October 2016

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

1996

2016

BOEING 100 YEARS DSE

Occupy Mars

Carbon flying

Summer 2016

SpaceX or NASA

Our climate impact

Page 31 Year 20 | N°4 | October 2016

Page 16

Page 42

KLM ROYAL DUTCH AIRLINES

Biofuel. You won’t notice the difference, but nature will KLM has proven that aviation can be more sustainable. As a pioneer we operated the world’s first commercial flight with biofuel. However, KLM will only use biofuels with no negative effects on food production and nature. Together with partners we stimulate the development of biofuel, only when used on a large scale biofuel will make the difference - klmtakescare.com

EDITORIAL Dear reader, Landing on another planet is no small feat.

After forty years of blasting probes to Mars, we have apparently not yet mastered the art of touching down on our red neighbor.

Despite our many attempts, less than 50% of all missions were successful. Some failures were just bad luck - others very preventable.

We are never anxious or upset, however, about these failures because they are merely machines that failed to send back a signal.

But what if some day, humans would be the ones not to call home?

This idea is becoming less and less fictive as plans for manned Mars missions are becoming a prospect of the next decade and not century. At least according to SpaceX and MarsOne, humanity will become an interplanetary species within the next ten years.

In a TED-like speech, Elon Musk presented SpaceX’s concrete Mars architecture for this very purpose. For him, the first human will just be one of many colonizers, who will have to stay for a while with little chance of return.

NASA on the other hand, plans to send a man to Mars in 2030 and Boeing CEO, Dennis Muilenburg, said the first man on Mars would arrive aboard a Boeing rocket (for more, see page 16). MarsOne is also planning to be the first, though virtually no technology backs its claims. Now, who will be the first ones to venture out to the desolate carmine planet, what do you think?

I think it is fascinating to see how we are entering a modern race to space – or to Mars this time – and I am eager to see the outcome. Going to another planet appears to be the way to evade “dooms day” according to Musk.

Yet we should not lose focus of our terrestrial problems, like climate change or the growing economic inequality. You might think of it as homage when someone offers a ticket to another planet for those who can afford it, so mankind can venture out into the stars.

Last edition ...

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

1996

2016

ECO-RUNNER

Luckily others are doing their best to offer us a sustainable future on Earth.

Musk’s other commitment for instance, Tesla, is attempting to slowly but steadily cut big oil out of the automobile business.

For airplanes, Bertrand Piccard and André Borschberg demonstrated that there are alternatives to kerosene and power generation might have a future in fusion as the Wendelstein 7-X has shown. Scientifically, 2016 was a successful year.

Politically it might still become a disaster for innovation and the future of this planet. Believe it or not, a climate change denier might be elected president of the United States by the time you read this. Donald Trump believes climate change is made up to make the U.S. economy less competitive. While this would disqualify you to run for anything in Europe, he is just the loudest exponent of a large group of people overseas.

Needless to say, I believe climate change is real but maybe not everything about it is horrible. Generally, the need for change sparks innovation, and through innovation in technology we can make it possible both to go to Mars and stay here, we just have to keep on trying.

And perhaps the innovation will lead us to a way to land safely on Mars.

Victor Gutgesell Editor-in-Chief

Emirates’ A380s

G-Waves

Interview Matt Taylor

Big airline, big planes

Einstein was right

About Rosetta and his career

Page 12

Page 17

Page 44

Year 20 | N°3 | July 2016

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

LT www.leonardotimes.com

Likes us on Facebook /leonardotimesjournal

LEONARDO TIMES N°4 2016

03

CONTENTS FRONT FEATURES 03 Editorial 07 Leonardo's Desk 08 In the News

12

Aerodynamics in F1 An experience of a one-year internship at the Aero Department of the Mercedes AMG Petronas Formula One Team, designing and testing around the whole development cycle, from CAD to track.

SPACE DEPARTMENT 10 Juno Mission

AERODYNAMICS 12 Aerodynamics in F1 20 The Tractor-Trailer Gap

NICK'S CORNER 16 Occupy Mars

SPACE ENGINEERING 17 Linear Stability of Periodic Lagrange Orbits in the ER3BP

23 Boeing 100 Years On July 15 2016, Boeing turned 100 years old. It’s therefore high time to dive into the history and triumphs of this incredible company.

FLIGHT PERFORMANCE AND PROPULSION (FPP) 18 Nuclear Propulsion with Thorium 42 Carbon Flying

TIME FLIES 23 Boeing 100 Years

AVIATION DEPARTMENT 28 Solar Impulse 2

DESIGN SYNTHESIS EXERCISE 32 ARMADA 32 SAGA 33 AEOLUS 34 HERIADES 35 Starling 9000 35 HORUS 36 PICS 37 MATRYOSHKA 37 ICARUS+ 38 Magnus Aeolus 39 MIRU

INTERNSHIP 40 Internship at Volvo Car Corporation

Design Synthesis Exercise

ADVERTISMENTS 02 KLM 06 ASML 50 ASML Editorial 51 NLR 52 Fokker

04

N°4 2016 LEONARDO TIMES

31

Solar Impulse 2 Solar Impulse was an initiative of the Swiss engineer André Borschberg and the Swiss aeronaut Betrand Piccard.

Their goal was to build an aircraft that only relies on solar power and to give the world an example of what already can be achieved with clean energy technologies.

SOLAR IMPULSE

COLOPHON

28

Year 20, NUMBER 4, October 2016 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 four times a year with a circulation of around 5000 copies per issue.

EDITOR-IN-CHIEF: Victor Gutgesell FINAL EDITOR: Nicolas Ruitenbeek EDITORIAL STAFF: Mannat Kaur, Martina Stavreva, Nicolas Ruitenbeek, Nithin Kodali Rao and Thijs Gritter.

BRANDON FARRIS

FINAL WEB EDITOR: Rosalie van Casteren THE FOLLOWING PEOPLE CONTRIBUTED: Casper Dek, Jasper ten Bloemendal, Lotfi Massarweh, William Mulkens, Daniele Giaquinta, Thrilok Kummetha, Robert Regtuit and Jelle Westenberger.

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. The views expressed do not necessarily represent the views of the Leonardo Times or the VSV 'Leonardo da Vinci'.

VSV ‘Leonardo da Vinci’ Kluyverweg 1, 2629HS Delft Phone: 015-278 32 22 Email: VSV@tudelft.nl

Lagrange Orbits

ISSN (PRINT) : 2352-7021 ISSN (ONLINE): 2352- 703X

The Restricted 3-Body Problem (R3BP) represents a model useful to accurately describe the motion of a small spacecraft under the gravitational attraction of two large masses, which are revolving in an unperturbed Kepler orbit.

Visit our website www.leonardotimes.com for more content. Remarks, questions and/ or suggestions can be emailed to the Editor-in-Chief at the following address: LeoTimes-VSV@student.tudelft.nl

46 LEONARDO TIMES N°4 2016

05

How do you make a lithography system that goes to the limit of what is physically possible?

At ASML we bring together the most creative minds in science and technology to develop lithography machines that are key to producing cheaper, faster, more energy-efficient microchips. Our machines need to image billions of structures in a few seconds with an accuracy of a few silicon atoms.

So if you’re a team player who enjoys the company of brilliant minds, who is passionate about solving complex technological problems, you’ll find working at ASML a highly rewarding experience. Per employee we’re one of Europe’s largest private investors in R&D, giving you the freedom to experiment and a culture that will let you get things done.

Join ASML’s expanding multidisciplinary teams and help us to continue pushing the boundaries of what’s possible.

www.asml.com/careers

/ASML

@ASMLcompany

LEONARDO'S DESK

A MESSAGE FROM THE NEW BOARD Dear reader, While writing my first preface for the Leonardo Times, I have realized how much effort is involved in writing a scientific journal.

The fact that a group of students is capable of producing a high quality magazine with technical articles and in-depth interviews inspires me and makes me enjoy reading it even more.

Since the last edition of the Leonardo Times, there have been a lot of developments in our profession, of which I would like to highlight one in particular. On the 26th of July, a solar-powered aircraft has circumnavigated the globe for the first time. This journey took about sixteen months to complete due to battery damage, but the Solar Impulse 2 proved that it is possible to fly a solar-powered aircraft day and night over long distances. With motors that deliver about the same amount of horsepower as the Wright Flyer I, it shows us that there is a lot of need for improvement in the years to come. We have been flying with fossil-fuel powered engines for over 100 years and if we would like to change our way of flying, the first steps should be taken right now, regardless of which form of energy will be used.

Back to the VSV; during the past months, the introduction activities were organized.

We taught our new students all the “ins” and

“outs” of our society during the Freshmen Weekend, which was held at Woensdrecht Airbase. Here we also saw some amazing displays, amongst which was a NH-90 helicopter. Furthermore, a Faculty Sneak Preview was organized for the international students to show them around some of the facilities our faculty has to offer, such as the Clean Room and our SIMONA flight simulator. With the ever increasing amount of international students at our faculty we think it is very important to integrate them in our student community to learn from each other.

Currently, the newly installed board, departments and committees are preparing the activities for the upcoming year. The Aviation Department is working on the theme of our annual symposium, which will be organized in March 2017. With a history of organizing symposia for more than 60 years, this group of 3rd and 4th year students has to live up to the high standards that the VSV ‘Leonardo da Vinci’ sets itself for this symposium. In the meantime, the Space Department is organizing a big network event called ‘Discover your Space’ in cooperation with the Netherlands Space Society (NVR). After a successful first edition last year, this event will be held in November. Furthermore, they will organize this year’s multiple-day-excursion in July to visit aerospace related companies abroad.

Our Master Department ‘Apollo’ will organize a Case Tour next summer, in which the

students will work on challenging cases at companies from different branches. Along with this big trip, they will be organizing a lot of career oriented workshops and company visits throughout the year.

The largest tour the VSV organizes every year is the study tour. The last study tour was organized to Brazil and Chile, and it included visits to companies such as Helibras, Embraer and the Very Large Telescopes in Antofagasta. Even though this group of students and professors has not yet returned to Delft, the new committee is already searching for the best destinations in and around Europe for the next Study-tour, which is planned for September next year.

With all these activities planned for the upcoming year, I am sure we will be able to inspire the aerospace engineers of the future to make the most out of their studies and become active in the aerospace sector.

I hope you will enjoy reading this edition of the Leonardo Times as much as we do.

With winged regards, Casper Dek President of the 72nd board of the VSV ‘Leonardo da Vinci’

LEONARDO TIMES N°4 2016

07

QUARTERLY HIGHLIGHTS "Farewell Rosetta, you’ve done the job" “That was pure science at its best” said Patrick Martin, Rosetta mission manager, as the twelve-and-a-half-year long mission concluded its operations on September 30, 2016. Being one of the most significant endeavors of the European Space Agency, the Rosetta mission holds the title for several ‘scientific firsts’. The very final signal from the Rosetta probe brought with it an emotional farewell. “I don’t know what to say but I’ll say something… Rosetta was rock and roll.

It turned everything up to eleven.” remarked Matt Taylor, Rosetta project scientist.

Launched in March 2004, the Rosetta spacecraft consisted of the Rosetta probe featuring twelve instruments and the Philae lander. After travelling for over ten years and covering up to 6.4 billion kilometers, the spacecraft arrived at Churyumov-Gerasimenko, also known as Comet 67P, in August 2014. The objective of the Rosetta mission was to study the origin of comets by not only a rendezvous with the comet, but by also entering orbit around it. Further, in November 2014, the Philae lander detached from Rosetta and landed successfully, although oddly in the shadow of a cliff, on Comet 67P. This was the first time such an extraordinary feat, to land on a comet, was accomplished.

However, Philae’s odd landing caused the lander to be unable to collect enough solar power and hence unable to function as

hoped or transmit much data in the first two days itself..

Despite this bump in the road, the legendary mission has been quite the success. The Rosetta mission has taught us many things about Comet 67P, and perhaps even the Solar System. 67P is thought to be so oddly-shaped, as it is believed to have started out as two independent bodies that collided and fused and at some point in the past. The density of the comet is measured to be less than Styrofoam but its surface is extremely hard. Water vapor has also been detected on the comet, but its configuration is unlike the water vapor found on Earth, making it an unlikely candidate to have hydrated our blue planet. However, scientists have also

found glycine and other organic molecules that might have been its precursors. In a way, this is a direct access to the simple ingredients that might have eventually kick-started life. Just like the Rosetta mission, comets are truly one of a kind. They are primeval cosmic objects formed over 4.6 billion years ago when our solar system was beginning to take shape. Studying the details of such comets can help us to not only understand the evolution of our solar system, but also how our home planet might have been impregnated. The coming years will shed light on many questions as the immense amount of data and images collected from this mission are analyzed. Though surely, as a mark of good science, we will have more questions than answers.

directly funded, amounting to around 2% of the annual revenues for the aviation sector.

Many countries, including the two largest contributors of the greenhouse gases; USA & China, have promised to begin this scheme in 2020, even though it is voluntary until 2027. Under this offsetting scheme, the aim is to reduce the global aviation emissions by 80% (relative to 2020) until 2035.

This agreement is a milestone as it is the world’s first accord to control greenhouse gas pollution in aviation. The deal is not perfect and has already been undermined by environmentalists. However, it is truism that this deal marks the beginning of a new chapter in the history of international civil aviation, by calling for sustainability as a way of flying.

Our carbon footprints The demand for air travel has been on the rise constantly over the past few decades.

Being one the safest, fastest and comfortable means of transportation, the aviation industry foresees that this trend will continue in the years to come. Even though automobiles produce higher emissions and aircraft are now much more fuel efficient than before, the recent bloom in the air travel industry has ensured an increase in the amount of pollution attributable to international commercial aviation.

In a historic agreement between the government, the industry and the civil society representatives in Montreal this October, the Plenary Session of the United Nations aviation agency’s 30th Assembly agreed on a new global market-based measure (GMBM) to mitigate international aviation emissions.

The UN aviation agency, International Civil Aviation Organization (ICAO), finalized an agreement with its 191 member states to address over a thousand tons of greenhouse gases emitted annually by passenger and cargo flights. Under the agreement, forestry and other carbon-reducing activities will be 08

N°4 2016 LEONARDO TIMES

When space science meets civil engineering When it comes to telescopes, the bigger it is, the better. China has recently completed the world’s largest single-aperture radio telescope, having a diameter of 500 meters or roughly thirty football fields. The Five-hundred-meter Aperture Spherical Telescope, or simply ‘FAST’, contains a giant dish made of 4,450 panels. Resting in a natural basin within the hilly Guizhou Province in southwestern China, this megastructure requires a 5-kilometer radius of radio silence. This has led to the relocation of over 9,000 people from the surrounding villages. Although not operational yet, the last panel was placed in July this year and marked the end of the construction phase. FAST’s gigantic dish will scan the cosmos for radio emissions from stars and galaxies, probe gravitational waves, catalog pulsars and even look for signs of intelligent life. This telescope is foreseen to have a significant impact on modern astronomy and natural sciences.

