enhance the segregation and precipitation of Mo and Fe2Mo. Hence, there should be a tendency for site-selective precipitation at these defect sites.

This would make molybdenum a promising

200

Fe-Mo undeformed Fe-Mo 8% deformed

190

References

Hv0.5

170 160 150 140 130

AQ 0,1

1

10

100

1000

Ageing time (Hours) Figure 4 - Vickers hardness results for undeformed and deformed Fe-Mo alloy. AQ: As Quenched.

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CONCLUSION Overall based on the results in this research project, especially the Fe-Au system shows a high potential for achieving self-healing behavior of deformation-induced defects. Molybdenum could become a proper alternative to gold, although more research is required for this alloy element to gain more insight in the material processes. Finally, self-healing of deformation induced defects could be seen as a promising approach to extend the lifetime of iron-based alloys for structural applications at elevated temperatures. If you have further ideas or want to contribute to this research as a graduate student, you may contact the author for further information.

Contact info: Maarten Gramsma, m.e.gramsma@gmail.com

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self-healing agent for deformation-induced defects next to copper and gold, however further investigation is required to make it a proper alternative for application in iron-based structural alloys.

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[1] Garcia, S.J. and Dingemans, T., “Self-Healing Materials”, Lecture slides, Delft, 2010.

[2] Callister, W. D. J., “Material science and engineering, an introduction.”, 7th revise. New York: John Wiley & Sons, 2006.

[3] Van der Zwaag, S., “Self Healing materials - concept and applications”, 2nd edition, Ministry of Economic Affairs, Agriculture and Innovation, NL Agency - NL Innovation: IOP Self Healing Materials, 2011.

[4] Zhang, S., Kohlbrecher, J., Tichelaar, F.D., Langelaan, G., Brück, E., Van Der Zwaag, S., and Van Dijk, N.H., “Defect-induced Au precipitation in Fe-Au and Fe-Au-B-N alloys studied by in situ small-angle neutron scattering”, Acta Mater., vol. 61, no. 18, pp.

7009–7019, 2013.

www.thalesgroup.com/nl

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from another technical company, but the good atmosphere at Thales

looking for a technical company with an interesting product where

was decisive for me. People here are very helpful and take the time to

I could make use of my physics background. At the Beta Business

explain something. Thales certainly lives up to the image I had of it:

Fair [BètaBedrijvenBeurs] in Nijmegen I had a conversation with a

a high-tech company with a pleasant working environment.”

recruiter from Thales. She invited me to their head office to discuss the opportunities at Thales. One of the vacancies stood out right away, namely the position of Trial Conductor. I applied for this position and after a few interviews they hired me. Meanwhile, I have been working at Thales for a few months and am enjoying it very much. As the Trial Conductor I constantly build on the knowledge gained during my studies. I will regularly go abroad as part of a team to test our naval radar systems. At sea we show the client that our system is indeed as good as promised in the contract. We do this through various scenarios. For example, we have an F-16 fly in to see when the radar detects it first. While I was applying for jobs I also received an offer

“As the Trial Conductor I constantly build on the knowledge gained during my studies. I will regularly go abroad as part of a team to test our naval radar systems.”

Annelot Schuring Graduated in Physics, Radboud University Nijmegen, aged 24

Looking for a job, internship or graduation assignment?

Start your career at Thales! www.thalesgroup.com/nl

AELS

AELS

INTERVIEW

AIRCRAFT END-OF-LIFE SOLUTIONS

AELS

While Dirk-Jan van Heerden was doing his Masters in Aerospace Engineering’s degree at TU Delft he was inspired by an often overlooked aspect of an aircraft’s lifetime: “What happens with airplanes when they reach the end of their service life?”. From an academic point of view, this question was rarely asked. He started working on the subject, and after an internship at Boeing, he got the opportunity to do his thesis work on this topic at KLM Engineering and Maintenance. A solution had to be found for a stranded Boeing 747 at Schiphol Airport, and while

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the idea was that he would develop a solution for this specific aircraft, he eventually even got to manage the project, being in-charge of the 747’s disassembly.

Using the experience from this project, he created a business plan for dealing with End-Of-Life (EOL) solutions for aircraft, and proposed it to KLM as a possible new service. KLM insisted that their goal is to keep the aircraft flying, not the opposite.

This motivated Dirk-Jan to try it himself instead, and as a fresh Aerospace graduate, he started his own company called ‘Aeroscrap’. Later, he changed the name to Aircraft End-of-Life Solutions (AELS). The company is now almost celebrating its tenth anniversary, and Leonardo Times talked to him about how the company is doing today, and their plans for the future.

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Derk-Jan van Heerden sitting comfortably in seats from a disassembled aircraft just next to his office .

“What is your background and how exactly did you decide to study aerospace engineering?”

“In school, I really liked the technical courses, Physics, Mathematics and Chemistry. I was pretty good at them. For me, it was pretty obvious to go for a technical study. What I learnt about myself in the course of studies was that maybe I wasn’t the typical engineer. I am just not a person that can sit behind a computer to analyze, program, and calculate. It’s just not my thing! I am more of a people’s guy. I like interaction with people and I like the processes. So I figured, I was good at solving more interesting problems in supply chain management.

And back then, while choosing my masters, a new track, Aerospace Management and Operations, had just started. It fit with what I liked to do. I wanted to have a sustainability annotation on my diploma. That required me to do a few sustainable courses. I chose a few, one was recycling which was possible at that time.

I also needed to do an end-thesis project on sustainability.”

“How did you get the idea to start your own company?”

“I did an internship with Boeing, for research on carbon fiber recycling. After coming back from the US, I found a place with KLM engineering-maintenance to investigate the problem of a stranded Boeing 747 at Schiphol.

During my end-thesis, KLM-maintenance engineering was developing solutions for that specific aircraft. However, the owner of the airplane came back into the picture and they wanted to take their plane apart. KLM needed somebody to cooperate with the owner 58

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of the airplane and the company to be hired to disassemble and dismantle the airplane.

Ensuring that the job was carried out in the correct manner and there was no negative impact for KLM. I was allowed to manage this project. The Boeing 747 was disassembled and dismantled at Schiphol airport and I was partly managing the operations. Thereafter, I proposed a business plan regarding end-oflife solutions for airplane, but KLM insisted that their business was to fly airplanes. That’s when I said, “Then I will do it myself”. So, I started my own company straight after my graduation in 2005.”

“How do you get your hands on the aircraft?”

“We used to disassemble and dismantle the airplanes of airlines, and then return the components to the airlines or spare parts companies. But in 2012, we also decided to buy the airplanes ourselves. We got the first one in January 2013, with more to follow. We look for airplanes in the market that are marked for sale by airlines or lessors. “

“How many people do you have working in your company?”

We are now with ten people. We don’t have our own mechanics. When we disassemble an airplane, we employ mechanics that are specially trained and have knowledge about that specific aircraft model. We have a pilot; two fresh HBO graduates from InHolland Aviation Studies in Amsterdam, somebody in the warehouse that used to work for Transavia, two aviation enthusiasts; because you need to be a bit of an aviation enthusiast to

like this work. So there’s a lot of diversity, but everybody has something special to offer in Aviation.

“When you look for an aircraft to dismantle, how do you value it and how do you know if it’s profitable?”

“The revenue or the profit on a project you can only realize at the end. But the expectations are based on experiences on similar projects we have done in the past. What we offer is very simple; we get a list of the parts on the aircraft, we valuate those parts based on similar parts in the past or related information we have collected. We add it up and get a number, then from that number you subtract your cost and profit you want to make. Then we have an offer for an airplane. Hopefully, the seller is happy with that quote.”

“Have you made any judgment errors in buying these aircraft?”

“We have bought eight aircraft by now and only one of them is an underperforming project. I am not saying that all of them are slamdunk and easy money. It still requires a lot of work but so far, they have been good investments.”

“Can you tell us the step-by-step process of disassembling an aircraft?”

“After an airplane arrives at the airport in Woensdrecht, firstly, the engines are tested and often are removed and signed straight off so they can be used on another airplane. After that, we remove all liquids from the airplane, such as fuel and hydraulic liquids. Thereafter,

we start removing components. The parts that can be reused are sent to a certified repair station where they are inspected, repaired and overhauled in such a way so they can be used later on another airplane. The last thing that would go is the landing gear. This puts an end to the disassembly phase. It is followed by the dismantling phase, where all the light, non-positive value materials are removed which cause problems in recycling, such as plastics, isolation blankets. Dismantling phase ends with the big excavator with hydraulic scissor on top that cuts the airplane into small-

call stockists of parts, who manage a pool of components to support a fleet of airplanes.

They offer ‘power by the hour’ agreements. For a fixed rate, they guarantee the airline an availability of spare parts so that they will be able to continue operating the aircraft. An advantage for the airline is that they don’t have to invest in the infrastructure to warehouse and control spare parts. The third customer type for us are repair stations. These are companies that can re-certify the parts and some of them keep a stock of those parts as a replacement part. So, if the pump in the airplane breaks down, one

“When you look at the life cycle process, you consider also the benefit of using composites in reduction of structural weight, which is so significant that the end-of-life recycling issue is considered as a drop in the ocean.”

“Can these materials be used for aircraft again?”

“No, unfortunately not. The components can be, so the reuse is valid and it is a unique process that other industries are very jealous of.

Other industries call it remanufacturing. We just call it everyday business, I guess. With metals, like the stockpile of Aluminium that you end up with, it is not technically and economically feasible to sort all the different alloys from an airplane in such a way that you can melt them and end up with one alloy that can be used in production again. Quality demanded from production material is so high that if you start with an unknown mix, it is very hard to get to the level of quality required by the Original Equipment Manufacturer (OEM), like Airbus and Boeing. There are technical solutions but those are not developed enough yet or are far too expensive. If you have two Aluminium alloys, you get extra value for your good alloys and less for the ones with lower quality.

But the investment of energy and cost for the machine that carries out this sorting, needs to be earned back which ends up as a quantity challenge. There is simply not enough aircraft end-of-life aluminium in the market to make such a process optimal.”

can call them and a new pump is delivered and installed on the aircraft. In the meanwhile, the other pump is restored and the exchange is carried out again. The fourth customer base is what we would call brokers; they buy and sell parts on a part-by-part basis without doing any strategic warehousing or stocking. Of course, there are companies that combine all of those things. Aside from parts, there are the customers that buy our materials, like aluminium or steel. Then we have our clients who use our services: We disassemble and dismantle airplanes for other customers. Lastly, there are clients for alternative re-use; the sale of items from airplanes that people make something else out of than it was originally intended for.

For example, creative designers that turn a

“Can you tell us something about the ratio between the income from components and the materials?”

“The value of an airplane highly depends on its model and also where is it in its life cycle. For example, Boeing 737 is still being produced, thus the demand for spare parts is increasing.