The previous holder of the title of the world’s largest telescope was the Arecibo Observatory in Puerto Rico, having a 300-meter-wide dish. Although only 200 meters more in diameter, FAST has a collecting area that is more than twice that of the Arecibo Observatory, as it is significantly deeper, making it twice as sensitive. In addition to this, FAST has a unique feature that at a single moment,

it uses only a 300-meter-wide circle turned into a ‘parabola’ to focus cosmic (radio) waves on the receivers. This parabolic section can be shifted in real time to compensate for the Earth’s rotation as well. This parabolic section can be moved around within the 500-meter-wide dish and this is the very first time such a feature has been implemented. As for the range of motion, FAST has the ability to point anywhere within ±40° from the zenith while Arecibo is limited to a ±20° sway from the zenith. FAST’s working range of frequency has a lower limit of 70 MHz and

an upper limit of 3.0 GHz, which has been set depending on the precision with which the primary reflectors can approximate a parabola.

Currently undergoing various stages of testing and commissioning, FAST will be ready for operations in three years. However, it isn’t foreseen to operate at full capacity for several years to come due to a lack of astronomers.

If the cosmos is your calling, then this might just be the perfect time to head to China.

LEONARDO TIMES N°4 2016

09

JUNO

A detailed look at the satellite that is currently orbiting Jupiter SPACE DEPARTMENT

Jasper ten Bloemendal, BSc Student Aerospace Engineering, TU Delft

‘In Greek and Roman mythology, Jupiter drew a veil of clouds around himself to hide his mischief. It was Jupiter's wife, the goddess Juno, who was able to peer through the clouds and reveal Jupiter's true nature. The Juno spacecraft will also look beneath the clouds to see what the planet is up to, not seeking signs of misbehavior, but helping us to understand the planet's structure and history.’ – NASA

N

early five billion years ago, a star in our galaxy exploded. The explosion caused a nearby cloud of gas and dust to collapse and flatten into a spinning disk. Most of the gas and dust collected into a hot and dense core, which became our sun. The remaining debris formed the planets and other small bodies in our solar system. The majority of that debris came together to form the giant planet, Jupiter. Of all eight planets, it is believed that Jupiter was formed first. Because of its enormous size and powerful gravity, it is also believed that Jupiter influenced the formation and evolution of the other bodies that orbit our sun. Unlike these 10

N°4 2016 LEONARDO TIMES

other bodies, the composition of Jupiter has remained unchanged since the formation of the solar system. Therefore, similar to a time capsule, Jupiter can help reconstruct nearly five billion years of history. [2]

THE MISSION The Juno mission is the second spacecraft designed under NASA’s New Frontiers Program. It succeeds the Pluto New Horizons mission, which gave us a first close-up look at the dwarf planet. In July 2015, mankind received the first pictures from the spacecraft after a nine-and-a-half year flight, setting the bar for the Juno mission.

New Frontiers was a program NASA created in 2003 for medium-sized missions with a limit of one billion dollars in development and launch costs each. As a reference, the Curiosity rover cost about $2.5 billion. A third mission is expected to begin selection in November 2017, aiming to launch in 2024.

In 2003 the National Research Council identified the design of a Jupiter orbiter as a scientific priority, given how little is known about this giant. Underneath its dense cloud cover, Jupiter holds the secrets to the fundamental processes and conditions that formed our solar system the way we know it today. As the perfect example of a giant gas planet, Jupiter can also provide valuable knowledge for understanding the planetary systems that are being discovered around other stars.

Based on these principles, the Juno mission

was brought to life and assigned the following mission goals. Juno will: • Determine how much water is in Jupiter's atmosphere, which helps determine which of the proposed planet formation theory is correct (or if new theories are needed).

• Look deep into Jupiter's atmosphere to measure its composition, temperature, cloud motions and other properties.

• Map Jupiter's magnetic and gravity fields, revealing the planet's deep inner structure - is its core solid or not?

• Explore and study Jupiter's magnetosphere near the planet's poles, especially the auroras – Jupiter's northern and southern lights – providing new insights on how the planet's enormous magnetic force field affects its atmosphere.

With these goals in mind, Juno was originally planned to launch in June 2009. Due to budgetary restrictions, the launch was delayed until August 5, 2011. On July 4 of this year, the spacecraft entered orbit around Jupiter.

At the time of writing this article, it is completing its first orbit around the gas giant. Over the next eighteen to twenty months, thirty-seven more orbits will follow. This means that a deorbit into Jupiter's atmosphere is scheduled for February 2018.

hydrogen and helium. Jupiter however also contains heavier elements that form the building blocks of rocky planets such as Earth and Mars. This means that something happened between when the sun formed and the time Jupiter molded. Revealing the exact composition of Jupiter and its structure underneath its clouds might help in understanding what happened. This process is very important for the creation of planets and eventually, life.

Juno will also be mapping the extreme magnetic and gravity fields around Jupiter. Due to its extreme magnetic fields, Jupiter also houses the strongest auroral emissions in the entire solar system. This phenomenon is also known here on Earth as the northern and southern lights. Because of Juno’s polar orbit, the spacecraft will fly right over the phenomenon and be able to do a proper investigation. Comparing these results with the auroras of Saturn and Earth will give a better understanding of auroras in general. [3]

THE SPACECRAFT

Revealing whether or not Jupiter has a rocky core will be the key to understanding how and when the giant planet formed. If Juno reveals a solid core, it implies that Jupiter formed after rocks and ice started to form in the early solar system. Otherwise, Jupiter may have formed like the sun did, which is just a collapse of gas and dust, and so there isn’t any material in the center.

To be able to answer these fascinating questions, a state of the art spacecraft had to be built. Over ten years have been spent designing and building the Juno Spacecraft.

First of all, in order to reach Jupiter, the solar-powered spacecraft has been equipped with three solar panels reaching out to a span of twenty meters. This also made it the farthest-flying solar-powered spacecraft yet.

In order to capture the most detailed pictures of Jupiter ever, Juno has also been equipped with a camera known as JunoCam. It has been designed specifically to overcome issues created by the rotational spin of Juno and the extreme radiation. It is also one of the first space instruments which is primarily controlled by civilians. NASA started a special program where amateur astronomers can upload their images and data of Jupiter. These images are discussed and used to plan the future of the mission. A public voting follows which will determine the best locations in Jupiter’s atmosphere that the JunoCam will capture. Once the images have been taken, they will be released for the public to process and admire.

One thing that is already known is that, much like the Sun, Jupiter is composed of mostly

Jupiter’s auroras will be investigated by the Jovian Infrared Auroral Mapper (JIRAM). It

THE RESULTS Since the Juno spacecraft has only just started orbiting Jupiter, no real results have yet been released. Though it is interesting to think about what the possible results might tell us. Juno is orbiting the gas giant with the four main preassigned mission goals, listed before. Let’s take a closer look at what these questions really mean.

will try to capture both the visible and infrared emissions from the poles. Due to the intense radiation involved, the instrument is expected to survive only the first eight orbits.

The Jovian Auroral Dynamics Experiment (JADE) will be in charge of detecting the ions and electrons, which produce the auroras.

Six other instruments complete the spacecraft. Among these are for example an Energetic Particle Detector, an Ultraviolet Imaging Spectrograph and a Gravity Science Experiment. [4]

WHAT’S NEXT? Over the remaining one-and-a-half years of its life, Juno will be gathering data about the gas giant and our solar system. This data will hopefully not only help us understand more about Jupiter itself, but also about the formation of Earth and all the other planets. Make sure to follow NASA, as they will be releasing images and information from the mission soon! The next New Frontiers mission is getting ready to launch within one year.

The OSIRIS-Rex mission will study asteroid Bennu. It is planned to arrive at the asteroid in 2018 and will bring some material back to Earth afterwards. Lots of exciting discoveries are guaranteed to keep coming our way!

References [1] NASA Juno mission https://www.nasa. gov/mission_pages/juno/main/index.html [2] Juno mission website https://www.missionjuno.swri.edu/ [3] How de planets form? Juno’s Jupiter mission aims to find out – Mike Wall, June 2016 [4] NASA’s Juno craft to reach Jupiter on July 4th to find what’s hidden beneath the clouds – Steve Brachmann, July 2016 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°4 2016

11

AERODYNAMICS IN F1

Internship at Mercedes AMG Petronas Formula One Team AERODYNAMICS

Daniele Giaquinta, MSc Student Aerospace Engineering, TU Delft

12

N°4 2016 LEONARDO TIMES

With a record breaking 2014 season and successive back-to-back championships in 2015 and 2016, Mercedes AMG Petronas Formula One Team has become the most dominant team in F1 history. As an aerodynamicist in the team, my main task was to design and develop new aerodynamic concepts to improve the performance of the single-seater.

T

he past two seasons the Mercedes AMG Petronas Formula One Team has been breaking all the records and raising the bar again, after in 2014 the team has dominated the first season of the hybrid engine era, winning a record of sixteen out of nineteen races and securing a record eleven one-two finishes. In 2015 Mercedes won a second successive Championship, emerging victorious again in sixteen of the year’s nineteen rounds and beating their own previous record with an impressive twelve one-two finishes. The team is based in Brackley, roughly 110km north-west of London, where over 650 employees are provided with hi-tech facilities and equipment: autoclaves, a state-of-the-art wind-tunnel for testing 60% scale models, driver-in-loop simulators which simulate laps of all the race tracks on the F1 calendar, R&D laboratories for intensive testing of all components, and track bays where mechanics assemble the cars.

Every year, Mercedes offers a number of different internships in many of its departments among which are Vehicle Dynamics, Controls, Composites and of course the Aero Department. The internship is thirteen months long, beginning usually at the end of June and lasting until the end of July of the following year. The main aim of such an experience is to work with the company’s design teams and then return to university to complete the study with a better understanding of applied engineering.

In particular, as an intern in the Aero Department, the main task is to actively contribute to the design of the aerodynamic surfaces of the car, increasing performances and delivering lap time improvement.

AERODYNAMICS OF A MODERN F1 CAR Although aerospace applications are usually considered to be the most complex, having worked with the aerodynamic flow field generated by a Formula One car, there is no

doubt that the F1 industry possesses cutting-edge aerodynamics knowledge.

The car's open wheels are bluff bodies, which not only spin around their own axes but also rotate around the z-axis in cornering conditions (non-zero steer angle). The presence of bluff revolving bodies generates a highly unsteady three-dimensional flow field. Furthermore, if the main flow structures generated by an airplane in cruise condition are usually the two tip vortices and a vortical sheet, a modern Formula One car’s front wing alone generates up to twenty vortices, which strongly interact with the rest of the car. A further complication is the need to take into account many different conditions of positive and negative crosswind as well as different vehicle configurations such as steer and roll angle, or front and rear-ride height. Such configurations represent different straight-ahead and cornering conditions seen by the racecar at different times around a single lap, and their weight changes from track to track. The envelope is definitely more elaborate to optimize compared to that of an airplane.

INTERNSHIP AS AN AERODYNAMICIST The first month with the company begins with a rotation around the different areas in the department, including manufacturing, model preparation, and wind tunnel systems. This allows students to familiarize themselves with the different processes and people they will work with during the coming year. In addition, a comprehensive course in the 3D CAD software is provided, to give the interns a basic knowledge of the design tools and develop the skill of creating high quality aerodynamic surfaces. Following this initial training stage, the interns transfer to the main job of an aerodynamicist, which can be summed up in three different but tightly related stages:

DESIGN PROCESS (CAD) During the analysis of the CFD and wind LEONARDO TIMES N°4 2016

13

A view of the model from the wind tunnel control room. tunnel results, the main focus is tuning all the aerodynamic devices to increase downforce and reduce drag. Having identified the flow structures that can be improved, the relevant aerodynamic devices are modified to achieve the desired flow field. Of course, such a process involves the main aerodynamics fundamentals as well as detailed knowledge of the flow structure dynamics of the particular area of interest.

“

cretized through a meshing process. A powerful multi-processor cluster then solves the equations governing fluid motion in each cell of the mesh, to build up a complete picture of how the airflow is changed by the new concept. Once the simulation has run and the results are available, the solution is post-processed. This provides an initial automated analysis of the new simulated flow field by means of different variables, such as

CFD TESTING After having drawn a new aerodynamic concept, the geometry is exported and dis14

N°4 2016 LEONARDO TIMES

It’s the responsibility of the aerodynamicist to prepare and then follow up the wind tunnel session, reacting to every necessity arising in carrying out both live and post-session analysis of the acquired data.

IN A NUTSHELL

It’s easy to move from idea to wind-tunnel in just days - rapid compared to most industries.

To generate any new geometry, a parametric CAD package is used. Starting from a clear idea of the effect that the device has to produce, the surface is drawn and afterwards merged into a computer model of the full car assembly. Every innovative solution, every new and original design relies initially on the skills of the aerodynamicist. After the first iteration, once the geometry has been tested in CFD and the generated flow field can be investigated, the geometry is iterated until the desired benefit is observed and any negative side effects are removed.

fective solutions are prepared for a full-scale manufacturing and are released to be tested on the real race cars.

”

static, dynamic and total pressure, skin friction coefficient, velocity and vorticity fields as well as streamlines visualization. The outcome of the CFD post-processing is used both as input to a further CAD improvement, as well as to achieve a better understanding of the wind tunnel results.

WIND TUNNEL TESTING Once the aferomentioned stages have generated enough promising geometries, the aerodynamic devices are manufactured (usually by rapid-prototyping methods) and installed on the 60% scale wind tunnel model. This allows the concept to be tested through the large range of conditions, which characterize the onset airflow, which the car will see around a complete lap. The most ef-

Formula One, the pinnacle of motorsport, is a very dynamic environment in which a new design can be drawn, optimized, manufactured and tested in the same month, and if positive, it will hit the track a month later – very rapid compared to most industries. The atmosphere in Brackley is extremely enjoyable, with a strong team-orientation atmosphere and a campus designed around the people and their needs (modern canteen, gym, common area, etc.). Every employee is kept in the loop with constant briefings held by the Executive and Technical Directors,as well as the drivers from time to time.

The Aero Department is a very creative place with a lot of young, technical, professional and passionate people, always ready to help and with a very academic approach to R&D. All in all, it was a very exciting and enriching experience, both from a professional and personal point of view. To have your parts on a F1 car and to own your tenth of a second is certainly something to be proud of and something to definitely tell your kids about one day.

LEONARDO TIMES N°4 2016

15

OCCUPY MARS Colonizing the Red Planet within the next ten years NICK'S CORNER

Nicolas Ruitenbeek, Editor Leonardo Times

On September 28, Elon Musk presented his ambitions for interplanetary travel.

The founder of SpaceX hopes to get humans to Mars by 2024, about a decade sooner than NASA’s planned Mars mission. Is such a venture even possible and moreover, is humanity even ready to contemplate leaving Earth?

As you take your seat, your pulse quickens.

You exchange a sympathizing glance with your fellow crewmember as she sits beside you. As the door slams shut, dread begins to fill your every vein and muscle. Have I made a horrible mistake? Are we really that fortunate to be leaving? Such questions have little purpose as the seatbelt closes firmly against your chest. Sweat starts to bead on your forehead as the countdown begins. Is this the opportunity of a lifetime, or an unrelenting nightmare? Your neighbor grabs your hand and squeezes it tightly as the numbers descend into the single digits.

As the timer comes to an end, you find yourself crushed against the back of your seat.

127,800kN of thrust propels you through the clouds as your entire life flashes before your eyes. Perhaps it has to for a new one to begin ...

Although this was not part of the sales-pitch, 16

N°4 2016 LEONARDO TIMES

it’s undoubtedly not too far off from what one might feel when embarking on such a journey. Elon Musk outlined that there are two fundamental paths facing humanity today. One is that we stay on Earth, forever waiting for an inevitable extinction event to occur. The alternative is that we become a spacefaring civilization and a multi-planetary species. The latter seems to be the favorable solution, out of which SpaceX’s mission to colonize Mars has emerged.

Humanity’s needs are ever-increasing. We are first and foremost a greedy civilization always wanting more. Our hunger for development and improvement of our immediate society is what has fueled centuries of innovation, and its toll on our planet is noticeable. Carbon emissions are through the roof, croplands and fish stocks are exhausted, and deforestation is hardly slowing down. Earth’s ability to regenerate these

resources, as well as absorb the emitted carbon, is waning. Sustainable solutions are starting to appear and attempt to alleviate this problem, though they are nowhere near the level of compensation needed to sustain the planet and our perpetual needs.

Petroleum products are a necessity for our current lifestyle, the bi-products of which are a huge contributor to global warming, the spreading of diseases, and the weakening of our atmosphere. The Global Footprint Network (GFP) estimates that we consume on average 1.6 planets a year, which is clearly far too much. It will take roughly another 5 billion years for the Earth to meet its fiery end when the Sun expands into a Red Giant, engulfing our paradisal Blue Planet in an apocalyptic inferno. However this natural cause of extinction is not the one that Elon Musk was referring to, but rather the man-made extermination of civilization caused by the adverse effects of our incessant consumption habits.

The solution therefore seems to become the colonization of space. SpaceX proposes a multi-stage launch and transportation

SPACEX

system, including a reusable launcher. The interplanetary module would sit on top of the latter and be able to carry up to a hundred passengers. After being placed in a parking orbit around Earth, the module will be refueled and then embark on its journey towards the Red Planet.

While you’re enjoying your panoramic celestial view at cruising speeds of over 100,000km/h, you might want to know what awaits you at your destination. Contrary to current airports where the screaming sounds of relatives and cacophony of cars, buses and taxis are familiar sounds, the barren planet will offer no such familiarities. Colonies have to start somewhere, and although a ticket might have cost you upwards of $5 billion, your warm welcome will consists of merely a dozen cargo containers. SpaceX plans to send regular Dragon capsules to Mars starting in 2018 every 26 months to establish routine cargo flights.

These will contain tools, equipment, and other supplies that will help establish a colony on the Red Planet.

This is all considered a rough outline of Musk’s “game plan”, which hopes to launch the first Mars colonial transporter in 2024.

However, the main issue outlined in his presentation was the cost of the journey. The key to making this a successful colonization expedition is that it must (eventually) be accessible to all. The initial costs are estimated to be upwards of $5 billion, but with the current architecture and expected improvements in technology over time, the price per ticket could decrease to well under $200,000. Although this might seem pretty steep, you might recall the days when Virgin Galactic charged $250,000 for a 30min orbital flight. Even so, this is far more than a ticket to the movies on a Saturday night, so the initial demand to move to a desolate planet might prove to be extremely scarce.

Although this whole concept seems rather inconceivable, SpaceX is not the only horse in the race. A week after Elon Musk presented his vision, Dennis Muilenburg, the CEO of Boeing, said they would beat SpaceX to the punch. “I’m convinced that the first person to step foot on Mars will arrive there riding on a Boeing rocket,” said Muilenburg during a session of The Atlantic’s “What’s Next?” conference. The industry-leading aerospace company helped build the formidable Saturn V rocket and is now contracted by NASA to design the similarly massive Space Launch system (SLS), capable of sending up to twenty metric tons to Mars. “I think it’s actually much better for the world if there are multiple companies or organizations building these interplanetary spacecraft,” was Musk’s nonchalant response to Boeing’s rivalry, essentially encouraging other aerospace companies to join them in their efforts of helping humanity become a spacefaring civilization.

Increased competition and collaboration has proven to be a considerable source of innovation and will undoubtedly accelerate our way into the stars.

The criticism surrounding this project however, is merciless. For instance, there is concern as to what we would eat on Mars.

Contrary to Matt Damon’s experience on the Red Planet, researchers don’t believe it would be possible to farm out of one’s own waste. The soil on Mars lacks the nu-

trients found on Earth. It is also extremely fine, almost like dust, meaning water would seep down and away from the plant roots too easily. Additionally, the lack of nitrogen would make it practically impossible for plants to grow, as it is an essential component. Although the prospects of living off potatoes, ketchup, and Vicodin might seem appealing and sufficient to some, it appears that we will have to devise another method to farm food on our new home.

Then there is the argument that humanity should focus more on itself before contemplating spreading itself around the Solar System. Issues such as global conflicts, poverty, and gender equality should be eradicated so we can focus on technological advancements to cure diseases, overcome global warming, and make society truly sustainable. Further evolving to the point of being able to harness all the Sun’s energy, would allow us to continue our ever-growing consumption pattern.

This would espetially put humanity on the Kardashev scale of a Type I species, after which we may contemplate colonizing other planets. Although this would perhaps be ideal, it would take far too long, and it is believed that we would destroy society as a whole before even coming close to attaining such goals.

They say that if you fall, you should get right back up and keep going. That’s exactly what SpaceX did by proposing the colonization of Mars after incinerating Facebook’s satellite on the launch pad. However farfetched this endeavor may seem, it is this type of forward thinking that has pushed humanity in the past to achieve unimaginable feats. Musk’s Mars mission is bound to set new standards in the aerospace industry as well as what we as a species perceive to be possible.

References [1] Humans have already used up the supply of Earth’s resources. The Guardian.

[2] Making humans a multi-planetary species. SpaceX. [3] SpaceX hopes to send humans to Mars in 2024. Spaceflight Now. [4] Boeing will beat SpaceX to Mars. Business Insider.

LEONARDO TIMES N°4 2016

17

INOPEDIA

FPP

NUCLEAR PROPULSION WITH THORIUM A new phase in aviation and space travel Thriloknath Reddy Kummetha, MSc Student Aerospace Engineering, University of Manchester In this tech-savvy realm, numerous innovations are taking place in the domain of propulsion. However, this magnificent improvement comes at the cost of complications, which affect this planet and mankind simultaneously. An attempt to address the issue with the objective of enhanced simplicity is proposed as nuclear propulsion with aided features.

The proposed idea aims to bring to light the usage of nuclear fuel as the key resource for replacement of the existing fuels, taking 18

N°4 2016 LEONARDO TIMES

propulsion systems to an entirely new level of efficiency. The proposed idea is greener than the existing systems in the fields of aviation and space travel. In this type of propulsion system, the combustion of fuel doesn’t take place, which prevents the emission of

KUMMETHA

Propulsion systems have revolutionized the entire world with the intention to connect the world(s). The first propulsion system was used in fireworks, thousands of years ago in ancient China.. It took a while to pick up on the idea of propulsion again but once Thomas Newcoman, a british inventor, first built a steam powered pump in 1712, it did not take long to apply the engine to a vehicle. Soon after the first steam engines, combustion engines were invented. These engines had the ability to create an intense power for their relatively low weight. Ever since, these engines were used to propell cars and aeroplanes.

In spite of rapid innovations in the field of propulsion, all combustion engines work on a common principle: atmospheric air is mixed with appropriate fuel and the mixture is ignited, which produces work and exhaust gases. These exhaust gases from propulsion systems are the major fraction of pollutants in the environment.

exhaust gases. Nuclear energy has a high concentration of energy within a minute volume, enabling it to be used in propulsion systems for a higher range, endurance and cargo capacity. When nuclear fuel is excited, it undergoes thousands of fission chain reactions in which the individual nuclei of the fuel atoms split into two nuclei and give out high amounts of energy. The radiation from the nuclear fuel is also considered and methods to minimize the effect by the system are proposed with this idea.

Figure 1 - Sketch of the Combustion Chamber in the proposed Nuclear Propulsion System.

NASA

THEENGINEER.CO.UK

Figure 3 - Layout of the proposed Nuclear Propulsion System by NASA.

Figure 2 - Experimental Nuclear Propulsion System by GE and the US government.

For the nuclear fission chain reactions, the compounds containing isotopes of uranium, plutonium and thorium are mainly used as nuclear fuels in power plants and other applications. Harvesting the nuclear energy is a complicated process involving numerous precautions and procedures to be followed with extreme precision. The heavy radioactive nucleus is excited when introducing a subatomic particle, which then triggers the fission chain reaction leading to the release of high levels of nuclear energy along with different types of radiation. The type of radiation depends on the radioactive isotope used in the nuclear fuel. After this emission, the heavy radioactive element's nuclei become lighter radioactive nuclei. The same process repeats as a chain, until the nuclei are equivalent to that of lead (Pb). This gradual process of nuclei changing from original radioactive isotopes to lead (which is stable) is called Radioactive Decay. The nuclear energy and the radiation released can cause immense damage to the surroundings without proper shielding and control over the chain reaction. Generally, energy from the chain reaction is absorbed by a coolant or a moderator such as distilled water or sometimes heavy water (deuterium oxide), and the radiation is absorbed by the control rods made of materials such as silver, indium, cadmium, boron, cobalt, europium- either in elemental form or in the form of alloys, borides, nitrates, carbides, etc.

In the current generation, nuclear reactors are used as the propulsion system in heavy cargo ships, icebreakers, submarines and aircraft carriers. Several attempts were made in the past by some nations to use nuclear energy to propel aircraft but due to the complexity and hazards, those attempts were ceased at experimental stages. In these experiments, the nuclear reactor was used to calibrate the intensity of radiation, instead of using it as primary propulsion system. As the nuclear fuel used was an isotope of uranium,

the radiation emitted was gamma radiation, which is extremely hazardous and requires several inches of lead shielding. The propulsion system shown in Figure 2 was the experimental unit designed by a combined program of General Electric and the U.S. government. As the nuclear fuel used was U-233, heavy shielding was needed which compromised the thrust-to-weight ratio.

When it comes to space travel, nuclear propulsion systems are still in the theoretical stages. As shown in Figure 3, many ideas with elaborated research were proposed in the past, but none of them reached the experimental stages.

In this article, the main idea is to use thorium-228 (Th-228) in the nuclear fuel, as the radiation emitted from thorium cycle is alpha radiation which can be shielded easily, even with a piece of paper. In the past theories and proposals, uranium was always assumed to be the nuclear fuel as its halflife ranges from 60 years to a few thousand years, but Th–228 decays into Radium after releasing nuclear energy and alpha particles with a half-life of 1.9 years - a major drawback compared to Uranium-235. Though U-235 is widely used as nuclear fuel, Th-228 is chosen in this case as the nuclear fuel in aviation and space travel for two reasons: the prime reason is that the weight of the shielding can be spared. Secondly, the aircraft’s mission time is different from that of the power plants. In the case of power plants, frequent change of fuel interrupts the power generation whereas in the case of aircraft, change of fuel is one of the prime concerns before beginning a mission. The basic idea behind this concept, as shown in the Figure 1, is that the nuclear fuel will be used in the form of capsules, which are placed in the combustion chamber where the fuel injector is usually located. The control rods are placed around the capsule and the inner walls of the combustion chamber are coated with thin layers of lead for shielding. The turbine blades are also coated with a thin layer of lead in order to prevent the remaining alpha particles from escaping the combustion chambers and entering the atmosphere. In this type of propulsion system, the pressurized atmospheric air acts as the coolant and moderator, which enters the combustion chambers and ab-

sorbs the nuclear energy release in the form of heat. Here, the temperature is raised without combustion, which implies that there are no exhaust gases. The only emissions from this type of system are heated atmospheric air and the mild alpha radiation of which the effects on the environment are negligible when compared to that of the emissions of present fuels.

The principles of nuclear propulsion are the same in aviation and space travel but have different traditional approaches. Nuclear reactors need coolant, which is consumed by the reactor core from the surroundings.

However, in outer space, its availability is nil.

Hence, a moderator or coolant with small atomic weight should be taken on board.

Due to the lack of oxygen in outer space, the space vehicles (or launch vehicles) usually carry oxidizers along with the fuel, as combustion needs oxygen. In the case of Nuclear Propulsion, as the combustion of fuel is not necessary, the requirement of oxidizers is deducted. Hence, instead of carrying large quantities of fuel and oxidizer, only coolant is carried in large quantities and nuclear fuel is carried in minimal quantities, which promotes an exponential increase in the weight of payload that can be carried and the distances that can be covered.

This system reduces the fuel weight and volume immensely, allowing aircraft and launch vehicles to transport heavier cargo. Nuclear fuel in this type of propulsion system can be used for prolonged durations of time, thereby reducing the fuel consumption in a drastic manner. Aviation and space travel can take a great leap to higher standards by replacing the current fuels and propulsion systems, affecting the economic requirements of airliners, passengers and various space research organizations. Switching from existing fuels to nuclear fuels can be a huge step for mankind towards a better future and a sustainable environment.

References [1] www.theengineer.co.uk [2] www.nasa.org [3] www.gizmag.com [4] ww.innopedia.wdfiles.com

LEONARDO TIMES N°4 2016

19

THE TRACTOR-TRAILER GAP An Experimental and Numerical Approach AERODYNAMICS

William Mulkens, MSc Student Aerospace Engineering, TU Delft

The gap between the tractor and the trailer of a modern heavy-duty vehicle is a major contributor to the total drag of the vehicle. By analyzing this gap and by identifying the best type of drag reduction device for this gap, the fuel consumption of the vehicle can be greatly reduced.

APPROACH The past few decades have seen an increase in interest in the realm of sustainability and global warming. Heavy-duty vehicles are responsible for 8% of the global anthropogenic CO2 emissions [1]. When the fuel economy of these heavy-duty vehicles is increased, the greenhouse gas emissions will be significantly reduced. Improving the aerodynamics of these vehicles is not only eco20

N°4 2016 LEONARDO TIMES

logically beneficial, but will also decrease the operational costs of the haulers. One of the major contributors to the total drag of the vehicle is the distance between the tractor and its trailer. Therefore this study focuses on the tractor-trailer gap.

In the past, multiple researchers have investigated the effect of drag reduction devices for the tractor-trailer gap on North-Amer-

ican heavy-duty vehicles. However, no extensive academic study was found that focused on modern European heavy-duty vehicles, which differ significantly from their North-American counterparts. This research study aims to identify the best type of passive flow control drag reduction device for the tractor-trailer gap of a modern European heavy-duty vehicle, considering various crosswind conditions.

A proper vehicle model is designed, which is called the S-E (Small gap & Extenders) baseline model. This model is based on measurements of real European heavy-duty

METHOD The study consists of a numerical and an experimental analysis. As was pointed out by literature, a RANS simulation with the κ-ω SST closure model is the most suitable numerical method for an extensive comparative study.

A mesh sensitivity study is performed in order to analyze the sensitivity of the mesh. Furthermore, crosswind simulations (i.e. various yaw angles) are achieved by changing the boundary conditions of the computational domain.

The goal of the numerical simulations is to obtain a detailed analysis of the flow field inside the gap, and to study the effect that different add-on devices have on the drag coefficient.

Figure 1 - Contour plot of the lateral velocity with streamlines at the middle of the gap height for the baseline model with a large gap length at 9° yaw angle.