The value of the parts of an airplane that is still in production can easily go more than 1000 times higher than the value of the rest of the airframe. When the production stops, with time more and more parts are going to be available at the market. Thus, availability increases and at the same time, the demand decreases. In those cases, the metal airframe value might be also the only profitable part of the aircraft.

These are the extreme scenarios. In general, if you look at 737 classics’ scrap value, which we are mostly interested in, then the ratio can go from 10 to 15 in favor for the parts.”

“At the moment, the aircraft you are recycling, are made of Aluminium. How do you think that would change in the future? Would there be more composite aircraft that need to be recycled?”

“We already get airplanes that have composites, with some A340s, A320s having an increased amount of carbon fiber in the bulkhead or the elevators or even complete tailplane in some cases. That is already a problem. The market of CFRP recycling is very AELS

er pieces. These are then put into a container and shipped to a recycling facility. It is further chopped into smaller pieces by a shredder.

Then the pieces are processed to separate different metal types from each other.”

wing into a table. On the more professional side, there are plenty of examples, such as cockpits which are re-built into cockpit simulators, doors which are used for cabin personnel training, and our disassembled airplanes are even used for training by fighters or even Special Forces, who train for how to enter an airplane in case of a hijack. Blowing doors out and stuff like that!”

“Who do you actually sell your components to?”

“There are many different groups of customers. The first group is airlines; as during maintenance, airplanes require components to be replaced. Secondly, there are what we would

Fokker F27 cockpit section, currently used by the Faculty of Aerospace Engineering at TU Delft as a study object.

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limited. There are no other industries using CFRP in the quantities that we do. Aluminum is used all over the place so the recycling business is big. Currently the recycling processes of CFRP, results with some kind of a very short fiber product, which nobody is interested in buying. Thus, all the recycling of CFRP results in a lot of waste. Additionally, when you disassemble an aircraft, the material that you result with is not pure. This is not only true for metals, but also for composites. It is going to be challenging. We are currently joining research groups that are working on the topic.”

“Could we then say that composite aircraft are less sustainable?”

“No. When you look at the life cycle process, you consider also the benefit of using composites in reduction of structural weight, which is so significant that the end-of-life recycling issue is considered as a drop in the ocean.

There is an interesting debate. Who is responsible for the way we deal with an end-of-life airplane? Is it the final owner of the aircraft?

Is it the company that operated it? The manufacturer? In my opinion, it is all of the above mentioned and everybody should contribute to a decent end-of-life solution.”

managed here in Europe.”

“Are there many companies like yours worldwide?”

“We have competitors but we are unique because we cover all elements. We disassemble the aircraft, remove everything that has the potential of reuse, so that we can recycle it, and we dispose the rest. We recycle the materials ourselves or in partnership under our own management. We control and manage the components that are removed. We manage the recertification or we certify it ourselves, we store them and eventually sell them. And we buy aircraft that go through the complete process. In this sense, we are the only company in the world that performs all this.”

“Globally, what would you reckon to be the potential demand for a service like you are offering?”

“Airbus and Boeing annually give out a twenty-year forecast. Each of them predicts that around 600 airplanes to reach end of life yearly in the more than 100 passenger aircraft segment. Is that number realistic? There is a continuous debate on that. I think we have a sort

“In this sense, we are the only company in the world that performs all this.”

“Where do you manage the process here in the Netherlands or in other locations as well?”

“We can do two things. Either they’re flown to our facility in Woensdrecht air base, where we have a concrete slab for disassembly. There are some cases that we prefer going to the aircraft. If the airplane can no longer fly or making it fly to our facility is going to be more expensive than us going there, provided that the position of the aircraft allows for a safe and effective process, then we perform our job there.”

“Due to the fact that Aerospace is in general global industry, do you think Netherlands is a strategically viable location?”

“Considering the selling of aircraft components, geographical locations do not really matter, apart of the transportation costs. With respect to buying airplanes, as long as they are still flying, the market for us is global. In theory, if they can fly to us, we can take them apart. 10 years ago we saw an increase in demand for EOL services in Europe, this was the reason we developed this company. At that point, we seemed to be right. In the past European airliners would sell their aircraft to others in South America, Middle East, Asia. These airlines are now buying a lot of new aircraft.

Thus, lately, more and more EOL aircraft are 60

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of a feeling of how the market develops and how things change over time with respect to the value and marketability of airplanes. I think that there will be enough potential to buy assets that we want to buy. Still, nobody knows how the future will be.”

“What are your plans for the future?”

“Our ultimate goal is to process 12 airplanes annually including engines by 2020. We are currently doing older generation 737s and A320s, and we want to move to the current generation and they are more expensive. But, because newer models are being introduced in the market, the A320neo and the 737MAX, production of the current generation stops. So the development we were just discussing will happen for those airplanes. And the amount of airplanes produced of this generation is much higher than that of the previous generation. There were 1700 737 classics manufactured, but we’re now already at more than 5000 737NGs. For the A320 you’re looking at 6000 aircraft in total, and they will continue production so there will be 7000 airplanes in the market. We want to do 12 annually.

Should be possible, I guess. Also, we want to introduce engines to our capability as well.

Currently we don’t invest in them. So that’s our growth plan, and that will probably triple the amount of workforce and our profits will go skyrocketing. My Toyota will be replaced with a Ferrari in the future!”

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SIEMENS

WIND ENERGY

FLOATING WIND TURBINES

Can the hope for a greener future be found in the deep blue?

Kumayl Sarwar, MSc Graduate, European Wind Energy Master (Rotor Design)

MARKET OUTLOOK Compared to land, offshore installations have a higher energy yield and availability due to the better wind resources and fewer noise restrictions. However, the infrastructure and supply chain required to develop ‘current’ offshore technology drives the cost of energy per kW much higher than for onshore wind power. The accompanying financial risk is a prime reason why only 33% of the planned wind farms, for EU 2020, are online today. The expenses entailed with the fabrication, transportation and installation of large offshore substructures, along with the turbine, are not 62

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balanced by the increased energy efficiency of offshore wind farms. According to a report from Bloomberg [1], the levelized cost of energy for offshore wind needs to reduce more than 45% to reach the 2020 target of €100/ MWh. Consequently, this sharp increase in the cost of energy can be seen as a consequence of increasing distance from coast and water depth for future projects.

CURRENT STATE OF TECHNOLOGY Conventional foundations consist primarily of a combination of monopoles: gravity based, jackets and some tripod structures. To exploit

The classification of the floating substructures concepts is dictated by the stabilizing element of the system. As shown in Figure 1, the distinctive floating platforms comprise of the spar-buoy, the tension leg platform (TLP) and the barge concepts which are - ballast, mooring and buoyancy – stabilized, respectively (Jonkman, 2009). However, numerous hybrid configurations composed of the innovative

PRINCIPLE POWER

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ffshore wind is a young industry, representing only about 10% of the annual wind installations across Europe (EWEA, 2013). Offshore wind farms are predominantly installed, with bottom fixed foundations, in waters mean depths of 25 meters and an average distance of 29 km from shore..

The cost ineffectiveness of current offshore designs in deeper waters is a limiting factor for offshore wind development in wind rich zones such as the Mediterranean, along the Norwegian coast, the Northern Atlantic and along most of USA and Japan’s shores. The need to sustain the proliferation of offshore wind is driving research to find innovative solutions adapted from the oil and gas industry, such as Floating Offshore Wind Turbines (FOWT).

the offshore wind resources more effectively, deep offshore designs are needed. In a rough analysis by [2], utilizing the offshore zone in the North Sea alone for depths greater than 50m with 3MW turbines could result in meeting double the EU’s current electricity demand. Possibilities like these have incentivized an exponential growth in the research on floating turbine concepts over the past years, with many projects now entering the prototype and pilot testing phases.

Compilation of various FOWT pilot projects currently in the development or pilot phase

GUSTOMSC

To supplement the vision of de-carbonizing our atmosphere, the continual growth of the offshore wind sector is a necessary ingredient. With more than 70% of the Earth’s surface covered in water, the immense opportunities laden in floating wind technology are no longer an unrealizable idea. The surge of pilot projects based on accelerated research collaborations, is quickly leading to the prospect of these gigantic machines floating in the vast deep blue waters.

In 2009, StatOil installed the first grid-connected 2.3 megawatt FOWT (Spar-buoy), called HyWind off the shore of Norway. Spar-buoy floaters are deep draught cylindrical structures with a large inertia due to the high ballast mass. This pulls the centre of gravity of the entire structure below the centre of buoyancy, keeping the turbine intrinsically stable, while a catenary mooring system maintains its position. The HyWind project is currently entering the demonstration phase with a larger installed capacity. In comparison, a TLP floating turbine has a highly buoyant substructure which is stabilized by taut wires attached to the sea floor. A combination of these concepts is implemented in the WindFloat FOWT installed off the coast of Portugal in 2012. It comprises of a semi-submersed tri floater assisted by a taut mooring system. Other key FOWT projects include Sway A/S, WindFlo, and VertiWind. The total tally of deep water projects under development or in the pilot phase across Europe, Japan and the US are over 40 [2].

OBSTACLES TOWARDS THE COMMERCIALIZATION OF FOWTS Although each concept has its respective pros and cons, replicating a FOWTs performance requires a robust tool which can accurately simulate the coupled dynamic response. A leading institute actively involved in the experimental evaluation of FOWT projects is the “Maritime Research Institute Netherlands”. With their various model tank facilities and a 5MW scaled model test turbine, floater designs can be verified with experimental results as well as simulated over a spectrum of environmental load cases with state of the art numerical codes.

Current wind turbine design tools mainly employ aero-servo-elastic codes which couple the aerodynamics and structural dynamics to the controller response. However, linear/ non-linear hydrodynamic influences and reactions from the mooring system, for a top heavy structure, add more layers of complexity and require simulations in the time-frequency domain. Demonstrating technical feasibility involves designing the system’s natural frequency within the wave spectrum where the dynamic response can be minimized. This, however, can vary based on the wind turbine design and site topology, leading to varied dynamic modal optimization.

Designing a lean stable floater which does not excite the structure with large accelerations and understanding the uncertainties within the mooring system are key focus points of FOWT research. The wave motion induces rotations in more degrees of freedom, making the aerodynamics more complex, thus reducing the efficiency of the turbine and potentially its fatigue life. Above rated wind speed, typical controller responses lead to a loss of rotor

NREL

combinations of these systems are emerging today.

Figure 1 - Floating Platform concepts for Offshore Wind Turbines thrust which can have negative impacts on the fore-aft motion damping, especially if the controller is not specifically designed to damp out the motion.

Apart from the turbine technology, the support infrastructure required for offshore installations poses a substantial challenge. Grid connection and suitable grid coupling points remain bottlenecks for offshore wind in general. Still, for FOWTs, the internal grid connections are also a challenge because of the additional loads from a moving platform inflicted on the cable and the complications/costs inherent with deep sea-bed array installations.