A wind tunnel experiment is performed at the Open Jet Facility of the TU Delft with a 1:8 scale model in order to validate the numerical results. A secondary goal of the experimental campaign is to test more add-on devices, since executing the numerical simulations is a very time-consuming process.

The experiment is performed at a Reynolds number of 8.5 ∙ 105 based on the cross-sectional area of the model. During the experiment, force and pressure measurements are performed and recorded on the test model.

RESULTS

Model used for the experiments. vehicles driving on the road, and also based on the GETS (Generic European Transport System) model, which is a simplified generic model developed by Van Raemdonck [2].

To analyze the effect of the gap length and the presence of extenders on the cabin, four

more baseline models are created. Multiple conceptual drag reduction devices (also called add-on devices) are numerically and experimentally tested on the five baseline models to determine their individual effect on the drag coefficient.

One of the benefits of the numerical simulations is that it can easily provide a detailed analysis of the flow field. At a yaw angle of 0°, the numerical simulations indicate that there is a small amount of air coming from the sides and the top of the cabin which enters the tractor-trailer gap. Furthermore, there are two large counter-rotating vortices inside the gap. This was also observed by other researchers analyzing the tractor-trailer gap, Hammache and Browand [3]. When the yaw angle is increased, the gap no longer contains the two large counter-rotating vortices, but only one at the windward side of the gap as is illustrated in Figure 1. Besides that, a larger amount of air enters the tractor-trailer gap via the windward side of the vehicle, which leads to a distinct stream from the windward to the leeward side. This stream of air can result in regions of separated flow at the leeward side of the cabin and the trailer.

However, the onset of flow separation is not only dependent on the yaw angle, but also on the configuration of the vehicle (i.e. gap length and presence of add-on devices).

LEONARDO TIMES N°4 2016

21

1, one can clearly see the effect of the splitter plate on the flow field inside the gap. The splitter plate significantly reduces the crossflow in the gap and thereby reduces the drag coefficient of the vehicle.

Figure 2 - Contour plot of the lateral velocity with streamlines at the middle of the gap height for the baseline model with a large gap length equipped with a splitter plate at 9° yaw angle

The experimental results show that at a yaw angle of 6° and 9°, a configuration with a large gap length has a smaller drag coefficient than a configuration which has a medium sized gap length. This counterintuitive behavior was also observed by Hammache and Browand [3], but no explanation was given. Simulation results indicate that it is probably caused by the formation of the wake of the cabin inside the gap. Furthermore, the experimental results confirm that indeed the effect of add-on devices on the drag coefficient of S-E baseline model is negligibly small. When the gap length is increased, the splitter plate is one of the most effective add-on devices. Finally it was noticed that there are large discrepancies in drag coefficient between the numerical and experimental results when the effective gap length is large and when a yaw angle is applied. This is probably because the numerical method has difficulties with correctly predicting the onset of flow separation on the leeward side of the vehicle.

CONCLUSIONS In conclusion, the drag coefficient of modern European heavy-duty vehicles lies closely to the configuration of a vehicle without a tractor-trailer gap. Therefore the potential gain of adding drag reduction devices is very limited.

However, when the gap length is increased, a splitter plate attached to the trailer's frontal surface is identified as one of the most effective add-on devices as it greatly reduces the drag coefficient. Finally, it was observed that a RANS simulation with the κ-ω SST closure model is not a reliable numerical method, as it cannot accurately predict the drag coefficient of certain configurations when a yaw angle is applied.

The set-up of the wind tunnel experiment.

For a modern European heavy-duty vehicle (the S-E baseline model) the tractor-trailer gap contributes up to 3.9% of the total drag coefficient of the vehicle. When the gap length is increased to 2.1m, which is an average gap length for a North-American heavy-duty vehicle, the drag contribution of the gap increases to 19.3%. The numerical results show that this increase is mainly caused by an increase of the pressure on the trailer’s frontal surface. For the S-E baseline model, the average pressure coefficient on the trailer frontal surface equals -0.186, while it is equal to 0.041 for the baseline model, which has a larger gap length of 2.1m. A similar effect can be observed when the side and roof extenders of the cabin are removed from the S-E baseline model. Re22

N°4 2016 LEONARDO TIMES

moving these extenders increases the contribution of the tractor-trailer gap to 10.2% of the total drag coefficient. Furthermore, the average pressure coefficient on the trailer’s frontal surface also increases when the side and roof extenders are removed from the S-E baseline model.

The numerical results show that the aerodynamic performance of the current European heavy-duty vehicle lies closely to that of the ideal vehicle model without a tractor-trailer gap. The effect of adding drag reduction devices for the tractor-trailer gap is negligibly small. However, when the gap length is increased to 2.1m, a splitter plate attached to the trailer's frontal surface can reduce the drag coefficient by 39.6% at a yaw angle of 9°. When one compares Figure 2 with Figure

If you have further ideas or want to contribute to this research as a master student, contact the author for further information by email wmulkens@gmail.com References [1] Miller, J.D., Façanha, C., “The state of clean transport policy: a 2014 synthesis of vehicle and fuel policy developments”, Technical report, The International Counsil on Clean Transportation (ICCT), Washington DC, 2014.

[2] Van Raemdonck, G.M.R., “Design of Low Drag Bluff Road Vehicles”, PhD thesis, TU Delft, 2012.

[3] Hammache, M., Browand, F., “On the Aerodynamics of Tractor-Trailers”, The Aerodynamics of Heavy Vehicles: Trucks, Buses, and Trains, p 185-205, Springer Berlin Heidelberg, 2004.

TIME FLIES

BOEING

100 YEARS

LEONARDO TIMES N°4 2016

23

Reflecting on a century of aerospace innovation

berlands on the Pacific side of the Olympic Peninsula, which he then shipped to the East coast via the Panama Canal. This venture was a tremendous success and provided him with the necessary funds that he would later apply in his own businesses.

his own leisure. After assembly, his test pilot, Herb Munter, damaged the new aircraft and replacement parts had to be ordered. However, he was told that such components wouldn’t be available for months to come.

William and his close friend, George Conrad Westervelt, figured they could build a better plane in less time themselves and so came the B&W Seaplane, an amphibious biplane with outstanding performance. On July 15th 1916, Boeing was incorporated in Seattle

by William Boeing as “’Pacific Aero Products Co”. Despite his unrelenting ambition, little did he know just how drastically he would end up shaping the world of aviation and global transportation.

In 1909, William attended the Alaska-Yukon-Pacific Exposition, a world fair dedicated to publicizing the development of the Pacific Northwest. It was during this event that he saw a manned flying machine for the first time, which sparked his passion for aviation.

He immediately enrolled for flying lessons at the Glenn L. Martin Flying School in Los Angeles, and completed them in no time flat. Boeing bought one of Martin’s planes for

Due to the proximity with the Pacific Ocean, many of Boeing’s first planes were seaplanes. They were capable of accessing difficult areas surrounded by water, as well as not being restricted to a runway for landing and take-off. William took advantage of his success and knowledge in the lumber industry to get supplies to fabricate his early planes. The company’s early aircraft were

Nicolas Ruitenbeek, Editor Leonardo Times It’s fair to say that if you have any interest whatsoever in the aerospace sector, “Boeing” is a very familiar term. If not, then you have been living under a rock, or at least one that is hundred years old. This industry-leading company passed its first century on July 15th 2016. There is thus no better time to reflect on their history and values than right now.

WILLIAM EDWARD BOEING William E. Boeing was born on October 1st, 1881, in Detroit, Michigan, to catholic parents.

His father, Wilhelm Böing, was a wealthy mining engineering from Hagen-Hohenlimburg in Germany. His mother, Marie M. Ortmann was from Vienna, Austria. They moved to the United States to establish a lumber mill near Lake Superior and before long, they had turned it into a fortune built upon timberlands and mineral rights. In 1900, upon returning from being educated abroad in Switzerland, William anglicized his surname to “Boeing” and attended Yale University. Three years later, he dropped out and joined his father’s lumber business. He bought into lumber operations and purchased extensive tim24

N°4 2016 LEONARDO TIMES

THE COMPANY’S FIRST STEPS

thus almost entirely made out of wood.

On April 6th 1917, the horizon darkened with U.S. declaring war on Germany, but William saw only opportunity. He knew that the Navy needed seaplanes for training, and so began the construction of the Model C Trainer. The Model C was the first “all Boeing” design. It had a wingspan of 13m, a top speed of 117.5kph, and an operational ceiling of 6500f. Being able to accommodate a crew of two, it was a formidable trainer for the time. Boeing shipped two Model Cs down to Pensacola, Florida, where the Navy gave them a try and ended up ordering another fifty. The U.S. Army also bought two landplane configurations with side-byside seating. This unforeseen success forced Boeing to move its operations to a larger location known as “Boeing Plant 1”, located on the Duwamish River. It also prompted William to change the company’s name to something more concise and representative of his heritage. The establishment hence became “The Boeing Airplane Company”.

The end of World War I came in 1918 along with a surplus of cheap, used military aircraft.

Many companies went out of business and Boeing started selling other products such as furniture and flat-bottom boats to make up for the financial losses. However, the demand for commercial aircraft was slowly starting to grow and within a year, the Boeing B-1 had its first successful flight. It was a flying boat powered by a single engine, and could accommodate some passengers and cargo. It became tremendously successful as a means of transporting mail and by 1927, it had made thousands of international flights between Seattle and Victoria, British Columbia. In 1925, Boeing completed the Model 40 aircraft for the U.S. Government to use on airmail routes.

Boeing’s response to the ever-increasing demand for commercial air-travel was the creation of an airline called “Boeing Air Transport”. On July 27, 1928, the 12-passenger Boeing 80 biplane lifted off for a successful flight. It was the first plane built with the sole intention of passenger comfort. The 80A followed shortly after and was able to carry 18 passengers. The path to fast and safe air-travel was well on-route.

EVERETT FACILITY FACTS

Figure 1 - William Boeing.

1. With an internal volume of 13,385,378m3, it is the largest building in the world by volume.

2. Its surface area covers just under 400,000m2.

3. The Everett factory is also known as “Boeing City” as it requires its own fire department, security force, fully equipped medical clinic, electrical substations and water treatment plant.

4. There are 3.7km worth of pedestrian tunnels running below the factory floor.

5. Newly assembled planes need to cross a bridge over a highway after exiting the assembly line. This created numerous disruptions and accidents on the road below as drivers would slam on the brakes to get a good look at a brand new plane.

Boeing hence decided to only roll-out new aircraft after sunset, when it was pitch black.

6. The mural spanning across the six factory doors is the largest in the world.

7. Boeing utilizes lean manufacturing methods, bringing in only what they need and no more.

8. When the factory was first built, clouds started to form near the ceiling. An air-circulation system had to be installed to clear the internal weather.

LEONARDO TIMES N°4 2016

25

BOEING 747 FACTS

Figure 2 - The B1-B. 1. 747s have flown more than 3.5 billion people.

2. The 747-400 once carried 1,087 people in one flight.

3. The upper deck alone has the same square footage as a 737.

4. The 747 has a wing sweep of 37.5 degrees, more than any other commercial aircraft in the world.

5. Just over 6 million parts make up the new 747-8.

6. The 747 fleet has logged more than 42 billion nautical miles. Equivalent to 101,500 trips from the Earth to the moon and back.

THE QUEEN OF THE SKIES: THE BOEING 747 In 1964, Boeing was designing a large military transport vehicle called the C-5A. Unfortunately, their design was not selected by the military. However, to take advantage of the technology, Boeing decided to develop a large, advanced commercial airplane around the C-5A’s engines. To avoid any possible negative repercussions with the U.S. Army, the designers purposefully avoided using any hardware, other than the engines, developed for the extinct military transport. The incentive for creating the jumbo-jet came from increasingly crowded skies, a surge in air-passenger traffic, and airfare reduction.

The 747’s final design was offered in three different configurations: all-passenger, all-cargo, and a mix of the two. The total wing area was larger than a basketball court and therefore required to be constructed and assembled at a new, specialized plant in Ev26

N°4 2016 LEONARDO TIMES

erett. The first 747 rolled out on September 30, 1968, before the world’s press and representatives of the twenty-six airlines that had ordered the monstrous airliner. Just over four months later, on February 9, 1969, the new bird took to the skies with test pilots Jack Waddell and Brien Wygle at the controls. Despite a minor problem with one of the flaps, the 747 handled extremely well.

The 747-200 model followed in 1971 featuring more powerful engines and a higher MTOW (maximum takeoff weight). In 1983, the 747-300 rolled out with a stretched upper deck, increased cruise speed, and increased seating capacity. The 747-400 entered service in 1989. New improvements focused mainly on the flight deck and construction materials. Improved flight systems allowed for a cockpit crew of two instead of three, though this caused many delays as the technology was lagging. It also sported winglets that were 1.8m high. In November 2005, Boeing launched the 747-8 family: the 747-8 Intercontinental passenger airplane, and the 747-8 freighter. These aircraft incorporate innovative technologies from the 787 Dreamliner such as raked wingtips, advances aluminum alloys and composite materials.

From being the most recognizable airplane in the world, to a flying White House for generations of U.S. presidents, to a shuttle carrier for NASA, the Boeing 747 will remain an aviation staple for decades to come.

THE BOEING EVERETT FACTORY Boeing’s largest assembly building is in Everett, Washington, just outside of Seattle. It is where the 747, 767, 777 and 787 are assembled. The plans for the factory were first announced in 1966 for it to be the site of construction of the 747. This was prompted after Boeing was awarded a $525 million contract

by Pan American World Airways to build

twenty-five jumbo-jets. Shortly after in 1968, the first 747 rolled out and factory tours started to be offered. On average, over 150,000 people visit the Everett site each year.

SUPERSONIC AMBITIONS Many know of the Concorde, but does the Boeing 2707 ring any bells? On New Year’s Eve 1966, after more than 14 years of study, design work, and competition against Lockheed and North American, the federal U.S. government selected Boeing to build the prototype for the country’s first supersonic transport vehicle. It was designed as a large aircraft being able to seat between 250 and 300 passengers, cruising at speeds above Mach 3. This made it much larger and faster than preceding designs such as the wellknown Concorde. Twenty-six airlines ordered just over 120 aircraft.

The topic of supersonic transportation was a sensitive one at the time. The press centered on the issues of noise regulations due to sonic booms and adverse effects on the ozone layer. Within the airline industry, the economics of such a design were questioned and were only partially addressed during development. Government funding was cancelled in 1971 before the prototype was finished due to exponentially rising costs and the lack of a clear market.

Supersonic air-travel came to a standstill, as it proved impossible to produce safe, efficient vehicles that were economically sensible.

This mentality is slowly diminishing as multiple companies are now re-investigating supersonic designs. The Icon-II is Boeing’s new concept that was created with the help of NASA. The revolutionary aircraft achieves the required noise goals to permit supersonic travel over land, as well as the fuel burn reductions to contribute to a sustainable future. The chase for faster-than-sound air-trav-

Figure 3 - The Boeing Starliner. el has not died off as such an aircraft is presumed to enter service before 2035.

SPACE AND DEFENSE When it comes to the Defense Sector, Boeing is no stranger. Boeing Defense, Space & Security (BDS) is one of The Boeing Company’s five divisions. Being a $30 billion business with roughly 50,000 employees worldwide, BDS is today considered to be the world’s largest and most versatile manufacturer of military aircraft.