Validated modeling tools and numerical codes, minimizing platform motion, specialized controller designs, deciphering mooring system influences and light weight rotors are all important research topics feeding into the development of FOWT technology. Moreover, the experiences transferred from the oil & gas sector prove to be an asset; both with respect to floating structure design and mooring technology, along with the expertise in the complex offshore project execution.

FO-VAWTS? As an alternative, this graduate project was focused on investigating the Leveled Cost of Electricity (LCOE) for floating vertical axis wind turbines (FO-VAWTs) with respect to the DeepWind concept. VAWTs suffered from a lack of research and commercial interest after some early failures in the 1980s, resulting in the technology being less developed than its traditional horizontal axis counterparts. However, a lower centre of gravity, fewer moving parts and potentially easier platform access can translate to advantages in support structure capital expenditures (CAPEX), as well as

lower maintenance costs. These advantages are seen to be more evident for larger power ratings, rendering a better LCOE scaling for floating multi-megawatt VAWTs. Currently, pilot projects in France (VertiWind, Nenuphar) and the Netherlands (Spinfloat) along with research directives by Sandia Laboratories, the Technical University of Denmark and TU Delft are focused on solving a labyrinth of riddles to create more interest for this innovative concept.

FINAL THOUGHTS Cost reduction is the foremost challenge facing the offshore wind industry. The difference in Balance of Plant (substructure and site infrastructure) and installation costs potentially convene FOWT as a cheaper solution. In parallel, integrated design optimization of the wind turbine and the substructure, along with enhancements in port production/staging capabilities, a matured supply chain and optimized system architecture, can result in large reductions for the LCOE for deep offshore technology. As the penetration of offshore wind continues to surge, solutions for deep water sites are an inevitable consequence.

Innovative research, industrial synergy and energy necessity can ensure the sustenance of this emerging technology.

References [1] Bloomberg New Energy Finance. (2013).

World Energy Perspective: Cost of Energy TechnologiesOC. World Energy Council.

[2] EWEA. (2013). Deep Water - The next step for offshore wind energy.

[3] Jonkman, J. M. (2009). Dynamics of offshore floating wind turbines—model development and verification. Wind Energy , 459492.

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FPP 64

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HIGH-FIDELITY PROPELLER TESTING AT DNW LLF

Towards silent and more efficient propeller propulsion systems

Tomas Sinnige, PhD Candidate at the Flight Performance and Propulsion section Ever since the first flight, propeller propulsion has played an important role in aviation. Advancements in performance at high subsonic speeds have renewed interest in the application of propellers on future transport aircraft, making advanced propellers an active topic of research. In this context, a two-week experiment was performed at DNW LLF by a European research consortium led by TU Delft’s FPP chair, focusing on pusher propeller installation effects.

A

fter the advent of the jet engine in the 1940s, the desire to achieve higher flight speeds motivated civil transport aircraft manufacturers to shift from propeller-driven to jet-powered aircraft. However, increasing air traffic and environmental awareness currently stimulate the aircraft industry to develop more fuel-efficient aircraft. Considering that the higher propulsive efficiency of propellers compared to turbofans promises a reduction in fuel burn of up to 25%, there is a clear incentive for airframers to evaluate propeller propulsion for application on future aircraft. One of the major challenges to overcome for successful integration of propellers is posed by the interaction effects associated with installation of the propellers to the airframe. Compared to the isolated case, in the installed configuration both the aerodynamic and aeroacoustic performance of the propeller are affected, leading to reduced efficiency and increased noise emissions. The reduction of these installation effects forms one of the topics of research at the Flight Performance and Propulsion (FPP) section of TU Delft’s Aerospace Engineering faculty.

verse interaction effects associated with the presence of the pylon upstream of the propeller disk. In addition to the pusher propeller installation tests, also a full test day was devoted to the assessment of a technology to further increase the efficiency of the isolated propeller.

PYLON — PUSHER PROPELLER INTERACTION EFFECTS For pusher propellers installed at the rear part of the fuselage, the main source of installation effects is the presence of the upstream pylon used to connect the propeller to the airframe.

The reduced velocity in the pylon wake leads to a non-uniform inflow field impinging on the propeller disk. While rotating through the wake, the propeller blades experience a rapid change in angle of attack. This results in fluctuating blade loads, which directly affect the propeller performance and increase the noise emissions. One way to reduce the py

THE APIAN-INF EXPERIMENT As part of this ongoing research, in September 2014 a two-week wind tunnel test was performed at the Large Low-speed Facility (LLF) of the German-Dutch Wind Tunnels (DNW) to investigate the installation effects associated with pusher propellers, connected to the rear-fuselage via a pylon. Part of the EU-funded ESWIRP project, the experiment (named APIAN-INF) involved contributions from a research consortium consisting of Airbus, DLR, DNW, INCAS, TsAGI, TU Braunschweig, TU Delft, and the University of Cambridge. From the TU Delft side, apart from the FPP chair, the Aircraft Noise & Climate Effects and Aerodynamics chairs participated in the test activities.

Featuring an 8x6 meter outlet, the test hall of the LLF measures approximately 50x30x20 meters and is treated with acoustic lining to result in a semi-anechoic environment. A six-bladed, 0.5m diameter propeller model was used together with a TU Delft in-house designed and manufactured pylon model.

The pylon included a trailing edge blowing system, which was used to mitigate the ad-

Figure 1 - Velocity profiles directly upstream of the propeller for the cases with pylon blowing on and off, and the isolated propeller.

Figure 2 - Change in propeller noise levels due to installation of the pylon, with and without pylon blowing.

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lon installation effect is to fill the pylon wake by means of pylon blowing. In this way the velocity deficit in the pylon wake is cancelled, thereby eliminating the interaction effects. The pylon blowing system can be integrated in the pylon in various ways; in this case, air was blown through a slit in the pylon’s trailing edge.

Measurements using Particle Image Velocimetry (PIV) confirmed that the application of the blowing system indeed reduced the velocity deficit in the pylon wake, as shown by the velocity profiles extracted from the PIV data displayed in Figure 1. At the optimal blowing rate,

fluctuating blade loads lead to an additional tonal noise component: unsteady loading noise. Figure 2 shows the measured noise penalty due to the presence of the upstream pylon for the cases with and without pylon blowing, relative to the isolated configuration without pylon. Since propeller noise is characterized by a clear directivity pattern, the changes in sound pressure level are plotted versus the axial directivity angle θ. Figure 2 confirms that the reduction in velocity deficit in the pylon wake due to pylon blowing indeed reduced the impact of the pylon installation

efficiency. When fixing the second blade row an efficiency gain can still be achieved, however without the added complexity associated with contra-rotating systems. In the early nineties, NASA studied such a configuration with research partners (see e.g. [Gazzaniga and Rose, 1992]), who introduced the term swirl recovery vanes (SRVs). As a first step in the ongoing research on SRVs at the FPP section, one test day of the APIAN-INF experiment was devoted to the assessment of the aerodynamic and aeroacoustic effects of SRV installation behind an advanced single-rotating propeller. For this purpose, a set of five SRVs was designed at TU Delft using a numerical optimization routine based on low-order propeller analysis methods. Since the SRVs were not instrumented, it was not possible to directly quantify the gain in thrust, hence propeller efficiency, obtained by their installation.

However, PIV measurements of the isolated propeller’s slipstream with and without swirl recovery vanes confirmed that the SRVs indeed reduced the swirl in the propeller slipstream.

Figure 3 displays the ratio of the kinetic energy of the swirl components relative to that of the freestream for both configurations. It is concluded that application of the SRVs resulted in a reduction in swirl kinetic energy of up to about 60%, thereby potentially enhancing the efficiency of the propulsion system. Note that for acoustic reasons the SRVs were cropped relative to the propeller diameter, hence in the outboard part of the rotor’s slipstream the flow is not affected.

CONCLUSIONS AND OUTLOOK

Figure 3 - Swirl kinetic energy contours in the propeller slipstream with and without swirl recovery vanes. the integral velocity deficit in the pylon wake was decreased by approximately 80% compared to the unblown case, leading to a nearly uniform velocity profile.

With the significant reduction in the pylon wake velocity deficit with pylon blowing enabled confirmed, the impact of the installation effects on the noise emissions was assessed.

Propeller noise consists of a combination of tonal and broadband components, with the tones dominating the sound spectrum at lower frequencies. For the isolated propeller the two main sources of tonal noise are loading and thickness noise, emitted at frequencies equal to multiples of the blade passage frequency (rotor rotational speed times number of blades). In the installed configuration, the 66

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effects. Whereas for the unblown case an increase in sound pressure level of up to almost 12dB is observed, the configuration with blown pylon emits approximately the same noise levels as the isolated propeller. In other words: the installation effects due to the presence of the upstream pylon were completely eliminated by application of pylon blowing.

SWIRL RECOVERY VANES To maximize the propulsive efficiency of already favorable single-rotating propellers, Contra-Rotating Open Rotors (CRORs) seem to be an interesting solution. The ability of the CROR’s second blade row to recover the swirl (i.e. the tangential velocity components) in the slipstream of the upstream rotor can yield a substantial increase in the propulsive

A two-week wind tunnel test campaign was performed in the LLF at DNW in the EU-funded ESWIRP project. The experiment focused on pylon – propeller interactions for aft-fuselage mounted pusher propellers. It was shown that the application of pylon blowing eliminates the adverse installation effects experienced in such a configuration, with noise reductions of up to 12dB compared to the unblown case.

This is a direct result of the reduction in velocity deficit in the pylon wake due to blowing. For the isolated propeller it was shown that the application of swirl recovery vanes reduced the swirl in the propeller slipstream by up to 60%, thereby potentially enhancing the propulsive efficiency. Building upon these promising results, future research will be performed at the FPP chair to explore the propeller installation effects in even more detail.

For more information about ongoing propeller research activities, including opportunities for MSc graduation projects, please contact the author at T.Sinnige@tudelft.nl.

References [1] Gazzaniga, J.A., and Rose, G.E., 1992.

“Wind tunnel performance results of swirl recovery vanes as tested with an advanced high speed propeller”. 28th Joint Propulsion Conference & Exhibit, Nashville, TN, USA.

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PHYS.ORG

ASM

DESIGNING NEW STEELS FROM SCRATCH

Artificial intelligent design of high performance heat resistant steels

Qi Lu, PhD researcher, Wei Xu, assistant professor, Sybrand van der Zwaag, professor Novel Aerospace Materials, Faculty of Aerospace Engineering, Delft University of Technology High performance metallic alloys are traditionally designed by an experimental trial and error approach taking existing alloys as the starting point. The approach works but is costly and slow, leading to stepwise improvements at best. TU Delft researchers recently developed a computational approach dedicated to the design of novel creep resistant steels, coupling thermodynamic and kinetic mechanisms and combining a genetic algorithm. Using this approach, the alloy design cycle time can be significantly reduced.