“

Inspired by the success of the B-17 and the ever-impending need for increased potential destruction, USAAC requested the development of pressurized, long-range, tactical bombers in 1938. The result of which became the single most expensive weapons project undertaken by the United States during World War II, exceeding the costs of the Manhattan Project by $1.6 billion. The B-29 Superfortress was the largest aircraft operational during the Second World War

It behooves no one to dismiss any novel idea with the statement that ‘it can’t be done’.

- Bill Boeing

Boeing had already been well on the radar of the U.S. Government in terms of being affiliated with the Navy ever since they provided trainer aircrafts back in 1917. It should therefore come as no surprise that Boeing presented its new design with brio when the U.S. Army Air Corps (USAAC) tendered a proposal for a multi-engine bomber to replace the Martin B-10. The Boeing B-17 Flying Fortress was a four-engine heavy bomber that outperformed both competitors (Douglas and Martin), as well as exceeded the USAAC’s performance specifications. It was introduced in April 1938 and immediately became the new Allied powerhouse in the Second World War. Many variations were built for different applications (XB-28, YB-40 and C-108), though the most notable one surely is its reconfiguration into the Boeing 307 Stratoliner, America’s first pressurized passenger aircraft, introduced in 1940 with Pan American Airways.

”

and excelled at high altitudes as a strategic bomber, but also at low-altitude nighttime incendiary bombing missions. The doomsday machine ultimately brought the war to a standstill when it dropped atomic bombs on Hiroshima and Nagasaki. Just under 4,000 B-29s were built between 1943 and 1946 after which they begun to be retired in the 1960s.

Boeing’s significant contribution to warfare development established it as a powerhouse in the industry. The design of the B-52 followed in 1952 responding to the United States Air Force’s need of a long-range, jet-powered strategic bomber capable of carrying nuclear payloads for Cold War-era deterrence missions. Even after having been in operation for more than 50 years, refurbishing the B-52 fleet is found to have the highest return on investment of any U.S. military expenditure.

Fortunately, Boeing’s sights weren’t limited to weapons of mass destruction. The Saturn V was a multistage, liquid-fuel expandable rocket used by NASA’s Apollo and Skylab programs. It also represented the culmination of efforts between Boeing, North American Aviation, and McDonnell Douglas who built the first, second, and third stages of the Saturn V respectively. Boeing continued their aspirations in the space industry by designing the Lunar Roving Vehicle (popularly known as the “moon buggy”), which was used in the last three missions of the Apollo program.

Boeing played a paramount role during the Second World War and continues to be one of the primary defense contractors to the U.S. Government and other nations around the world. However, the company’s endeavors don’t stop there as NASA has decided to keep Boeing as the International Space Station's prime supplier through September 30, 2020.

WHAT NEXT? Boeing has been one of the biggest leaders in the aerospace industry and continues to be at the forefront of new technologies.

A passion for innovation and pushing the boundaries of what we deem possible is the air that all 156,921 employees breathe.

Having extensive experience and success in the commercial aviation, defense and space sectors, one can only guess: what will they dream of next?

References [1] In Plane View, a pictorial tour of the Boeing Everett Factory.

[2] A time-line of Boeing’s 10-year History.

Business Insider [3] Boeing History. Boeing.com/history [4] NASA, and Iconic Idea.

LEONARDO TIMES N°4 2016

27

AVIATION DEPARTMENT

The first solar powered

SOLAR

Solar Impulse was an initiative of the Swiss engineer AndrĂŠ Borschberg and the Swiss aeronaut Betrand Piccard. Their goal was to build an aircraft that only relies on solar power and to give the world an example of what can already be achieved with clean energy technologies.

I

n 2003 Piccard and Borschberg started the Solar Impulse project. Their intention was not to show that solar aviation could be applied on a huge scale in the future, as it is not likely that commercial aircraft will solely be powered by the sun any time soon. Instead, Piccard and Borschberg wanted to show that it is already possible to fly around the world using only solar power, with the potential of clean energy in other applications. However, solar planes have been flown before.

For instance, in 1981 the Solar Challenger, designed by Paul MacCready, completed a 262km flight across the English Channel. But Piccard and Borschberg have taken on the 28

N°4 2016 LEONARDO TIMES

challenge to build a solar aircraft that will circumnavigate the globe, powered solely by the sun. So far, the project has produced two aircraft,the first prototype being the Solar Impulse 1 (HB-SIA) and the second, 11% larger, prototype Solar Impulse 2 (HB-SIB).

SOLAR IMPULSE 1 The construction of the Solar Impulse 1 started in 2006. This resulted in an aircraft with a non-pressurized cockpit, a wing span of 63.4m and four propellers. Each propeller was driven by a 7.5kW electric motor, which could directly be powered by the photovoltaic cells that cover nearly the entire wing

surface and horizontal stabilizer. These cells have a total average power generation of fifty kilowatts over a 24-hour period. Any excess power produced by these cells is stored in the four lithium-polymer batteries to be used during night flight. The biggest design challenge was keeping the weight to a minimum. Batteries have a significantly lower power density compared to jet fuel, meaning a lighter structure is needed to compensate for the extra weight. A large part of the structure consists of a custom carbon fiber honeycomb design. This resulted in an impressive total weight of only 1,600kg.

The construction of the Solar Impulse 1 was completed in 2009. Its first flight occurred in the same year above Switzerland, piloted by Borschberg. After more test flights, it broke the records for the longest flight, the larg-

SOLAR IMPULSE

aircraft to fly around the world.

IMPULSE Jelle Westenberger, BSc Student Aerospace Engineering, TU Delft

est distance flown and the highest altitude reached with solar flight. These record flights had a duration of more than 26 hours, covered a distance of 1,541km and a maximum altitude of 28,500ft. This proved the validity of the concept. However, the test flight also showed that this aircraft would not perform well enough to safely cross the Pacific Ocean. Flying at a cruise speed of 43mph it would take five to six days to cross the Pacific. The systems were not redundant enough to ensure the safety of the pilot on such a long flight. Additionally, for the pilot to sleep comfortably, the cockpit had to become more ergonomic and an autopilot system was required. So in 2011, the construction of its successor, the Solar Impulse 2, started.

larger and more advanced than its predecessor. It has a length of 22.4m and a wingspan of 71.9m. For comparison, a Boeing 747 has a wingspan of 68.5m . It features more advanced avionics that allow for an autopilot system to be implemented. A multi-purpose seat, which also functions as an adjustable bed and a toilet, together with a more spacious cockpit gives the pilot more comfort and allows him to be in the air for multiple consecutive days. To save weight and reduce power consumption, the cockpit is unpressurized and not heated. A special lightweight foam, polyurethane, is used to insulate the cockpit and an oxygen supply system is implemented to help the pilot cope with the extreme conditions that exist at the peak altitude of 29,500ft.

SOLAR IMPULSE 2 The second prototype was designed to be

Even more thorough weight reduction is

achieved by using new technologies .The structure has an extremely lightweight skeleton, constructed with sheets of carbon fiber.

Even the nuts and bolts are composed of self-reinforcing polyphenylene, which is one of the strongest and stiffest plastics in the world. The four propellers are each driven by 13kW electric motors. These electric motors use a special lubricant developed by Solvay that reduces the mechanical losses to only three percent. The entire propulsion system has an astonishing efficiency of 94 percent.

A total of 17,248 photovoltaic cells are able to generate a peak power of 66kW. These cells have a staggering efficiency of 22.7% and a thickness of only 140 microns.

New innovations in battery technology allowed for batteries with a higher power density to be implemented. It now has four lithiLEONARDO TIMES N°4 2016

29

SOLAR IMPULSE

off and start the climb of the plane. Soon, the sun’s intensity is sufficient to take over the work of the batteries and the excess power generated by the solar cells is used to recharge the batteries. The maximum altitude of 29,500ft is reached after many hours just when the sun’s rays are not strong enough anymore to solely power the aircraft. At this point the batteries will take over anew, the power throttle is pulled back and the aircraft starts to slowly descend to an altitude of 5,000ft. When timed correctly, it should not be long after reaching this altitude when the sun has risen again and the aircraft can start climbing. These steps are repeated for the entirety of the flight.

CIRCUMNAVIGATING THE GLOBE

SOLAR IMPULSE

Solar Impulse 1 flying along the Golden Gate Bridge in San Francisco

Betrand Piccard (left) and André Borschberg (right) in front the Solar Impulse 2. um-ion batteries, each weighing 158kg and having a capacity of 41kWh. The final weight of the aircraft is only 2,300kg.

In 2014 the construction of Solar Impulse 2 was finished and it had its first flights. Piccard and Borschberg were now confident enough to take on the challenge of circumnavigating the globe.

PILOT’S ENDURANCE Solar Impulse 2 was transported to Abu Dhabi in January 2015. Simultaneously, a mission control center was created in Monaco.

From here, a team of meteorologists, mathematicians, air traffic controllers and engineers communicate with the pilot and constantly monitor flight data, aircraft performance and weather forecasts to keep the long flights as safe as possible. Also the pilot’s physical data 30

N°4 2016 LEONARDO TIMES

was being monitored. Sensors monitor the heart rate and the oxygen level in the blood, which is important when flying a self-sustaining aircraft for multiple days- a new boundary arises, which is the endurance of the pilot. The pilot is exposed to serious environmental changes as the days progress.

The temperature within the cockpit varies between 35°C and -20°C. When flying near populated areas, the pilot is only allowed to take 20 minute naps at a time. In order to quickly fall asleep, Borschberg and Piccard use self-hypnosis. Meditation and physical exercises are used to stimulate their concentration and keep their minds clear.

FLIGHT CYCLE A typical flight starts early in the morning when the sun has just risen. The batteries are fully charged and its energy is used to take

On 9 March 2015, Solar Impulse 2 started its journey to circumnavigate the globe.

Piccard and Borschberg took turns piloting the aircraft. They started from Abu Dhabi and planned to return within sixteen separate flights. The original plan was to have completed the endeavor by August 2015.

However, the flight from Japan to Hawaii on the 28th of June has proven to be the most intensive flight so far. This flight broke the record for the longest flight ever (for any aircraft) with a flight time of 4 days and 22 hours and it broke the record for the largest distance flown by a solar aircraft, by flying a distance of 2,942km. Unfortunately, some batteries were damaged due to overheating.

The remaining flights were postponed to the 21st of April 2016. At the time of writing this article (June 2016) a total of fifteen successful flights have been completed and Solar Impulse 2 is now stationed in Spain. The current plan is to have one last flight from Spain to Abu Dhabi to complete the journey across the world. This flight should break its previous records for the longest flight and the largest distance flown. Hopefully, the completion of this endeavor will make people realize that clean energy technologies already have a huge potential and that they must be applied more extensively in the current industries.

References [1] http://www.solarimpulse.com/ [2] http://www.popsci.com/ [3] www.forbes.com [4] www.businesswire.com 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.

DSE

DESIGN SYNTHESIS EXERCISE

Summer 2016

Prior to recieving a Bachelor diploma in Aerospace Enineering, each student must complete the Design Synthesis Exercise (DSE). The DSE is a two-month group project during which students combine creativity and knowledge obtained throughout their studies to formulate a complete aerospace design. Aircraft, spacecraft, drones and turbines are the usual repertoire, and this year's designs were as versatile as always, varying from a life-saving drone to a science-fictiony geoengineering mission.

LEONARDO TIMES N°4 2016

31

ARMADA Group 3

PETER VAN DEN BERG

Roughly 66 million years ago, the era of the dinosaurs ended when an asteroid impacted the Earth, killing 75% of all plant and animal species. In 2013, the town of Chelyabinsk, Russia, was violently woken up by a meteorite entering the Earth’s atmosphere, releasing energy equivalent to 500kilotons of TNT (Popova et all. 2013). This event raised the question: will we succumb to the same fate as the dinosaurs? The ARMADA mission serves as a stepping-stone to protect humanity from asteroid impacts, to ensure the survival of the human race.

S

ince 1985, space agencies from around the world have sent several spacecraft to visit asteroids and comets, giving humanity a glimpse of these mysterious worlds. However, until now, no space agency has ever managed to deflect an asteroid. With the potential consequences of an asteroid impact being disastrous, the need to develop the required technology to deflect an asteroid is evident. Our DSE group is determined to develop a mission which Applies Reliable Methods to Analyze and Deflect an Asteroid, or in short: the ARMADA mission.

Before designing the ARMADA spacecraft, a suitable target asteroid had to be found.

After considering multiple target asteroids, Apophis was selected as the best candidate

for deflection. Its orbit is similar to Earth’s, and is relatively easy to reach. The deflection method was not yet defined at the start of the design phase, this is an important consideration as it allowed for a wide range of design options. Multiple deflection methods were considered for the ARMADA mission.

Amongst them were laser surface ablation, kinetic impactors, gravity tractors and solar mirrors. After exploring each design option and comparing them, the gravity tractor was considered to be the most feasible solution.

Whenever two bodies of mass are at a distance from each other, a gravitational force is present between them. By flying a spacecraft near an asteroid, this gravitational force can be exploited to move the asteroid in a different direction over time. It must be noted that

SAGA Group 2 Global warming is advancing faster than models predicted from just a decade ago. Uncurbed emissions of carbon dioxide and other greenhouse gases might lead to positive feedback effects which further increase the rate of warming. Recent efforts to stop the climate change focus on solving the problem in the long term by reducing the emissions or by reducing the greenhouse gases. We are making good progress, but the response is slow and we might simply not be fast enough. The possibility of unacceptable temperature increase before long term solutions become effective might therefore necessitate a temporary intervention to manage global temperatures.

G

eoengineering, or more specifically Solar Radiation anagement (SRM), presents a realistic method for tem-

32

N°4 2016 LEONARDO TIMES

porary management of global temperature.

SRM has a direct impact on the heat energy Earth receives, thus directly influencing

the asteroid itself also exerts a gravitational force on the spacecraft. This force needs to be counteracted constantly; otherwise the spacecraft and the asteroid would move to their common center of mass and collide.

Since the gravitational force between these bodies is relatively small, only a small thrust is required to counteract this force.

After having determined the characteristics of the mission to be performed, the spacecraft can be designed accordingly. Surprisingly, it was found that a relatively small spacecraft mass is sufficient to achieve a considerable deflection distance. For a mission time of five years, a spacecraft dry mass of only 193kg is sufficient to deflect the asteroid by over ten kilometers. It was found that if a deflection of roughly twelve kilometers is performed at the right moment, it can ensure to avoid collision with the Earth within the next one hundred years.

The mission profile is as follows: the spacecraft is launched on the 21st of April 2021. After a transfer orbit of 245 days it arrives at the asteroid Apophis. The spacecraft is then put into an orbit around Apophis for a period of roughly six months to study its composition and map its surface. After this observation phase, the spacecraft is moved into a hovering position at an altitude of roughly 95 meters to start the deflection maneuver. During the deflection maneuver, electric propulsion systems are used to counteract the gravity force exerted on the spacecraft. After five years, the deflection maneuver is completed and the results are evaluated.

For thousands of years, Mankind has been subject to the mercy of Mother Nature. However, recent advancements in technology have opened up new possibilities to ensure the long-term survival of the human race. It’s high time to take matters into our own hands.