S

teels, alloys of iron and alloying elements such as carbon, chromium, nickel and manganese are widely used in many demanding applications owing to their high performance. Some steels have to function under harsh conditions, such as high temperature, aggressive chemicals and high load (still below the yield strength of the steels). When exposed to such conditions for a long time, a phenomenon called creep will occur. Creep is the process of a continuously increasing permanent deformation under a more or less constant load at a high temperature (> 500°C) for a long time (>10 years). Creep beyond a certain deformation can cause serious problems, for example, creep of an engine turbine blade will cause the blade to contact the casing, resulting in the failure of the blade. To avoid this problem, various creep resistant steels have been developed. The design of creep resistant steels is based on the creation of nano-sized ‘obstacles’ which slow down the displacement of dislocations responsible for the permanent deformation with time (see Figure 1). Solution strengthening (i.e. replacing iron atoms by bigger alloying chemical elements) and precipitation hardening (i.e. the creation of nanostructures composed of carbon, nitrogen and other chemical elements), are the principle metallurgical design tools. Alloy de68

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sign is the art of determining which alloying elements (and in which concentration) need to be added to the steel composition such that the (creep) strength goes up and unwanted side reactions are prevented. Typically up to ten alloying elements are considered simultaneously and concentrations are specified at 0.1wt% level or finer.

Traditionally, alloys are designed by an experimental trial and error alloy approach, which involves a large number of process-structure experiments and modelling to understand structure and properties of candidate microstructures. The trial and error approach generally starts from a known reference alloy and hence this approach may (only) realize small stepwise improvements at best and at a low success rate, since a small change in the design not always leads to an improvement, but can also eliminate desirable properties.

Moreover, the design cycle may be extremely long and costly for a new material which is to be used in applications with an intended life time of ten years (such as turbine engines and reactors for conventional or nuclear power stations).

On the other hand, a remarkable development of computational techniques during the last decades has made the computational

design of new alloys feasible, both technically and economically. From a computational perspective, the performance of a material is determined by both its ‘genome’ (inherent property, e.g. composition) and its ‘experience’ (external interactions-processing-condition during usage). Various computational approaches aiming to accelerate the design of new alloy systems have been explored successfully, for instance, computational thermodynamics, artificial neural networks (ANN) and ab initio calculations. All these computational methods can provide very valuable information and hence guide and accelerate the exploration of new alloy systems.

Genetic algorithms (GAs) are biologically inspired computing techniques, which tend to mimic the basic Darwinian concepts of natural selection. They are highly robust and efficient for most engineering optimization studies. Although a late entrant in the materials arena, GAs based studies are increasingly making their presence felt in many different aspects of this discipline. In recent times, in a ‘metals by design’ project GAs have been successfully combined with thermodynamics to design

Figure 1 - Schematic illustrating the mechanisms of solid solution strengthening and precipitation hardening [1].

a large number of attractive solutions with different combinations of SSS and PH. In the future, additional criteria such as cost, weldability, processibility etc., can be added as extra criteria to filter the solutions on the current Pareto front. Whatever these additional filters, the current results as summarized in Figure 2 suggest that there is still a substantial potential to improve the long-term creep strength of current creep resistant stainless steels.

Figure 2 - The (105 h, 650°C) PH and SSS factors for the newly designed alloys and for existing creep resistant steels [2]. advanced ultra-high strength stainless steels for room temperature applications by NovAM group at the TU Delft Aerospace Engineering Faculty. Although this project only lasted for four years, the newly designed alloys outperformed those of related commercial alloys with a typical development time of more than ten years. NovAM recently extended this approach to design creep resistant steels for high temperature applications explicitly taking into account the effects of time and temperature on the creep resistance.

In our extended computation design approach, an optimal combination of precipitation hardening (PH) and solid solution strengthening (SSS) contributions is achieved using the following method. A genetic algorithm is applied as the optimization scheme, taking into account ten variables (nine alloying elements and the austenisation temperature) uniformly distributed over 32 levels between predefined minimal and maximal values for each variable, yielding in total 3210 candidate solutions. The PH and SSS contributions of a solution will be predicted by using thermodynamics in combination with physical metallurgy principles. As the units of the PH and the SSS optimization factors are different, the predicted strengthening contributions are

not simply numerically additive. Hence, the PH and SSS were first optimized independently.

Then, all qualified solutions from the two independent optimizations are plotted together as PH versus SSS, from which a ‘Pareto front’ can be constructed, as shown in Figure 2. A Pareto front is a curve where the crucial information for two non-compatible properties is presented graphically. From the curve one can derive the best possible trade-offs between PH and SSS. In order to benchmark the newly designed alloys against existing alloys, the SSS and PH calculations were repeated for the compositions of some existing creep resistant steels currently on the market. The results are shown in Figure 2. The green dots are solutions derived using the authors’ computational alloy design approach. All solutions on the Pareto front are predicted to outperform existing alloys not only in PH factor but also in SSS factor. Moreover, existing alloys seems to display a direct competition between the PH and SSS factors, i.e. SSS increases at the cost of PH. The target of the present investigation was to find a better trade off with a simultaneous optimization of both factors, leading to an optimal combination solution (PHSSSR) as indicated by the arrow. Finally, the Pareto front presents

Alloying element types and concentrations determine PH and SSS contributions, and eventually the location of the Pareto front. To illustrate this dependence, the graphs in Figure 3 show the dependence of the Pareto front on Ni and Nb concentrations, taking other element concentrations as for the optimized alloy PHSSR. Figure 3a shows that Ni has a great capacity to improve SSS without sacrificing PH, as shown on the nearly horizontal part of the Pareto front. Higher concentrations of Ni are necessary to achieve a better combination of PH and SSS, but very high Ni concentrations destroy the PH contribution to the creep strength. In Figure 3b, relative low concentrations of Nb keep the PH contribution at high levels on the nearly horizontal part of the Pareto front. Low concentrations of Nb stimulate positive effects on PH contributions and higher concentrations have a negative effect.

The NovAM department is currently working on the validation of such a computational design approach. Novel alloys with composition and heat treatment parameters chosen from the Pareto front have been fabricated in China and are currently being tested. The preliminary results are quite promising.

References [1] K. Lu, L. Lu, S. Suresh, “Strengthening materials by engineering coherent internal boundaries at the nanoscale”, Science, 324, pp. 349-352, 2009.

[2] Q. Lu, W. Xu, S. Van Der Zwaag, “The design of a compositionally robust martensitic creep-resistant steel with an optimized combination of precipitation hardening and solid-solution strengthening for high-temperature use”, Acta Mater., 77, pp. 310-323, 2014.

Figure 3 - Concentration effects of (a) Ni and (b) Nb on the Pareto front. All concentrations are weight fractions.

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EXPLORING HUMAN-LIKE AUTOMATION IN ATM

Human-Automation interaction research

Carl Westin, PhD Student Aerospace Engineering In the Air Traffic Management (ATM) domain, automation is expected to enable the necessary traffic capacity that is needed to meet the future demand for air travel. However, introduction of increasingly sophisticated automation is at the risk of being rejected, and threatening the required growth. This article discusses ongoing PhD research that is exploring the benefits of individual-sensitive automation capable of solving conflicts between aircraft as intelligently as an air traffic controller.

EXPLORING AUTOMATION BIAS

agent as human, when in fact it is a computer.

According to several leading scientists (e.g.

Hawking et al., 2014), achieving true AI (also known as point of singularity or transcendence) is not a desirable step in evolution, drawing up a dark and doomsday-like future where machines take over the world and decide to eradicate the inferior and error-prone human race. Perhaps luckily then, to date, only a single computer has passed the Turing test and we have not realized in any meaningful way the highest levels of autonomous systems. Others are less pessimistic, foreseeing a world where human and machines live and work together and live happily ever after.

WESTIN

We have reached a crossroads in automation evolution where everyday technology is maturing from replacing physical tasks to assuming more and more of the “thinking” cognitive tasks previously performed only by humans. Given the current development of machines and what they are capable of, it seems possible that one day machines will match and even exceed human intelligence.

The ultimate test for artificial intelligence (AI) was posed roughly sixty years ago by English mathematician Alan Turing: a computer can be said to really “think” when one can converse with an unseen agent and perceive that

Figure 1 - Graphs illustrating the spread in resolution strategies across 16 participants, used to solve conflicts in two different scenarios. Here the strategies are divided into three categories depending on the resulting conflict resolution used: change in heading, speed, or combination of both.

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Looking beyond the philosophical and moral concerns of AI, the possibility of automation as intelligent as a human being poses an interesting thought: What if we could create automation that thinks and solves problems exactly like a human, would the human more readily accept its advice? Or would the human reject the proposed solutions simply because it came from a machine? In other words, is there a dispositional bias against working with automation?

THE MUFASA RESEARCH In essence, these questions drove the Multi-dimensional Framework for Advanced SESAR Automation (MUFASA) project that started in 2011 and subsequently laid the groundwork for an ongoing PhD research initiative. The MUFASA project explored these high-level questions in the context of Air Traffic Management (ATM). The ATM domain is an example of a high-risk, stochastic, dynamic, and complex environment where human and machine work closely together to achieve a common goal. The demand for air travel is pushing the envelope for what the current ATM system is capable of handling without applying restrictions on the flow of traffic. Predictions of future growth in the skies show that fundamental enhancements and changes are needed to modernize the close to saturated ATM system. One of the key areas in this process is the increased dependence on automation. Not only is automation expected to perform more of the routine air traffic controller tasks, but increasingly oversee aspects of more strategic and cognitive tasks, such as conflict detection and resolution. Progressively, automation is primed to mature into a team member and colleague rather than a device or tool. However, evidence from a variety of fields, including

ATM, has highlighted operator acceptance as potentially one of the greatest obstacles to successfully introducing new automation.

Without acceptance, the potential safety and performance benefits of automation may not be achieved. One growing line of thought is that differences between human and machine in their problem solving styles create a mismatch that threatens the acceptance and use of sophisticated decision support automation. Researchers have addressed this issue by studying the cognitive qualities of air traffic controllers, extracting their heuristic decision-making processes, and attempting to model and package it as automation. While results have been promising, showing benefits to acceptance and automation use (for example Kirwan & Flynn, 2002; Lehman et al., 2010; Flicker & Fricke, 2005), these studies have not been able to ensure complete harmony between human and machine decision-making styles. In these studies, the human operators have been “chunked” together and treated as a homogenous single decision-making entity.

Consequently, the resultant automation becomes a “one size fits all” creation that forces adaptation from the human operator. Note that this assumption is true for the majority of technology applications. In contrast, is it not likely that human cognitive characteristics in decision-making vary individually just like human physical characteristics? It seems reasonable to assume that automation thinking and solving problems similarly to the human operator would benefit teamwork and team performance.