References Chelyabinsk Airburst, Damage Assessment, Meteorite Recovery, and Characterization, Olga P. Popova et all. Science Vol. 342 Issue 6162, pp.1069-1073, 2013

its surface temperature. One possible SRM method is the injection of aerosols into the stratosphere to produce clouds which reflect a portion of the incoming sunlight. The development of methods to inject aerosols into the atmosphere between 18 and 25km altitude is currently an active domain of research. We consider the design of Stratospheric Aerosol Geoengineering Aircraft (SAGA) program based on a fleet of purpose-built aircraft to deliver five megatons of aerosol per year to altitudes between 18.5 and 19.5km.

MISSION DESCRIPTION SAGA will operate a fleet of nearly 350 air-

0.5% of the world’s GDP, which is a meagre amount relative to the potential positive impact.

ENVIRONMENTAL EFFECTS

craft. The 35-ton payload limits the flights to two per aircraft per day. For optimal aerosol effectiveness, the injection will take place in the tropical region where seven airports will be adapted for SAGA operations. Derived from the natural analogue of volcanic activity, the aerosol consists of sulfuric acid - H2SO4 - which brings about an albedo-enhancing effect.

AIRCRAFT DESIGN The constraints of the SAGA mission lead to an extremely narrow design space. The rare combination of high altitude and high payload ,calls for a slender and efficient wing and exceptionally powerful engines. Following from these requirements, structural weight and aeroelastic effects are critical design drivers. To meet these requirements, we developed a complete performance model using the Stanford University Aerospace Vehicle Environment (SUAVE). This opensource framework allowed us to augment relevant correlations with physics-based methods and automatically optimise the design.

The final product features a massive, but lightweight 700m2 wing with an aspect ratio of thirteen. The unprecedented 95m wingspan is achieved with the help of a strutbraced wing design. In-depth wing analysis employing tools such as SU2 and an optimised wing structure guarantee minimal fuel burn. Finally, four in-house-developed, stateof-the-art engines provide SAGA with over 2.5MN of thrust at sea level.

Aerosol-based SRM carries serious potential adverse environmental effects, such as sulfuric acid deposition in precipitation and surface water. However, should we exceed a critical global temperature threshold, SRM’s global warming mitigation potential can balance these effects and necessitate SAGA’s implementation. The aerosol in the stratosphere is estimated to reduce solar influx to counteract a 25% increase in CO2 concentration, while SAGA’s contribution to atmospheric sulphur compounds is limited to 4%.

Furthermore, to reduce SAGA’s own impact of greenhouse gas emissions, its positive environmental effects shall offset its emissions.

With SAGA’s contribution to the worldwide fuel consumption at only 0.03%, it offers an environmentally viable bridge to limit global warming while a long-term, sustainable solution is implemented.

References

IMPLEMENTATION AND COST The decision to employ geoengineering to temporarily mitigate global warming effects is bigger than any single government can make. We propose to implement SAGA as a part of a worldwide program, in which the most influential governments form a supervising and funding consortium. The prospect of saving millions of livelihoods and billions of dollars worth of infrastructure permits a considerable budget for SAGA. Maximum development and yearly operating costs are forecast to be €50B and €10B respectively.

The total expenditure translates roughly to

AEOLUS Group 17 The global need for sustainable energy has pressed the necessity for large wind turbines. Compared to land-based wind farms, wind fields at sea are usually stronger and steadier. Offshore wind turbines have been developed, but have now encountered an important limitation: the high cost of foundations when the water depths increase above thirty meters (Sclavounos, 2011). Making the wind turbines float will help to overcome this limitation. Moreover, this would allow for offshore installation in deep waters, while significantly reducing costs compared to their non-floating counterparts.

[1]A. Robock, R.E. Hester and R.M. Harrison.

Stratospheric Aerosol Geoengineering, Issues in Environmental Science and Technology, 38 Geoengineering of the Climate, 2014.

[2] P. Heckendorn, D. Weisenstein, S. Fueglistaler, B. P. Luo, E. Rozanov, M. Schraner, L. W. Thomason and T. Peter, “The impact of geoengineering aerosols on stratospheric temperature and ozone,” Environmental Research Letters, Vol. 4, No. 4, 2009, pp. 108120.

W

hen designing a floating wind turbine many challenges arise. The biggest is to make the design as inexpensive as possible, but where does one begin with finding solutions for the challenges at hand?

To metaphorically answer this question, take a look at the typical “Delft Bike”. It is characterized by its simplicity, an absence of unnecessary options (only a coaster-brake). In short “Less is more”. This was the inspiration for the final design. As stated earlier, one of the key requirements was to make the design economically viable where the production of energy may not exceed a LCOE (Levelized Cost of Energy) of 130€/MWh. To put this into perspective, current offshore floating wind turbines produce energy of about 140€/MWh whereas coal plants do this for 63€/MWh (Siemens, 2014).

Furthermore, the wind turbine needs to produce at least 6MW of energy, almost twice the amount produced by an average offshore wind turbine (EWEA).

Now to address the pondering question on everyone’s mind, how do wind turbines float? According to Archimedes’ principle, a body totally or partially immersed in a fluid is subject to an upward force equal in magnitude to the weight LEONARDO TIMES N°4 2016

33

of fluid it displaces. If the displaced volume is large enough the wind turbine floats. This buoyancy force acts at the center of mass (CB) of the displaced water. The weight of the wind turbine acts in the center of mass of the solid (CM) and is directed opposite to the buoyancy force. When the CM and the CB are aligned, the wind turbine is in equilibrium. In case of a disturbance, the equilibrium is lost and torque is generated. This torque will stabilize the wind turbine if and only if, the CB is located above the CM. In this case the restoring torque will stabilize the wind turbine until the CB is aligned with the CM (Viré, 2012).

With the design parameters in mind, the creative design process could commence. Many hours of contemplating and iterating finally led to the design which can be seen in the title

HERIADES

block, “Aeolus” which in Greek mythology was the master of winds and wind gods who lived on the floating island of Aeolia. Aeolus features a twin rotor design which makes it possible to produce 10MW and drive the LCOE down.

One may be compelled to ask “Why choose a twin rotor design as opposed to the conventional single rotor?” Single rotor wind turbines reach a limit with respest to rotor radius, they are too large to manufacture and too heavy for their own structure. By installing two 5MW rotors on one tower, the technical limit of energy production can be raised. A triple rotor design was also considered, however, this design option pushed the limits of manufacturing. Maintenance would also prove to be complicated due to the height of the structure.

Due to the swift pace of technological innovation, boundaries are pushed in a wide variety of technical fields. Specifically, the increased energy density of batteries has proven to be a fundamental impetus driving the booming business of small and micro unmanned aerial vehicles (UAVs), mainly in terms of amateur drones. With it though, comes an increase in the number of drone incidents when the vehicle is flown into a restricted area, such as the airspace around an airport or a government building. This sparked the development of ground-based anti-drone technologies that focus on removing intruding drones from a specified area by means of nets, lasers, and/or jamming. However, ground-based solutions are expensive, whilst also having limited maneuverability as well as long deployment and redeployment times.

D 34

N°4 2016 LEONARDO TIMES

References [1] P. Sclavounos, “Floating wind turbines."

Massachusetts Institute of Technology [2]Siemens, “What is the real cost of offshore wind?”, Germany, 2014 [3] http://www.ewea.org/wind-energy-basics/ faq/ [4] A.Viré, “How to float a wind turbine”, 2012

Finally, Aeolus will be placed in a wind farm

Group 8

SE group 08 has been tasked with designing a highly maneuverable and flexible anti-drone system, based around an Unmanned Aerial Vehicle (UAV) that must out-speed, outmaneuver, and ultimately impede any drone with a maximum velocity of 35 meters per second that tries to intrude a specified area of one kilometer in diameter. It was previously concluded that concept HELIADES was the most feasible aerial vehicle for this mission, out of the

consisting of one hundred wind turbines neear North-West of Scotland. The wind farm shall produce 1000MW of power in total, thereby supplying energy to more than 400,000 households in the EU, with a LCOE of 90€/ MWh. The main reason for the large decrease in the LCOE can be attributed to producing great amounts of energy while keeping the structure relatively light.

six concepts chosen for the trade-off studies. This is a tiltrotor, fixed-winged aircraft, equipped with an integrated removal system, which consists of a directional signal jammer, a net launcher and a kinetic cannon.

Our task was to conduct a detailed analysis on the chosen concept in terms of technical and operational aspects. Moreover, activities for future phases were to be determined.

A detailed analysis was performed in terms

of performance, aerodynamics, stability & control and structure of the aerial vehicle.

Furthermore, the operating and logistic characteristics of the entire system were defined in detail, as well as a sustainability approach for the entire development life cycle. Hereafter, the critical risks of the system were identified and its compliance with the requirements set by the stakeholders was analyzed.

Finally, a complete post-DSE project plan was developed in order to turn the design into a working prototype.

The result of this report was a fully autonomous aerial vehicle with a total prototype cost of €14,000, operable 24 hours a day in temperatures ranging from -10°C to 50°C. This system consists of a portable ground station and a tiltrotor UAV with a total weight of 9.65kg, a wingspan of 1.70m and a fuselage length of 1.56m. HELIADES can endure a load factor of 20g and can pitch and roll at a rate of 60°/s and 150°/s, respectively. At an altitude of 600m, it can fly at a maximum continuous velocity of 70.8m/s and perform an instantaneous turn at a rate of 185°/s. The net launcher of the removal system fires 2x2m reusable nets with biodegradable net shells, while ceramics are used as ammunition for the kinetic cannon. The aerial vehicle itself is manufactured from Polylactic Acid (PLA), a biodegradable plastic produced from renewable resources such as cornstarch. This means that the structure can be 3D printed and results in a sustainable final product. The market price for the complete system is estimated at €200,000, making it competitive with existing products due to its increased maneuverability and autonomy.

In conclusion, HELIADES is a unique and sustainable aerial anti-drone system with an estimated removal success rate of up to 89%, through which it may become a fierce competitor of existing anti-drone solutions.

The group is confident that HELIADES will experience a successful market introduction due to the design’s potential as well as the team’s drive to deliver a sound product.

STARLING 9000 Group 11 Business jets lack the range of big commercial airliners and this creates the demand for an ultra-long range business jet. Starling Corporate Aircraft responds by offering the Starling 9000. It sports a range of 15,700km while still carrying eighteen passengers, thereby delivering unrivalled performance. With an outlook of outperforming any foreseeable competition, state of the art technology is employed.

A

s global wealth continues to increase, air travel is becoming a more integral part of the modern population. Longrange flight capabilities are accessible in most countries with commercial airliners, such as the Boeing 787 with its 15,200km range. For companies and wealthy individuals, business jets are often favorable in terms of travel time, availability and comfort compared to commercial airlines. However, current business jets can only travel up to 13,900km while carrying eight passengers on board. Starling Corporate Aircraft responds to the need for an ultra-long range business jet with the Starling 9000. With a 15,700km range while carrying eighteen passengers, the Starling 9000 delivers un-

matched performance.

A fully carbon composite fuselage and wing reduce the weight of the aircraft compared to that of a conventional structure made out of aluminum. The business jet will be equipped with open rotor engines that have an ultra-high bypass ratio and 25% improved fuel efficiency compared to equivalent performing turbofan engines (A. Breeze-Stringfellow et al., 2013). Aerodynamic improvements include a canard configuration and rudders integrated in the large winglets. This results in a tailless aircraft, which reduces the drag compared to a conventional business jet configuration during cruise. These optimizations strive to extend the range of the

HORUS Group 12 The orrery is a concept as old as humanity itself. Ever since mankind started looking at the night sky, we have tried to map and visualize the vast universe around our own planet. Our neighboring celestial bodies in the solar system have been of particular interest. The first evidence of an orrery is the Ancient Greeks’ Antikythera mechanism, which dates back to 150-100 BC (Freeth, 2006). Over the years, much more sophisticated models of the solar system have been produced, in line with technological advancements. Contemporary technology allows for the next step in orrery design: an orrery consisting of UAVs called HORUS. WHAT IS IN THE NAME? HORUS stands for the Heliocentric ORrery UAV System: an orrery with the Sun at the center. This might seem obvious, but this has not always been the case. The planets are represented by spherical UAVs, which follow the 3D planetary orbit of their particular celestial object. The UAVs will be recognizable as their corresponding planet by their size and their position in the solar system, as

well as by a custom visualization on the shell of the UAV. This visualization is achieved through a coating with a carefully selected color scheme.

INTERACTION & EDUCATION This visualization is very important, since one of the main goals of the system is to educate children in the way the solar system works.

This goal is achieved by building HORUS

Starling 9000 by reducing fuel consumption or increasing fuel capacity. Furthermore, as an innovative company, sustainability plays an important role. This includes designing for low noise, end of life solutions, low emission and lean manufacturing. Implementing the latest technology requires specialized equipment and personnel to guarantee high quality and on time delivery by 2020.

The modular carbon composite design includes structural health monitoring and transparent panels to allow for reduced and quicker maintenance. These improvements also translate to customer advantages in addition to the extended range such as a 10% reduced operational cost compared to the competition and a comparable purchase price of 60 million USD. The cockpit crew can experience the joy of a full glass cockpit, a bed to rest during long flights and many other features. Most importantly, the interior of the Starling 9000 is designed to impress, with maximal passenger comfort. This includes sustainable organic fiber sound insulation, fully reclining spacious seats, a galley, a lavatory with a shower, and a never-seen-before panoramic window, which is four times larger than the standard aircraft window.

A family trip across the globe or an office in the sky with exceptional views is made possible by Starling Corporate Aircraft through revolutionary engineering and the latest technology the industry has to offer. The Starling 9000 is designed as a high value investment, providing reduced travel time and worldwide access to airports with paved landing strips, while offering maximum comfort to the crew and the passengers.

References [1] A. Breeze-Stringfellow et al. Open rotor engine aeroacoustic technology final report.

FAA, May 2013

as an interactive solar system that one may walk through and under. The system has several operational ‘modes’, of which the most important ones are the demonstration and the orbiting modes. The demonstration mode allows a UAV to descend into the hands of a child, who is then able to investigate the ‘planet’ and release it back into its orbit again. The orbiting mode shows the actual movement of the planets.

UAVS The most important piece of HORUS is the UAV. There are four UAV sizes, corresponding to the actual sizes of the planets. Mercury and Mars are the smallest planets, with a diameter of 22cm and a mass of 1.1kg. Venus and Earth are both 30cm and 1.3kg. Next are Uranus and Neptune with 40cm and 1.6kg and of course the biggest UAVs represent Jupiter and Saturn, at 50cm in diameter and with a mass of 2.0kg.

LEONARDO TIMES N°4 2016

35

The structural design is such that any UAV can withstand a fall from 5m. Since safety is paramount, there is a crumple zone installed in the bottom of the UAV to lower the impact forces of a falling UAV. The UAV houses two

propellers providing the required thrust, the CPU, other electrical systems and batteries supplying the necessary power to the propellers and these onboard systems. Furthermore, it is equipped with a soft outer

shell, designed to withstand and dampen low-speed collisions such as charge station docking.