STRATEGIC CONFORMAL AUTOMATION BENEFITS AUTOMATION ACCEPTANCE Until now, the MUFASA project has, through a series of experimental human-in-the-loop simulations involving real air traffic controllers, produced some fascinating results in addressing this question. Instead of attempting (and certainly failing) to develop full AI to assure an underlying match in intelligence between automation and human, the MUFASA team developed a decision-support system that used conflict resolution performance from individual air traffic controllers to reverse-engineer decision advisories on how to solve conflicts.

Analysis of controllers’ conflict solution performance revealed large differences in conflict resolution strategies between controllers (Figure 1). In the largest trial, 16 Irish en-route controllers played a number of traffic scenarios supported by a decision support system that would suggest solutions to detected conflicts between aircraft. Controllers could, in real time, either accept or reject the suggested solution.

In half the cases, the solutions were a replay of their own solution to the same conflict, as WESTIN

The core task in ATM consists of safely directing aircraft from origin A to destination B without colliding with other aircraft. In the tactical sense, this is represented by the conflict detection and resolution task carried out by air

traffic controllers, whereby potential conflicts between two or more aircraft are identified and solved. In this specific context, the main research question of MUFASA was formulated: would controllers more readily accept advisories on how to solve conflicts between aircraft from an automated agent if those advisories were identical with how they themselves would solve the conflict? The measure of similarity in problem solving is defined as strategic conformance. This question is supposed to provide two important answers: the degree to which humans have a bias against automation, and if there are any benefits to individualizing automation.

Strategic conformance addresses the match in solution strategies between the individual human and the automation. If there is a match, the solution is considered conformal. If strategies do not match, the solution is considered non-conformal.

recorded in an earlier simulation. In the other half, the solution was derived from a colleague (who had chosen a different but workable solution). Data was analyzed to determine the influence of whether automation had matched controllers’ own strategy on factors such as acceptance, agreement, workload, and response time.

Not only did controllers accept and agree more with solutions that matched their own previous performance; they also responded faster to these solutions. These findings suggest that individual-sensitive automation can greatly improve automation acceptance and use. It underlines the important role that strategic conformance can have on the willingness to embrace new decision support automation, and that such automation should be further evaluated.

The presence of a dispositional automation bias has thus far not been established, but the noteworthy result in which controllers rejected their own previous solution in almost 25% of the cases (believing that it came from automation) warrants further inquiry into this matter. Would controllers have been more or less accepting if they had believed the source of the advice was from a colleague? Although possibly the high count of rejections is not at all indicative of a bias but can simply be attributed to inconsistencies in human problem solving and decision-making behavior. These and other remaining questions are currently being explored in an ongoing PhD research initiative.

Disclaimer: The initial MUFASA project was SESAR WP-E funded collaboration between Lockheed Martin UK, the Delft University of Technology (TUD), the Center for Human Performance Research (CHPR), and the Irish Aviation Authority (IAA).

References [1] Brynjolfsson, E., & McAfee, A. (2014). “The second machine age: Work, progress, and prosperity in a time of brilliant technologies”, New York, NY: W. W. Norton & Company Inc. [2] Hawking, S, Russell, S, Tegmark M, and Wilczek F. “Transcendence looks at the implications of artificial intelligence – but are we taking AI seriously enough?”, http://www.independent.co.uk/news/science/, May. 01 2014 [3] Kirwan, B and Flynn, M. “Investigating air traffic controller conflict resolution strategies”, EUROCONTROL, Brussels, Belgium, Rep. ASA.01.CORA.2.DEL04-B.RS, Mar. 2002.

[4] Lehman S, Bolland S, Remington R, Humphreys M. S, and Neal A. “Using A* graph traversal to model conflict resolution in air traffic control”, in Proc. 10th ICCM, D. D. Salvucci and G. Gunzelmann, Eds., Philadelphia, PA, Aug. 5-8 2010, pp. 139–144.

[5] Flicker R, and Fricke M. “Improvement on the acceptance of a conflict resolution system by air traffic controllers”, Baltimore, MD, Jun. 27-30 2005

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ASM

KISSING BONDS

Inspection of defective adhesive lap joint for aircraft applications Mirco Verze, Student MSc. Aerospace Engineering, ASM Chair, Faculty of Aerospace Engineering, TU Delft A kissing bond indicates an adhesive bond where the adhesion has degraded compromising the whole joint. Current inspection techniques fail at detecting this type of defective bond, which undermines the use of adhesive bonding in aircraft manufacturing. Recent researches involving Lamb waves could improve current adhesive inspection technologies and lead to improved aircraft designs.

LAP JOINTS Aircraft manufacturers use riveted lap joints as

BOND TESTER 600

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ften the amount of work that goes into the maintenance and inspection of aircrafts is not appreciated. An airplane is designed and certified to fly not once but numerous times. Strict regulation requirements on manufacturing and maintenance make air travel one of the safest modes of transport but implementation of improved designs is often a lengthy and costly process.

In the recent years, civil aviation has been undergoing a revolution of sorts. In fact, most recent aircraft are equipped with several on board sensors monitoring and assessing the structural soundness of each component. It is an ambitious idea but the reality is that some components, such as adhesive lap joints, are still hard to even inspect. Current technology cannot reliably determine if the adhesive in a joint is still good enough, which makes adhesive bonding quite hard to implement in large scale and primary structures.

This project, which started in September 2014 at TNO and is co-supervised by Dr. Kassapoglou from the Aerospace Structures and Computational Mechanics Chair at TU Delft, is focused on the development of a reliable inspection technique for adhesive metal lap joint.

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the standard joining method for bonding fuselage panels. Adhesive lap joints are also used, but limited to non-critical area. Adhesive and riveted joints, although geometrically similar, have completely different load transfer behaviors. While riveted lap joints concentrate the load in the rivets, adhesive lap joints transfer it across the whole adhesive surface. This leads to different behaviors in fatigue life, with adhe-

For these reasons, adhesive joints are very attractive contrary to the currently used riveted joints, but the lack of reliable and effective inspection techniques is still a major limitation.

Degradation and failure in adhesive joints is limited to the adhesive layer. Once the lap joint has been manufactured, it is practically impossible to inspect. This is clearly unacceptable from a safety point of view.

Inspecting riveted lap joints, on the other hand, is straightforward. Cracks develop around the rivets due to the high stress concentration.

They can safely be detected at early stages thanks to cost effective and reliable inspection techniques including eddy currents and dye penetrants.

KISSING BONDS ‘Kissing bonds’ is a term used to identify a defective adhesion with particular characteristics. Although there is no unique definition in literature, the following properties are undisputed: they are interface defects, which means that the adhesive cohesive properties are unaffected while the adhesion is lacking, they show close contact between adhesive and adherents, and they cannot be detected with current technology such as standard ultrasonic techniques. A kissing bond can originate in different ways. It can occur due to wrong surface preparation, degradation of the adhesion due to environmental exposure, or contaminations such as oil and grease.

Current inspection techniques fail at detecting a kissing bond reliably due to the fact that although it is an interface problem, there is no clear ‘jump’ in the properties while the adhesive and adherents are in close contact.

Partial solutions for inspection of adhesive bonds are available, such as the Fokker Bond Tester, which creates ultrasonic standing waves or pulse-echo through the thickness to determine changes in the cohesive properties or presence of contaminants. Other less conventional techniques have been implemented such as embedding coupons in the adhesive with one end sticking out. During inspection, pulling said coupons would determine the status of the adhesive. If the coupon breaks, adhesion is still good, but if it slides out then the adhesion has degraded and further inspection would be required. The joint mechanical behaviour, also known as the load-displacement curve has been used after a comparison with the baseline case; variations can then be related to properties degradation. A more common solution has been the implementation of “chicken” rivets.

Rivets are installed along with the adhesive as a fail-safe design; inspections on the rivets are carried routinely before damage reaches a critical size. It is assumed that the adhesive is not effective in carrying loads between limit and ultimate load. This solution, although increasing the efficiency of the joint, is still a limit to the full potential of the adhesive.

A NEW APPROACH In the recent years, solutions to the reliable bond-line inspection problem involving Lamb waves are being investigated. Lamb waves are tiny disturbances that can propagate in thin structures. The properties of the structure, together with the frequency at which they are excited, change the behavior of these disTNO

CURRENT TECHNOLOGIES Unlike mechanical joints, adhesive joints can-

not be disassembeled and reassembled. This makes the development of nondestructive inspections (NDI) a vital part for a widespread implementation of adhesive bonds in aircraft manufacturing. Current applications require careful preparation and standardized manufacturing processes, in order to ensure repeatability and consistent high performance.

Simulation steps of wave propagating in lap joint

TNO

sive joint showing higher resistance to cyclic loading. Additionally, since no rivets or bolts are involved, it is a much lighter solution.

Lab set up for ultrasonic measurements of defective specimens turbances such as wave speed. The nature of lamb waves is such that different wave modes exist; exhibiting frequency-dependent propagation properties, much like multiple simultaneous vibration modes of a structure.

Each wave mode has its own speed and cross-sectional displacement. In the literature, substantial research has been done on lamb waves, with successful implementations in the oil and gas industry where they are used to determine corrosion and sediments in long pipes.

The waves travelling through the lap joint can be tuned to interact with the defect at the adherent-adhesive interface. This means that these waves could behave differently on a perfect and a defective joint. This sensitivity makes Lamb waves good candidates for inspecting the presence of kissing bonds.

HOW WILL THIS BE ACHIEVED? Before going around airplanes and strapping lap joints with transducers, one has to spend a lot of time simulating and testing the hypotheses. In the past six months, the author used powerful simulation software based on a higher-order spectral finite element method, which allowed highly accurate and fast simulation for different wave modes and detection methodologies for kissing bonds. Eventually, these simulations led to optimal test architecture to confirm the results of the original hypothesis. Following this, the joints to be inspected and tested were manufactured at the TU Delft DASM laboratory. Industry standard processes and materials were followed for the manufacturing processes. Afterwards the specimens were inspected at the ultrasound laboratory at TNO. These measurements were very insightful and helped further improve the original approach. In the test results so far, it is possible to observe the expected variation between the perfect specimens and the defected ones. The final step will be to test the specimens to failure and see if the results from the inspection can be correlated to the strength of the joint.

CONCLUSION An ideal inspection method on any structural component should be able to identify defects and effectively and accurately predict its residual strength. Shear tests will be conducted in the following months, but good correlation is already expected between failure strength and measurements.

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TRANS-ATLANTIC CROSSINGS

Effects of climate change on the crossing

Raphael Klein, MSc Student Aerospace Engineering & Editor, Leonardo Times Every winter, new records are being established on trans-atlantic flights. From Europe, flights are delayed by increasingly strong jet stream winds while aircraft returning to the old continent are beating World speed records, reducing trans-atlantic flight times by over an hour and reminiscing of speeds only attained by the Concorde.

F

or the past several decades, it is a given for passengers that a flight from Europe to the United States does not need to stop for refueling. In recent winters however, more and more passengers have had the unwelcome experience of a forced stop in the north-eastern reaches of Canada and the United States before being able to continue to their final destination.

between the Equator and the poles becomes increasingly larger. This increase helps create the massive storms over large parts of the United States but also on the other side of the Atlantic, in Ireland and the United Kingdom.

These strengthened winds also have a large impact on transatlantic flights, and more specifically on flights operated on the Boeing 757.

CLIMATE CHANGE

Over the Atlantic, only one aircraft can currently help maintain routes between smaller cities in Europe towards the American hubs, largely unprofitable for bigger aircraft: the Boeing 757.

This is the only narrow-body (single-aisle aircraft) able to bridge America with the old continent (excluding the all business class A318s flying between London City Airport and New York JFK). Designed in the late seventies and built in the eighties, it is the workhorse of all major American companies for their transatlantic flights as well as Icelandair, which operates twenty-five of them. To this effect, US Airways operates fifteen of them, United more than seventy, American fifty and Delta around thirty. This aircraft allows American airlines to come to smaller western European destinations where an A330 or a B777 would provide excess capacity and be unprofitable.

“Snowmageddon” and polar vortex are two expressions that have been widely used when awaiting storms on the other side of the Atlantic. 24-hour news services fancy exaggerating weather bulletins. In the winter months of 2015, these storms have been particularly numerous, covering large swaths of the United States with record snow fall in Boston and leading to record low temperature in Chicago.

All these storms are caused, in part, by the so-called polar vortex or polar jet. The polar jet consists of winds in the upper levels of the atmosphere that circulate around the poles (there is a polar vortex over the South Pole too). When these winds reduce in intensity, large masses of cold air move southward which then leads to wavy polar jets, see a comparison in Figure 1. In other words, these winds retain the masses of cold air present in the poles. The jet stream picks up in intensity during winter as the temperature difference 74

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THE B757 AND THE ATLANTIC

These low passenger-count routes allow point-to-point travel for millions of passengers.

The 757 also plays a major economical role for US airlines that heavily rely on hub opera-

tions. These airlines do not only have one hub to feed, like European airlines, but instead can have up to eight hubs for their international flights (not all of which are on the US East coast). A prime example is the Delta hub operations from Amsterdam. On one side, Delta Airlines feeds its US hubs with six flights per day to its three hubs on the East coast. At the same time, it uses Amsterdam as a hub with 23 flights per day to a range of destinations within the United States. Similarly, United is using its 757 from Newark to expand its network, going to smaller destinations like Newcastle, England or Shannon, Ireland.

The smaller 757, compared to its counterparts, allows for much higher route frequencies. This is crucial on routes from London to New York where some airlines prefer having six flights a day with smaller aircraft instead of two large flights. This is also usually more attractive to passengers who can choose their flight depending on their schedule.

REROUTING AND RECORD FLIGHTS The Boeing 757’s size is not always advantageous. As mentioned earlier, the winds in the upper atmosphere, where aircraft fly, are fierce and one sided. The jet stream flows from West to East. In winter, these winds are much stronger, and wrecking havoc for all transatlantic flights, but even more so for the 757. In the winter of 2015, the impact was particularly large but this problem is a recurring one. Year on year, it increases the economic burden on airlines. The main problem is the stopovers.

The winds are so fierce that aircraft ground speeds are reduced significantly. The aircraft are then not able to reach their destination and have to make fuel stops in Goose Bay, Cana-

MIKEY LAMB

however discontinuing their longest routes in the winter and reintroducing them in the summer (this is also partly due to the summer holidays).

IN THE FUTURE

Boeing 757 of Icelandair. da for the most extreme cases, or in Bangor, ME, US which is further along the way. This problem sometimes extends to larger aircraft coming from further along like Eastern Europe or Scandinavia.

minutes. Such a flight usually takes around six hours to complete. The aircraft ground speed was close to the speed of sound although it was cruising at normal speed.

In 2012, Continental alone, with its fleet of Trans-Atlantic B757, had to make 43 unscheduled refueling stops during the winter.

At the time this article is being written, the final tally of aircraft that had to be refueled is not yet known, but the problem is still present and growing. This problem has been increased due to the large amount of winter storm above North America, fuelling the jet stream.

The routes most affected are the ones that are usually just within the 4,000 nmi (7,400 km) range of the B757. These high winds, which can reach speeds above 300 km/h, lead aircraft to fly much more north than they usually do, reaching the tip of Greenland to avoid the biggest chuck of the jet stream.

These unscheduled stops have an impact on the economy of these flights but also on the airports at which they land. Airlines have had to pay hundred of thousands of dollars in additional fuel costs to be able to sustain their flights. Additionally, they have had to provide compensation to the thousands of passengers who miss their connection flights when arriving in the States. To avoid stopovers, airlines try to cram as much fuel as possible on their way to the US and tend to forgo all types of cargo to be as light as possible. This has an impact on route profitability as some routes can carry significant amounts of belly cargo.

ECONOMICS AND FLEET PLANNING

Finally, on April 23rd, in its fleet plan, United Airlines announced that they would be phasing out all their B757 from the transatlantic routes and moving them onto the domestic market.

At the same time, they would use their B767 for these routes, eliminating the need for the occasional fuel stops and for other economic reasons. Could these types of fleet plans become the trend in the coming years? The question remains to be answered.

References www.bloomberg.com http://mashable.com/ http://www.wsj.com/ http://leehamnews.com http://www.prnewswire.com/ http://www.journal-aviation.com/ http://nl.flightaware.com/ NOAA

When coming to Europe, the inverse effect occurs. In days of high winds in the upper atmosphere, usually after a storm, speed records can be beaten. For example, last January flight BA114 made the trip from New York to London Heathrow in just five hours and fifteen

Airport operators in the Bangor MA, or Goose Bay, Canada fared much better, with boost to the local economy brought by these thirsty aircraft. Ultimately, airlines are not likely to increase the size of the aircraft they operate over the Atlantic, Most routes are too profit-thin to employ larger aircraft, and this problem only occurs in the winter months. Some airlines are

The future could bring some changes. The B757 is an ageing plane with no Boeing replacement planned or envisaged. The replacement is coming from Airbus with the recently unveiled A321LR. With its additional fuel tanks (and range), Airbus predicts (and hopes) this aircraft will entirely replace the B757 and dominate the transatlantic routes very much as the B757 did for the past two decades. However, with the current trend of global warming and a constantly increasing in jet stream, it is still to early to predict whether the A321LR will be able to bridge the deficiencies of the B757 or if global warming will put an end altogether to narrow-body Trans-Atlantic crossings.

Figure 1 - Comparison between a wavy polar vortex (left) and the normal configuration (right).

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WHY AERONAUTICS SHOULD HAVE A CLOSER LOOK AT LIQUEFIED NATURAL GAS

Meeting the future energy demands of aviation

Dr. Arvind Gangoli Rao, Associate Professor, Flight Performance and Propulsion At present around 3 billion passengers travel through air every year. With growing increase in GDP, the number of travellers is expected to increase to 7 billion by 2035 and 15 billion by 2050. Even though the crude oil prices are very low at the moment, with finite petroleum reserves available on our planet, it is expected that the jet fuel prices will increase in the future. Moreover, using kerosene as a fuel causes several emissions, which are bad for the environment. Liquefied Natural gas (LNG) can provide an attractive alternative for aviation.

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viation is the backbone of our modern society. At present, air transport contributes around 3-5% to anthropogenic causes of Global Warming. The air traffic is expected to grow at a rate of approximately 5% per year for the next couple of decades, implying that the number of aircraft will double every 15 years. As a result the environmental impact of aviation will increase significantly. Moreover, whereas surface transportation systems are able to reduce their CO2 and other emissions significantly, thanks to the increased use of electric/hybrid vehicles, the aviation sector is restricted in its energy source. The European Advisory Council for Aeronautical Research and innovation in Europe (ACARE), has set challenging goals for reducing the environmental impact of aviation. Targets for the year 2050 include a 75% reduction of CO2 emissions per passenger kilometer and a 90% reduction in NOx emissions. These targets are relative to the capabilities of typical new aircraft in 2000 [1].

One of the other main challenges for future aviation is the energy source. Currently, aviation consumes around 1.1 billion liters of jet fuel every day and it is anticipated this would increase by 3% every year despite the improvements in aircraft efficiency. On the other hand, the oil reserves are depleting, thus creating a discrepancy in the supply and demand, which will leads to an increase in the fuel costs. This increase in fuel costs has already increased the fuel share in the total operating cost of an airline to around 35% to 40% [2].

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Further increase in fuel prices would have disastrous consequences for airlines. Therefore, other means of releasing energy to drive the aircraft engines will have to be tapped.

Thus if aviation has to maintain its growth then the problem of energy source for aviation has to be solved first. Some analysts have high hopes on biofuels however there are serious problems with biofuel which include; scaling of production, fuel consistency, availability of biomass, conflict with the food chain, high price, competition with surface transport, un-

availability of subsidies in aviation, etc. Therefore, biofuel can be a part of the solution but not the solution itself.

There are several criteria in selecting a fuel for aviation. One of the main criteria is the energy density, as reducing weight and volume is of paramount importance for aviation. Both Specific Energy Density (SED, amount of energy per unit mass of the fuel) and Volumetric Energy Density (VED, amount of energy per unit volume) are important in this regard. Figure 2 shows several fuels/ energy sources in terms of their SED and VED [3]. It can be seen that Jet-A/kerosene has good SED and VED and therefore is suitable for aviation. It can also be seen that LH2 has high SED but a poor VED, implying that we would require huge volume to carry any reasonable amount of hydrogen.

The main advantage of carrying LH2 is that there is no CO2 emission from the combustion of fuel. The engine will emit water vapor

Figure 1 - Motivation of alternative fuels for aviation

mission (>10,000 km). The climate impact of such an aircraft was evaluated in detail and it was found to be substantially lower than a conventional aircraft. The operating cost is also lowered by 20-25% due to the lower cost of LNG [6].

For a Design Synthesis Exercise (DSE), a group of students at the TU Delft worked on the design of a Multi-Fuel A320 class of aircraft for short and medium range mission (shown in Figure 3). The results showed that the operating cost and emissions from the aircraft can be reduced substantially when compared to a conventional A320 aircraft. The operating costs were reduced by 10% due to lower emissions and cheaper fuel.

Figure 2 - Comparison of various energy sources for aviation and some amount of NOx as exhaust. Researchers have shown that there are several positive effects of using LH2 for aviation on the environment. At present, LH2 production is expensive and not environmentally friendly.

However, as society moves towards hydrogen based economy by utilizing renewable energy sources, the price of hydrogen is expected to reduce substantially. Hydrogen can be produced from renewable energy and is seen as a long-term fuel for aviation. But using LH2 in aviation has several challenges including large volume required for fuel storage, safety, logistics, passenger perception, etc. as investigated in the Cryoplane Project [4].