THE GRAND SCHEME OF THINGS Overall, the system consists of eight sets of two identical UAVs, a charging station with sixteen docks, live IR beacons providing the UAVs with their position and one Sun, mounted in the middle of a 10x10x5m flight envelope. There will be one supervisor present during demonstrations and he or she will be on call in order to fix possible system status errors. In short, we believe HORUS can be an amazingly educational system, and a valuable addition to any space exposition or science exhibition, either as a standalone project or in collaboration with other elements.

References [1] Freeth, Tony et al. (30 November 2006).

"Decoding the ancient Greek astronomical calculator known as the Antikythera Mechanism" Nature 444, p. 587-591 (30 November 2006). http://www.nature.com.tudelft.idm. oclc.org/nature/journal/v444/n7119/full/nature05357.html. (Accessed 14-06-2016)

PICS Group 13 In the past years, the size and mass of satellites has shrunk significantly. Smaller and compacter satellites are becoming the industry standards, fueled by ever smaller components from other industries. Femto-satellites (an even smaller weight class below the nano and pico weight class, being less than 100 grams) will form the next class of satellites. This DSE deals with showing the potential of femto-satellites by establishing a concept that will show a promising femto-satellite specific application.

T

he main advantage of using femto-satellites is their cost. They can be built with cheap, off-the-shelf components. Manufacturing costs can be kept low due to their small size. Launch costs are virtually nothing compared to large ones.

Despite having a mass smaller than that of 36

N°4 2016 LEONARDO TIMES

your phone, coming up with potential applications is very easy. They are particularly suitable for missions with a short duration in Low Earth Orbit due to their limited lifetime.

For example: scientific experiments in space, amateur sprites and as a tool for universities/ schools. Swarm applications also show po-

tential, since the costs of launching multiple are relatively low. DSE group 13 has come up with another exciting application: promotion and inspection of a larger host satellite, named the PICS (Promotion Inspection Cubic Satellite) mission.

Let’s focus on the promotion first. A development in the space industry that has gained momentum in the past decade is the use of photographs for promotional purposes. All organizations involved in space have Facebook, LinkedIn and Twitter pages on which they share their progress, updates and beautiful pictures; selfies of astronauts are becoming rather commonplace. The large problem that is currently encountered by these space organizations is that it is impossible to take images of their spacecraft in-orbit while performing its duty. This is why organizations have a reason to integrate the PICS satellite on board their spacecraft. When Rosetta made a selfie, it caused quite a stir. It is likely that the demand for such pictures will only increase in the next few decades as missions gain in complexity.

Continuing with inspection, since the PICS mission will take place in close vicinity of a host spacecraft, the pictures taken can also be used to inspect the state of the host spacecraft. In-orbit satellite inspection is very rare and PICS is the first satellite to achieve this. The PICS mission will focus on inspecting the state of the solar panels and bus, and the effect of micro meteorites and space debris on the spacecraft. Very little knowledge exists about these subjects and existing models are only based on very old statistical data. The pictures taken by the PICS mission

will contribute to updating these models and will help with space debris mapping of objects of a few centimeters.

The femto-satellite is carried with the host spacecraft and deployed from the host spacecraft at a time chosen by the customer. Due to their small mass, it is even possible to stow multiple femto-satellites on a host

spacecraft for periodic deployment over a longer lifetime. After deployment, the femto-satellite orbits around the host spacecraft, takes pictures and sends these to the host.

When it has completed its purpose, it eventually burns up in the atmosphere, preventing further creation of space debris. To accelerate the de-orbiting process the PICS has its own inflatable de-orbiting system.

MATRYOSHKA Group 14 The Venusian atmosphere is quite unique due to the immense size and mostly CO2 composition. Yet, similarly to Earth, it has clouds, however they are made of sulphuric acid, bringing acid rain to a whole new level. Curiously, the sulphuric acid should break down over time, yet the Venusian clouds remain thick and steady over Venus. This indicates that there must be sulphuric influx. A possible explanation is the presence of volcanoes, which leads to our mission statement: to detect recent volcanic activity and characterize eruption products such that sinks and sources can be identified.

V

enus is often called “Earth’s twin sister gone wild”. With a steaming hot surface temperature of 470°C, a crushing surface pressure of ninety times that of the Earth, ravaging winds of 500kph, a dense sulphuric acid cloud layer ranging from 50km to 70km and an acidic haze ranging from 30km to 100km, one is inclined to agree. What tips the scale is the extremely slow retrograde rotation, making the sun rise in the west and set in the east where one Venusian day is 243 Earth days, which is longer than the Venusian year which is 225 Earth days.

Setting aside the madness of Venus, it is important to look at the design space. The thick Venusian clouds may alter or even absorb any long-range observation methods, therefore there is a need to go below the

This study shows the potential of femto-satellites and paves the way for further development of this technology. In the next few decades, satellites will keep getting smaller and smaller, making femto-satellites a logic and an affordable next step in the space industry.

batteries. Due to the slow rotation of Venus, the aircraft will move forward with respect to the solar longitude and drift back during the climb. This means that the aircraft will always be in the sun light and therefore have power.

Accompanying the aircraft is the spacecraft that will first map the Venusian surface to determine possible changes in topography to determine active volcanoes and therefore possible landing sites. Once the mapping phase is over, the spacecraft’s orbit will change to a highly elliptical one to act as a communication relay.

The entry will be performed at a shallow angle of ten degrees. This will allow for a relative benign entry with a maximum acceleration of 55g. Once terminal velocity has been reached at an altitude of 130km, the heatshield is ejected to the side. The aircraft will be deployed soon after. The canard and tail are deployed first since it allows for control and stability, followed by the main wings.

The aircraft will then perform a maneuver to turn right side up.

clouds, below 50km. However, the available solar power greatly diminishes the further down you go due to the clouds, therefore it is preferable to stay above 60km. In addition, once you reach 120°C, any electronics on board will overheat and fail, which happens at 45km. Continuously being in the clouds is also not an option, since they will corrode the vehicle over time.

Exploring all the design options, the most likely design candidate to succeed is an aircraft carrying the lander. The aircraft will stay, depending on wind speeds, between 62km and 75km to charge its batteries for a daring decent. Once fully charged, it will nose-dive down to 32km, perform necessary scientific experiments and possibly release the lander, to then steady climb back up to charge its

ICARUS+ Group 16 The Royal Netherlands Air Force has expressed their interest in having their own space assets for intelligence gathering purposes. Therefore, they have tasked team S16 with the design of a UHF transponder payload that will deploy at a 60km altitude from the Lynx Mark I spacecraft. This will serve as a technical demonstration mission to establish the feasibility of a spacecraft that fits within a 2U space and is optimised for maximum range. The possible applications range from establishing communication networks in hard-to-reach places, to radar jamming, whilst being nearly undetectable by radar.

The aircraft will carry the 90kg lander and release it through its cargo bay doors. It looks much like a flying wing with a thicker mid section which contains the batteries and lander in an insulated environment. The wingspan is 13.5m with a total surface area of 35.6m2.

The lander will be passively stabilized during the decent and due to the thick atmosphere, and hence will not need a parachute to slow down. Using laser spectrometers and infrared cameras, it will be able to survive for two hours before the insulation cannot hold back the heat and the lander fails.

If you have any questions, please do not hesitate to contact us at weinmiller@live.co.uk

T

he outcome of this project is a deployable supersonic glider, aptly named the ICARUS+, as it is always true that whatever goes up must eventually come down. The design is able to autonomously navigating to its target destination without any propulsive means. It uses a compound delta wing-canard configuration, with the canards optimised for supersonic controllability and the wings for subsonic glide. Furthermore, the UHF antenna deploys from the rear LEONARDO TIMES N°4 2016

37

Once the Lynx safely reaches the Mesosphere at 60km altitude, the design will be released from the Lynx. As soon as the ICARUS+ is at a safe distance away from the spacecraft, the UHF antenna will deploy from the back and push the design out of the box. Using an innovative hinge design, the vehicle will be deployed into its final configuration with wings deployed and start its re-entry down to Earth. The low pressure in the high atmospheric environment causes the design to start off with a stabilising fall where it will reach Mach 1.84. When a stable fall is achieved at 40km altitude, the design will pull out and start the horizontal long range flight. The ICARUS+ is able to reach a range of over 230km with a total flight time of around seventy minutes.

Autonomous flights from altitudes above 40km have never been done before, especially not without any means of propulsion.

Moreover, fitting this design into a 2U box and still keeping it within the weight limit of 2kg is quite challenging. Still, solutions have been found to overcome obstacles along the way. This makes the ICARUS+ a one-ofa-kind design and ready to take on the future challenges in research and observation. and offers a half-duplex communication link.

The outer fuselage is made out of 3D-printed titanium with a silica-aerogel heat shield beneath the fuselage. Control is achieved with the use of elevons and canards that are actuated based on the flight data from an internal GPS and IMU sensor. The mission can be divided into four different phases, which include launch, deployment, pull-out and glide.

The launch is performed by the Lynx Mark I, which is a reusable spacecraft developed

by XCOR. The design is safely stored in a 22x10x10cm box in one of the payload bays, which can be found in the back of the Lynx.

This box is not only the interface between the launch vehicle and the design, it also provides reinforcement in order to protect the design from the high loads that occur during launch. Those consist of up to 6g loading and high vibrational stresses.

MAGNUS AEOLUS Group 18 Over the last century, aviation has followed an extraordinary path. It has evolved from the first bare-bones prototypes to being the most iconic mode of transportation. Nowadays, we picture airplanes in a very specific way. Even the so-called “unconventional” configurations are not really unconventional when it comes to providing lift; practically all of them are fixed-wing. But is this the only way to fly?

The ICARUS+ was intended as a technical demonstration mission first and foremost.

However, further research and testing are needed to expand the capabilities of the current design.. The team is confident that it will bring high added value to future research opportunities and enable new solutions to tackle the problems our world and humanity as a whole is facing.

I

n fact: no. An alternative would be to utilize the Magnus effect: the force exerted by the air on a rotating cylinder or sphere, perpendicular to the direction of the freestream and the vector of rotation.

The Magnus effect promises to provide lift coefficients as high as 12; about 5-6 times higher than the conventional modern aircraft. The idea was first explored in aviation during the 1930s, when Anton Flettner, a German aviation engineer and inventor, utilized the Magnus effect to build the first aircraft generating lift using rotating cylinders instead of wings. No record of this aircraft flying (or failing to fly for that matter) was ever published and although a few concepts were proposed later, none of them actually found their way to (detail) design and production phases.

THE MISSION The purpose of this project was to investigate the feasibility of the Magnus effect in aeronautics by designing an aircraft that can fly from Rotterdam-The Hague to London Heathrow airport (350km), in less than ten hours, carrying one passenger and 10kg 38

N°4 2016 LEONARDO TIMES

of stroopwafels (reportedly the only Dutch food allowed abroad) for the Queen. This being a relatively unexplored concept, the design process entailed many significant challenges.

On one hand, conventional aircraft design methods and statistics were only barely applicable to the Aeolus. This means that even basic design parameters had to be redefined. One of the most striking examples would be the Lift-to-Drag ratio as an efficiency indicator, which in this case had to be redefined to include the torque required to operate the rotor that turns the cylinder.

On the other hand, fixed-winged aircraft already have a 100-year old “history”, meaning that aviation technology has been devel-

oped around them and might be suboptimal for an unconventional design such as the Aeolus. Therefore, for this concept to work, investigating cutting-edge solutions that are still at an experimental/prototype phase -some of which were not even intended for use in aviation- was an integral element of the design philosophy.

THE DESIGN The Aeolus uses a canard configuration, meaning that the control surface can remain fully effective and unaffected by the (significant) downwash caused by the cylinder.

The cylinder, which has a radius of 27 centimeters and a span of 4.2 meters, is situated at the back of the aircraft at a distance of 1.3 meters above the fuselage. The aircraft is propelled by means of a double ducted fan

MIRU Group 10 MIRU is designed to aid air safety investigators by facilitating a faster and lower cost investigation. MIRU will do so by locating the accident site, coarse mapping and detailed mapping the site, and by performing a toxins detection.

Often an aircraft crashes in remote areas that are hard to reach for investigators. Not only does this delay the investigation process, but also the costs of reaching the accident site and performing the investigation there, run rather high. MIRU is multi-configurable and deployable, such that it can fit in a backpack, and weighs no more than 2.5kg in its heaviest configuration.

W

hen an air accident site is not easily accessible, MIRU will fly to the site, make a coarse map, and returns to the basecamp. When an aircraft has crashed, it may occur that fluids from its cargo have leaked, meaning that toxins may have come free or that there is a risk of explosion. Thus, it is crucial to know whether it is safe for investigators to perform the investigation before they arrive to the site. In this case MIRU comes to the rescue by gener-

ating the coarse map and also performing a toxins screening with its dedicated sensors.

Since every flight has a registered cargo list, it can be known for which toxins one must search for, thus a more specific toxins investigation can be performed. If it is safe for specialists to perform the investigation on site, they will move to the crash site. Having the already prepared coarse map at hand, the specialists will know exactly where to search for the wreckage and what the severity of

providing nearly193 horsepower.

Proving that the potential of the Magnus effect was higher than expected when setting up the project, the final design is able to fly with a maximum take-off weight of 1030kg, carrying two passengers and 20kg of payload up to a range of 740km in less than 5.5 hours (cruise speed of 144km/h). This design proves that the conventional way is not the only way of flying and that other methods could open doors to an alternative future for aviation.

References [1] Seifert, J. (2012). A review of the Magnus effect in aeronautics. Progress in Aerospace Sciences, 55, 17-45.

the crash is. Now, MIRU will aid the air safety investigators by generating a detailed map of the air accident site, such that the investigators have a detailed, aerial overview of the crash site. MIRU is even capable of mapping the area such that a 3D map can be generated, post-processing of the images.

One may think, how can a single UAV perform all these different mission objectives? MIRU answers all your questions: it is multi-configurable. MIRU is a tailsitter in its fullest form, meaning: a flying wing with vertical stabilizers, four vertical and one horizontal flight propellers. When the main purpose is to perform coarse mapping, this configuration is not optimal, thus MIRU will change its platform to a flying wing without the vertical stabilizers and using solely the horizontal flight propeller. In this way, MIRU performs a longer range, higher endurance flight (100min) and can be optimally used for coarse mapping. When MIRU needs to generate a detailed map of the crash site, MIRU needs to decelerate drastically in order to get correct resolution images. MIRU’s velocity must then decrease from a coarse mapping cruise speed of approximately 26 m/s to 4.4m/s. In this case, MIRU cannot continue in its flying wing configuration since decelerating to this airspeed will result in stall. Thus, MIRU gets rid of its wings, remaining only with its body, but now the four stabilizers are installed again, together with the four vertical flight propellers. In this configuration, MIRU is able to generate a highly detailed map of up to 400 pixels per meter, when flying at an altitude of 5m. Lastly, MIRU can be configured in a hybrid form: the tailsitter with vertical stabilizers, the four vertical flight propellers and one horizontal flight propeller. MIRU is used in this form when both horizontal and vertical flight are needed, which is the case when toxins detection must be performed in combination with coarse mapping in a remote area. MIRU is also used in this form when a vertical take-off is needed due to limited take off space in remote areas.