From Figure 2, it can also be seen that LNG is in between kerosene and LH2, both in terms of SED and VED. Currently LNG is one of the cheapest fuels available. The gas reserves of the world are enormous, especially with the discovery of shale gas, thus implying that LNG prices would be stable. LNG is one of the cleanest fuels and recently it has been proved that LNG can be generated by using renewable energy. Due to a higher energy density than kerosene, using LNG can reduce the amount of fuel that needs to be carried on board. Moreover, being a low carbon fuel, burning LNG or LH2 will reduce the CO2 emission significantly. Some of the advantages and disadvantages of using LNG is summarized below.

• • •

resulting in increased aircraft Operating Empty Weight (OEW).

Requires insulation to keep the fuel cool, increasing aircraft OEW further.

Increased storage space for LNG compared to conventional jet fuels.

Airport facilities and logistics for tanking LNG are required.

Using natural gas as a fuel is not a problem for the engine as natural gas is a clean fuel and can be burnt at a lower equivalence ratio.

This substantially reduces the NOx formation within the combustor when compared to kerosene. However, an additional heat exchanger has to be used for evaporating the LNG to natural gas. Since LNG is a cryogenic fuel and therefore a good heat sink, it can be used in a beneficial manner to enhance the thermodynamic efficiency of the engine for intercooling, bleed cooling, air-conditioning, etc. [5]. Using the cryogenic fuel for cooling the bleed air used for turbine cooling was found to be most beneficial with SFC reductions in the order of 6%.

A Multi-Fuel Blended Wing Body (MF-BWB) aircraft was designed in the AHEAD project.

The aircraft uses LNG and Biofuel as energy sources (shown in the main visual). The initial results are promising as the CO2 emission can be reduced by more than 50% when compared to B777-200ER for a long-range

LNG can offer several advantages as an alternative fuel for aviation; the logistical challenges and the high aircraft development cost are the main hindrances. However, as the society will demand lower emissions from aircraft in the future (with enforcement of the Emission Trading Scheme) and as the fuel will become more expensive in future, the breakeven point for switching over to a new fuel will become viable.

References [1] ACARE, 2011, Flightpath 2050 Europe’s vision for aviation, Technical Report, European Commission.

[2] IATA Economics, “IATA Economic Briefing”, February 2010.

[3] A. Gangoli Rao, F. Yin and J.P. van Buijtenen, “A Hybrid Engine Concept for Multi-fuel Blended Wing Body”, Aircraft Engineering and Aerospace Technology, Vol. 86 (6), Sept 2014.

[4] Slingerland, R., “Innovative Configurations and Advanced Concepts for Future Civil Aircraft”, VKI Lecture Series on Aircraft Design, June 2005.

[5] Van Dijk, I.P, Rao, G.A., and Van Buijtenen, J.P., “Stator Cooling and Hydrogen Based Cycle Improvements”, Int. Soc. of Air Breathing Engines 2009, Montreal Canada, ISABE 2009-1165.

[6] B. Cont, M.M. Doole, C.L.V. Driessen, M. Hoekstra, P.B. Jahn, K. Kaur, L. Klespe, C.H.J. Ng, E.M. Rezunenko, N.C.M. van Zon, “A320 Alternative Fuel Design the next generation sustainable A320 operating on Liquified Natural Gas for the year 2030”, TU Delft, 2014.

Advantages of LNG: • Lower fuel weight compared to kerosene.

• Approximately 25% reduction in CO2 emission.

• Approximately 60% reduction in NOxand particulate emissions.

• Usage of cryogenic heat sink can increase engine thermal efficiency.

• The LNG is substantially cheaper than conventional jet fuels.

Disadvantages of LNG: • Requires pressurized tanks for storage

Figure 3 - A Multi-Fuel A320 class of aircraft with podded LNG tanks and open rotors designed by a DSE group.

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ROB FAULKNER

WIND ENERGY

OPTIMIZING FOR FLUID-STRUCTURE INTERACTION

Design of aerodynamic bodies for optimal performance under unsteady conditions

Jaco Brandsen, PhD Candidate, Wind Energy Group and ASM Group, Dr. ir. Axelle Viré, Assistant Professor, Wind Energy Group, Dr. Sergio Turteltaub, Associate Professor, ASM Group, Prof.dr. Gerard van Bussel, Head of the Wind Energy Group, Faculty of Aerospace Engineering, TU Delft

TU Delft investigates innovative systems that exhibit behavior driven by fluid-structure interaction such as floating wind turbines, kite power systems, and solar vehicles. Each of these systems are still in the initial stages of commercialization meaning that the optimal design for each system has yet to be found. The goal of the present research project is to use transient shape optimization techniques to determine optimal designs for cutting-edge aerodynamic components or systems such as these.

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luid-structure interaction (FSI) can be characterised as a situation in which a deformable structure interacts with a fluid that is flowing externally or internally to it. An example of an aerodynamic system that has been optimized for FSI is the rotor of a horizontal-axis wind turbine. The aerodynamic forces exerted by the wind on the rotor cause the blades to bend toward the tower of the turbine. This bending may result in each blade deforming into a shape that is aerodynamically inferior to the shape it was designed to have during operation, thereby detrimentally affecting the power generated by the wind turbine.

Furthermore, the bending of the blades creates the hazard that the blade tips may strike the tower when the rotor is turning. These issues are often addressed by designing each blade to have a pre-bent shape which shapes that curves away from the tower when there is no wind. Consequently, the aerodynamic forces will then deform the blade, from its 78

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pre-bent shape, into the aerodynamically favourable shape that it is should have during operation. This increases the power harvested by the rotor from the wind and therefore also enhances the performance of the wind turbine. Pre-bending the blades also enlarges the clearance between the blade tips and the tower thereby mitigating the hazard of the tips hitting the tower.

OPTIMAL DESIGN FOR TRANSIENT CONDITIONS Many components or systems, which exist within engineering have to operate under conditions, which are continuously varying with time, also referred to as transient or unsteady conditions. Take the system illustrated in Figure 1, for example, which consists of a rigid airfoil attached to a linear spring and a torsional spring. A system such as this could be used as a simple model for an aerodynamic body such as an aircraft wing or a wind turbine

blade. For the purposes of this discussion, it will be assumed that the system in Figure 1 is a model of a wind turbine blade, with the rigid airfoil representing the blade profile. The linear spring and the torsional spring represent the bending stiffness and the torsional stiffness of the blade, respectively. The variable U(t) denotes the wind which is constantly changing as time, t, passes. As a result, the angle of attack, α(t), at which the aerofoil profile of the blade is operating, is also constantly changing with time.

Consider the hypothetical design problem of specifying a shape for the aierofoil profile of the wind turbine blade so that the blade will perform optimally with respect to a specific design criterion. Furthermore, let the performance of the blade with respect to this design criterion depend on the angle of attack at which the aierofoil profile is functioning. The design criterion could be a quantity such as lift, drag, power extracted from the wind, etc. A traditional approach when designing a system or component is to identify one or more specific design load cases that may arise during operation. Suppose that this approach is applied to the system in Figure 1 and that a set of design load cases, such as the set illustrated in Figure 2, is derived. The three design load cases in

id-body dynamics solver which will be written in the programming language, Python. The rigid-body dynamics model will describe the geometry of the structure using special mathematical equations known as non-uniform rational basis splines (NURBS). NURBS are commonly utilized in computer-aided design (CAD) software packages because they are able to accurately represent a wide variety of complex shapes.

Figure 1 - System consisting of a rigid airfoil attached to a linear spring and a torsional spring. This system may be used as a simple model for a flexible aerodynamic body such as a wind turbine blade.

Figure 2 correspond to the mean, minimum and maximum angles of attack, denoted as αmean, αmin and αmax, respectively, at which the airfoil profile of the blade will have to operate.

Finally, also assume that most of the time the airfoil profile is functioning at the mean angle of attack, αmean.

One possible strategy is to design the airfoil profile so that it will perform optimally at the most common angle of attack, αmean, and at least adequately at the extreme angle of attack values of αmin and αmax. Alternatively, a second possible strategy is to design the airfoil so that the system performs well at all three of the angles of attack, α_mean, α_min and αmax. However, the performance of the system will then likely not be optimal at any one of the three design load cases in particular, but will instead be an optimal compromise between the design load cases. Both of these design strategies rely on the premise that in order for the system to perform optimally, it only has to be able to deal with each of the design load cases. In addition, in both strategies each design load case is treated as an individual set of conditions under which the system will have to operate. This set of conditions is regarded as being completely independent from the sets of conditions represented by the rest of the design load cases.

The design strategies described in the previous paragraph are both somewhat unrealistic.

In reality, the system will only operate under a single set of transient conditions and the design load cases in Figure 2 are simply discrete values that this single set of conditions will have at certain specific moments in time.

Consequently, evaluating only the sets of conditions corresponding to the design load cases, when designing the system, disregards the transition period during which the conditions are changing from the one design load case to the next. The present research project will therefore focus on optimizing the performance of an aerodynamic system or component directly with respect to the transient conditions under which it will have to function.

DEVELOPMENT OF A FSI SIMULATION SOFTWARE TOOL Before performing a FSI simulation of the behaviour of an aerodynamic body, a fluid dynamics computer model must first be developed to represent the flow of the fluid past the body. A structural dynamics computer model also needs to be constructed which represents the structural properties of the aerodynamic body. The open-source, computational fluid dynamics (CFD) solver, Fluidity, was selected for the setting up of the model of the fluid flow past the body. The structural dynamics model will be set up using a rig-

A FSI simulation software tool, shown schematically in Figure 3, will be formed by coupling fluidity to the rigid-body dynamics solver.

Practically, the term “coupled” means that data will be exchanged between the two solvers.

During an FSI simulation of an aerodynamic body, the motion of the body will be predicted for a finite period of time. This period of time is divided into a number of discrete segments known as time steps. During each time step, the aerodynamic forces exerted on the body by the fluid are transferred from the CFD model to the rigid-body dynamics model. The new position and orientation of the body is also transferred from the rigid-body dynamics model to the CFD model.

Fluidity allows the immersed body method to be employed by the FSI simulation software tool (Viré et al, 2012). A CFD solver is capable of obtaining the flow pattern of the fluid at a finite number of points in space. The locations of the points are defined using a mesh.

A characteristic feature of the immersed-body method is that the aerodynamic body, which is being analyzed, is superimposed on the mesh of the CFD model so that the mesh of the CFD model passes through the body. An advantage of the immersed-body method is therefore that the mesh of the CFD model does not have to conform to the shape of the aerodynamic body. A solid concentration field (indicated by the red region on the mesh of the CFD model in Figure 3) tracks the location and orientation of the body on the mesh of the CFD model.

TRANSIENT SHAPE OPTIMISATIONOPTIMIZATION OF AERODYNAMIC BODIES Once completed, the FSI simulation software tool will be integrated with a transient, gradient-based, optimization algorithm (Turteltaub,

Figure 2 - Possible design load cases that may be selected for the design of the wind turbine blade. The load cases correspond to the mean, minimum and maximum angles of attack at which the airfoil profile will operate.

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2005) to create a FSI design optimizsation tool that will determine the optimal shape for an aerodynamic body operating under unsteady conditions. The FSI design optimizsation tool will be used to improve the shape of technology-relevant aerodynamic bodies, which are commonly encountered in engineering. The optimal shape of the aerodynamic body is the geometrical shape that the body should have in order for it to perform optimally with respect to a certain design criterion. As already mentioned, the criterion could be a property such as drag, lift, efficiency, power output, etc. A flow chart of the basic scheme that which will be employed by the FSI design optimization tool is provided in Figure 4. The performance of the aerodynamic body is measured using the variable L which corresponds to the criterion with respect to which the body is being optimised. The value of L depends on the shape of the aerodynamic body, s. The optimal shape of the aerodynamic body is the shape, s, which minimises the value of L. In order to calculate the optimal shape for the aerodynamic body an initial guess for the optimal shape is first made. A FSI simulation is then performed, using Fluidity and the rigid-body dynamics code, of an aerodynamic body which has the initialbody that has the initial guess shape. The values of L and a second quantity known as the shape sensitivity, (∂L/∂s), are then calculated by the transient, gradient-based, shape optimisation algorithm from the results of the FSI simulation.

The shape sensitivity indicates how s should

Figure 3 - Schematic representation of the FSI simulation software tool which will be formed by coupling Fluidity to the rigid-body dynamics code. be changed in order to further decrease the value of L. In other words, the shape sensitivity states how the shape of the aerodynamic body must be modified in order to further improve its performance. Based on the value of the shape sensitivity, an incremental change is made to s thereby yielding a new shape for the body. A FSI simulation is then conducted of an aerodynamic body with the new shape after which new values are computed for L and (∂L/∂s). This, in turn, leads to a new body shape, s, which will further decrease the value of L and improve performance. This process

is iteratively repeated until a value of zero, or almost zero, is obtained for (∂L/∂s). A shape sensitivity, which is equal to zero, or almost zero, indicates that making further changes to the shape of the body will not yield a (significant) reduction in the value of L nor an enhancement of performance. The value of s obtained from the latest iteration is then the optimal shape for the aerodynamic body.

CONCLUSIONS Systems or components, which have to operate under unsteady conditions and display behavior driven by FSI are encountered throughout engineering. Floating wind turbines, kite power systems, and solar vehicles have already been mentioned as innovative examples of such systems that are currently being investigated at TU Delft. Furthermore, the commercialization of each of these systems is still in the initial stages, which means that the optimal design for each system has yet to be determined. The aim of the research project, described in this article, is to contribute to the solution of this problem by applying transient shape optimization methods to the design of these and other ground-breaking engineering systems.

The research project covered in this article is funded by the Faculty of Aerospace Engineering through the Cross FertilisationFertilisation Research Incentive Scheme (XFRIS).

References

Figure 4 - Basic scheme that will be employed by the FSI design optimization tool.

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[1] A. Viré, J. Xiang, F. Milthaler, P. E. Farrell, M. D. Piggott, J.-P. Latham, D. Pavlidis and C. C. Pain, “Modelling of fluid-solid interactions using an adaptive-mesh fluid model coupled with a combined finite-discrete element model,” Ocean Dynamics, vol. 62, pp. 1487-1501, 2012.

[2] S. Turteltaub, “Optimal non-homogenous composites for dynamic loading,” Structural and Multidisciplinary Optimization, vol. 30, no.

2, pp. 101-112, 2005.

SOS-CATASTROPHES.EU

COLUMN

SUICIDAL PILOT AT THE HELM

Aftermath of the Germanwings crash

Lubi Spranger, MSc Student Aerospace Engineering & Editor, Leonardo Times When the Germanwings flight 9525 crashed in the French Alps in March, nobody initially suspected that it was a deliberate crash caused by the co-pilot Andreas Lubitz. He locked himself inside the cockpit; initiating a steep descent in midcruise. How often do pilot suicides happen and how can they be prevented?

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as during the 2009 Air France Flight 447 crash into the Atlantic Ocean where the air speed indicator gave faulty measurements. Another incident occurred in November 2014, when two of the three angle of attack (AoA) sensors froze on a Lufthansa A321, the slightly larger version of the A320. As a consequence, the autopilot lowered the nose and entered a steep descent of 4000fpm, which is more than twice the normal rate of descent for this

Whilst technical problems in airplanes can lead to serious incidents and accidents, in most of the rare occurrences of technical errors, corrective actions by the pilots prevent a serious accident to happen. In the case of a steep descent initiated by a suicidal pilot on REUTERS

irectly after the loss of the Germanwings aircraft, there were numerous speculations about the cause of the crash.

Could a technical error have led to the loss of 150 lives? This seemed highly unlikely considering the good safety record of the A320, with only 0.14 fatal accidents per million takeoffs [1]. Despite the high safety of this passenger aircraft, there have been several technical problems regarding aircraft instruments, such

aircraft [2]. The crew was able to safely land the aircraft and as a consequence, the European Aviation Safety Agency (EASA) required the flight crew manuals to be amended so that in the event of two inoperative AoA sensors, only one Air Data Reference Unit would be kept activated. The probability of a recurrence is being investigated [3].

Germanwings A320 flight 9525, before its departure from Barcelona.

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AFP

purpose, things are different.

SIMILAR INCIDENTS The crash in the French Alps was not the first ever pilot suicide recorded in the past; a research article analyzing aircraft-assisted suicide in the US over a period of 21 years indicated that 37 pilots committed or attempted suicide, between 1983 and 2003. Of these, 36 cases resulted in at least one fatality and all cases were general aviation flights with a male pilot [4].

Similar cases outside the US include the SilkAir Boeing 737 crash in Indonesia with all 104 people on board killed in 1997. Although the Indonesian authorities did not officially designate the crash as suicide-caused, US investigators concluded from their research that the financially and family-troubled pilot deliberately crashed the plane. The EgyptAir Boeing 767 crash into the Atlantic Ocean in 1999 is another example: the steep dive of the jet plane appeared to have been initiated by the co-pilot on purpose, in spite of not being deemed as such by American investigators under the pressure of Egyptian officials. In the same year, an Air Botswana turboprop was hijacked by one of the airline’s pilots and steered into two passenger planes on the ground, destroying the entire operational fleet of the airline at the time and killing the pilot [5].

There are also speculations about Malaysia Airlines Flight MH370 last year possibly having been purposely caused by the pilot and there are several other examples of plane crash attempts with the same motif. One example is a JetBlue flight in 2012, where the captain diverted the flight to take a “leap of faith” and the co-pilot together with an off-duty pilot had to overpower the pilot, to gain back control.

The exact number of (attempts of) deliberate plane crashes by pilots remains unknown, since in many cases, the local authorities reject pilot suicide as the official cause of the crash, as demonstrated by the Indonesian and Egyptian airline crashes.

COCKPIT REGULATIONS The US Federal Aviation Authority (FAA) set a requirement for US airlines, which dictates that when a pilot exits the flight deck, another qualified crew member must stay in the cockpit and lock the door until the return of the pilot.

In Europe, the regulations are different. Before the crash of the Germanwings flight EASA only had the rule set in place that at least one pilot had to be at the controls of the aircraft at all times during flight. This rule made it possible for the co-pilot Andreas Lubitz to be alone on the flight deck, lock the door and crash the aircraft into the French Alps [6]. Shortly after the Germanwings crash, EASA published a new recommendation for national aviation authorities and commercial air transport operators operated with more than one cabin crew, requiring the presence of at least two authorized persons to be in the flight crew compartment at all times [7].

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A rescue worker inspecting the crash site of Germanwings A320 flight 9525.

This “rule of two” probably does not eliminate the chance of a pilot committing suicide altogether, since the pilot could also subdue the second crew member inside the cockpit behind locked doors, but it significantly lowers the chance. Recent studies have shown that despite the general conception that adolescent suicide is impulsive in the moment, it is generally not an impulsive act, but rather the result of extensive planning [8]. However, when having another person in the cockpit, a suicidal pilot would have to plan a lot more carefully, since the reaction of the other person can never be anticipated completely and makes for a more risky plan.

SCREENING OF PILOTS US Pilots are required to pass a medical exam every year by the FAA when less than forty years old and semi-annually for those older than forty. EASA uses a similar psychological assessment which, however, does not include a formal mental health evaluation. This medical exam can be carried out by doctors who are not trained in mental health. It focuses on physical health and includes yes-or-no questions about a pilot’s mental health [6].

Disclosing mental health problems or the usage of anti-depressants can be risky for pilots, since that could take them off the flight schedule. It is very hard to judge whether a pilot has suicidal thoughts even as a professional psychiatrist, since pilots themselves are trained professionals when it comes to walling off high levels of stress or emotional difficulties to not let them interfere with their task as pilot. Hiding depression and suicidal thoughts during rudimentary psychological assessments should therefore not be too difficult either. But then, how could one possibly filter out a pilot with the plan to commit “aircraft-assisted” murder-suicide? Does a screening procedure exist whereby the risk of having a suicidal pilot in the cockpit can be ruled out

completely? Probably not.

But the screening procedures could be modified to include a more thorough psychological assessment with better assurances of being able to keep one’s job as pilot and having the chance to own up to possible mental problems. The fear of lost respect by one’s family and society in the role as pilot and job security should not stop a troubled pilot from telling the truth and finding a way to deal with mental health problems. Airlines should make psychological support schemes available and openly integrate suicide prohibition into trainings to show pilots, who might be depressed with similar thoughts that they will receive support.

The safety rankings of airlines with an active “suicide prevention” should be set higher compared to airlines without a similar policy, both beneficial for airlines and passengers.

Even though only about 2.5% of all suicides are homicide-suicides and only about 1% of all plane crashes from 1993 to 2012 were caused by suicidal pilots, there is still room for making aviation even safer [9][10].

References [1] firstpost.com [2] krepelka.com [3] avherald.com [4] C.B Bills, J.G. Grabowski, G.Li,“ Suicide by Aircraft: A Comparative Analysis”, Aviation, Space, and Environmental Medicine Vol. 76, No. 8, August 2005 [5] nytimes.com [6] theguardian.com [7] EASA Safety Information Bulletin SIB No.: 2015-04 [8] ncbi.nlm.nih.gov [9] nbcnews.com [10] time.com

Global environmental concerns call for future innovative products. Currently, the aircraft industry is seriously considering to install Contra-Rotating-Open-Rotors (CROR) on mid-range 150-200 seater aircraft by the year 2020. Today, NLR (National Aerospace Laboratory) specialists work in close coรถperation with aircraft & engine manufactures to investigate noise, vibration and safety aspects of these novel aircraft concepts.

www.nlr.nl

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