LEONARDO TIMES N°4 2016

39

VOLVO

INTERNSHIP

INTERNSHIP AT VOLVO CAR CORPORATION Aerospace Engineering in the Automotive Industry Robert Regtuit, MSc Student Aerospace Engineering, TU Delft The Volvo Car Corporation is one of the biggest car manufacturers in the world. As an intern, my task was to assist the team that was responsible for the first series of cars that could drive autonomously around the ring of Gothenburg in Sweden. crease the safety in everyday traffic scenarios. When using these systems, the driver is still responsible for driving the car, but in some situations those assisting systems will overrule the driver. An example of such a system is the auto-brake system, which will brake if the driver fails to act upon the ex-

To do so, a new so-called Drive Me project has started within the active safety department. Drive Me is a pilot program, which aims VOLVO

S

afety has always been a core value in Volvo’s car development. Important innovations range from the three-point safety belt, to the crumple zones in the front and rear of the car, and the recently developed pedestrian airbag. Though safety innovations do not stop there. The board of Volvo has set the vision that from 2020 onwards, fatalities nor severe injuries should occur to people who travel in a new Volvo car.

tremely slow driving car in front of him. Since Volvo wants to cut the human completely out of the loop in the future, those systems are not sufficient, since they function only with a human in the loop. Therefore, new systems have to be developed such that the human is pushed back into being soley a supervisor.

Volvo’s studies have shown that over 95 % of the accidents occuring in traffic are due to human error and can be avoided by automating driving tasks. Volvo believes that in order to avoid fatalities and serious injuries to passengers in their vehicles, it is necessary to completely remove the human out of the driving loop. This means that the driver will be a supervisor and will only have to take over control in the event of unforeseen circumstances, or non-ideal driving conditions such as during extreme weather.

Over the years the active safety department of the Volvo Car Corporation has developed many driver-assisting tools in order to in40

N°4 2016 LEONARDO TIMES

The display as seen by the driver during autonomous diving.

In the Volvo headquarters in Gothenburg, more than 400 people are working on the autonomous driving functionality of the project. Since it is the first time that any car manufacturer aims for full autonomous driving, a lot of challenges have to be overcome. From sensor development to driving strategy, all the way to the lower level control algorithms, everything has to be done for the first time.

Data from radars, cameras, lasers and ultra-sonic sensors are combined to create an overview of the surrounding environment.

The car will be able to distinguish obstacles, other cars and road signs and adapt its driving strategy based on those factors.

In case of a failure, the car is equipped with sensors to guide the car to a safe location.

This fail-safe is required if sensor-failure occurs or in the event of severe weather.

In such an event, the driver is first asked to take over the driving. If the driver does not respond to any of the requests, the car will go to safe-mode, meaning it will try to safely park the car.

In nominal driving conditions, the car will be expected to perform tasks that are routine to human drivers such as plan the route from A to B, change lane when needed and adapt to surrounding traffic.

Most of these functions already exist as separate systems, but in order to drive autonomously they have to be combined into one system. Nowadays, navigation systems already take part in planning the route from A to B and advanced driving systems such as adaptive cruise control are already present in the latest cars. The missing link however is still in the lateral control of the cars. So far, no manufacturer has developed a system that can safely change lanes in operating conditions.

During the internship the main focus was on how to handle these lane changes. Due to the novelty of the technology, no clear guidelines exist. How much distance is the car expected to take? How much accelera-

VOLVO

to create one hundred cars that can drive autonomously on the ring around Gothenburg, Sweden. These cars will be sold to one hundred customers by 2018. The "driver" can read a newspaper or check his phone during the ride around the Gothenburg ring.

The car will take care of maintaining distance to cars in front, whilst planning the fastest route to a certain destination and changing driving lanes if required. Drive Me is a joint project with local authorities, meaning that apart from the teams at Volvo working on the technical development, other teams from different organizations work on legislation proposals. When the cars are released on the actual road, traffic services will analyze how the autonomous cars affect the traffic flow and how autonomous driving could influence the future traffic flows.

Combined information from radars, cameras, lasers and ultra-sonic sensors is used to identify objects around the autonomous vehicle. tion may the car attain? How long after signaling can the car move to another lane?

When human drivers do those things they base it on feeling, but what about a car?

Those features are important in the design, not only due to safety concerns, but also for other drivers to understand what the autonomous car is doing.

Another big difference with aerospace problems is that autonomous vehicles interfere with human-controlled vehicles. All vehicles on the road contribute to the traffic safety. It is therefore important that the driving behavior of the autonomous vehicle is similar to human behavior, to make sure other road users do understand the car as well.

One of the biggest challenges has been to make the car work in “all traffic� scenarios. Unless the car can handle (almost) every traffic scenario, it cannot be used autonomously. If the driver has to take-over frequently, there is no difference to the current driver supporting systems.

The automotive industry definitely offers good opportunities for aerospace engineers.

Car driving is becoming more automated and at the same time other departments are busy reducing the emissions of the car, by increasing aerodynamic and structural efficiency.

How does the car change lanes when there is free space available? Should it just move like most humans do, possibly requiring the car in the other lane to brake? Is it acceptable if an autonomous car makes that decision?

How should the car handle merging in on the highway from an on-ramp, when it cannot find space? Should it stop on the onramp? Or should it continue driving onto the shoulder, until the car spots an opportunity to merge in on the highway? The latter solution is probably safer than the first one, however legislation does not allow such maneuverers.

In the future, driving a car will be more like pilots flying airplanes. This not only requires smart control solutions, but also good display design. If the driver is not in direct control over his car anymore, he is expected to supervise the driving; similar to how a commercial pilot supervises his aircraft during cruise flight.

Considerations like these made the Drive Me project completely different from most aerospace problems. The aerospace industry is already a highly automated and regulated industry, where it is strictly defined what is allowed for and expected from automation.

For me personally, the internship has been an exciting experience. Due to its short development cycles, the development functionalities are tested within weeks. It was really interesting to see that improvements in a simulated environment resulted in improvements in an actual car.

The aerospace industry has plenty of experience in the domain of automated systems and supervisory control; so aerospace engineers have good career opportunities in the automotive industry.

LEONARDO TIMES N°4 2016

41

NASA

FPP

CARBON FLYING Aviation’s contribution to global warming Nithin Rao, Editor Leonardo Times Since 1990, the greenhouse gas emissions due to aviation in the EU have increased by 87% and account for nearly 3% of the total EU greenhouse gas emissions. How dangerous are the effects? What are the problems for new propulsion technologies? And how are such problems tackled to ensure a more sustainable future?

this theory to explain the ice ages and formulated the greenhouse law, an equivalent formulation that is still used today.

THE ROOTS AND REALITY

“If the quantity of carbonic acid [CO2] increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression.”

Claude Pouillet in 1827 and 1838 first showed evidence to support this effect, which was experimentally proved later on

by John Tyndall (1859). The name “greenhouse effect” was coined (wrongly) by Nils Gustaf Ekholm(1901) to describe this effect, 42

N°4 2016 LEONARDO TIMES

though this is not the principle on which a greenhouse works. Svante Arrhenius (1896), a Swedish scientist, is considered the pioneer, as he was the first to develop a theory to calculate the change in surface temperature of a planet with the change in levels of carbon dioxide in its atmosphere. He used

In the above equation, C is the carbon dioxide concentration in ppm (Parts per million).

NASA

The concept of the greenhouse effect in our modern world has largely negative associations. However, just like gravity, it is a natural occurrence. It is the phenomenon by which the temperature of the Earth is maintained. Radiatively active gases, also known as greenhouse gases, absorb and emit radiation. The presence of these gases in the Earth’s atmosphere means solar radiation is absorbed and radiated in all directions, and therefore part of it is also directed towards the surface. The latter is then reflected back into the atmosphere and the process of absorption and emission by the greenhouse gasses repeats, thus trapping the radiation (heat) between the surface and the atmosphere.

This maintains the Earth’s surface temperature. Water vapor, carbon dioxide, methane, ozone and nitrous oxide are all greenhouse gases in the Earth’s atmosphere, without which the temperature on the planet would be around -18°C.

ΔF = α ln (C/C0)

Figure 1 - Global temperature anomaly over the past century.

Figure 2 - Global CO2 concentrations over the past decades. to the planet.

MAJOR CONTRIBUTORS Based on data from IPCC 2014, as seen from Figure 3, electricity and heat production are the major contributors of greenhouse gasses. Nevertheless, transportation also has its share with a contribution totalling nearly 34%, meaning the impact of aviation is 3% to the total CO2 emissions. This value may seem very minimal at first glance, but there are two factors that make us believe otherwise. First, the projected growth of global air travel in the next decade is huge: estimated at 3.8% annual growth. China, USA and India top the list of the demand. This leads to a projected stake of 5% of aviation’s contribution to global CO2 emissions by 2050, which

is a 300% increase from the current level.

Second, the innovation of propulsion systems has reached an asymptote and it’s high time to develop more efficient and cleaner propulsion systems, just like other means of transport have adopted.

THE SCENARIO Why is there a stunted growth in this sector one might ask? Cars have reduced their emissions by 98% and increased their efficiency by 98% as seen in Figure 4, but why has the aircraft industry not adopted this in the past decade? The regulations for automobile emissions are stringent and often revised as soon as a new greener technology rolls out. For example, the EU law states that new cars registered after 2015 must not emit EPA

Arrhenius also predicted that the change in the carbon levels in the future would be human induced, and if un-regulated, the burning of fossil fuels would cause the imbalance. Nonetheless, his theory was rebuked by scientists and the general public, as there was no strong scientific backing to his prediction. This opinion has changed over the past decades due to the evident research and scientists today believe that though carbon dioxide is not the only contributor to global warming, it indeed plays a major role in regulating the effects. This increase in the Earth’s average surface temperature due to the rising levels of greenhouse gases is what is termed as global warming. What are the effects of the rising temperatures? The question is indeed genuine as a bright summer’s day is the best thing that could happen.

There are three main problems. The first is that the tropical regions would be hotter and this is equivalent or even worse than harsh winters, causing more human deaths. In 2015, a heat wave in India resulted in 2,500 fatalities. The second fact is that the melting of the polar ice caps causes a global rise in sea levels. Some countries, such as the Netherlands, are already below sea level and have walls and dams to protect the coasts against flooding. In spite of technological possibilities, economically weak countries or countries with very large coastlines would find it a challenge to save their coasts. There is an indicated sea level rise of 0.12 inches per year since 1992. A few weeks ago, it was discovered that a massive chunk of the Antarctic ice shelf, Larsen C (half the size of Iceland), had it’s fracture grow by 22km. It’s only a matter of time before Larsen C breaks free, causing a rise in the sea level. The third argument is that a change in global temperature would cause a large impact on our ecosystem. The arctic species would soon be extinct and indigenous species, which cannot migrate, would soon be extinct due to this induced climate change. Nearly a quarter of the Great Barrier Reef is dead due to global warming. Similar effects are projected on crop yield and livestock in the coming years, if the temperature rise continues. Hence, human induced CO2 levels are indeed a threat

NASA

C0 is the baseline carbon dioxide concentration and ΔF is the radiative forcing. Alpha is a constant value (five or seven). Based on the CO2 levels at that time, Arrhenius calculated a four to five °C decrease in temperature (in the arctic) for a 0.62-0.55 reduction of CO2 and an increase of eight to nine °C (in the arctic) with a two-and-a-half to three times increase in atmospheric CO2 levels. However, Arrhenius’s predictions are not quantitatively accurate, as the secondary effects such as the influence of carbon change on other natural phenomena such as oceans are not taken into account. Yet, upon analyzing the plots in Figure 1 and Figure 2 depicting the carbon content in the atmosphere and the temperature rise, the basic theory is hard to criticize.

Figure 3 - Global greenhouse gas emissions by economic sectors in 2015.

LEONARDO TIMES N°4 2016

43

EPA

nology in aviation. The anomaly of the gas prices and various concerns of the national and international green organizations have yet lead the aircraft industry to continuously aim for a fuel efficient design. For example, the Boeing 787 and Airbus A380 are 35% more fuel efficient than the aircraft in 1975 (Figure 5).

TECHNOLOGICAL CONSTRAINTS

Figure 4 - Efficiency increase of automobiles over the past decades. “technology forcing” method is considered unfit for aviation, and any technology is not certified unless it is tested rigorously for safety and reliability. This restricts the use of new technology within a few years of development in aircraft, giving safety the highest priority. Furthermore, there is no national or international regulation for greenhouse gas emission of an aircraft besides the EU ETS (European Union Emission Trading Scheme). EU ETS works by allocating emission caps to each operator for flights within the EU. If the emission limit is reached, allowances must be procured through purchase or auction. International flights are exempted, however, from EU ETS. Lack of similar international taxation and log of airline fuel consumption may also be one of the reasons for the lack of development of cleaner tech-

This is the limiting factor from a technological perspective in a nutshell. To create an all-electric green aircraft, powered by batteries or fuel cells, higher weight and volume are demanded by the greener fuels in order to deliver the same amount of energy. This IEA

more than 130g/l of CO2. The current emission standards for aircraft engines were set in 1996, and new standards go into effect to engines entering service from 2004 (Nox emissions reduced by 16%). Unlike a car, which is a land-based vehicle, an aircraft is fundamentally dangerous and expensive to experiment on and to innovate. Any airworthy vehicle must pass the strict standards of safety and reliability, set by the ICAO (International Civil Aviation Organization). For example, in a car, if the engine fails, one has to pull over and turn the hazard lights on, until help arrives. Per contra, in an aircraft, the failure of an engine is one of the worst nightmares as it leads to devastating consequences, putting the lives of all the passengers in jeopardy.

There are just 10 incidents of a commercial aircraft engine failure since 1975. Hence, a

It's not only the lack of regulations that has curbed innovation. The main hurdle is the power to weight ratio. The power-to-weight ratio of the energy converter along with the energy to mass and energy-to-volume ratio of the fuel is what decides the reality of a power plant application in an aircraft. As seen from the Figure 6, kerosene produces 35MJ per liter and around 50MJ of energy per kg.

On the contrary, a Li-ion battery produces 2 MJ of energy per liter and nearly 1MJ of energy per kg. This means a 50kg Li-ion battery will produce the equivalent energy as a kg of kerosene will or 17.5 liters of Li-ion is required to produce the energy equivalent to one liter of kerosene. This energy is converted to work by energy to work converters such as IC (internal combustion) engines, motors and fuel cells. Present day aircraft are mostly powered by IC engines such as the fourstroke engine and the gas turbine. From Figure 7, it can be seen that gas turbines have the highest power-to-weight ratio, followed by the electric motor. Yet, due to the high-energy capacity of the kerosene, a four-stroke engine is the next choice for propulsion in aircraft.

Figure 5 - Energy intensity decrease of aircraft over the past decades.

44

N°4 2016 LEONARDO TIMES

would mean a higher weight of the structure and propulsion system, thus reducing the payload capacity to almost a few percent of the overall aircraft weight. With the current technology, this is almost limited to UAVs and gliders. Regardless, an optimized manned aircraft design with state-of-the-art technology would result in an aircraft similar to the one seen in Figure 8. The Solar Impulse 2 gave us hope that an all-electric aircraft is not far away. The technological breakthrough of the Solar Impulse 2 indeed paves way to electric powered light sport aircraft but this is far beyond reality for an all-electric passenger aircraft. Hence, a rigorous shift of the propulsion system of civil aircraft is unforeseeable in the near future.

Yet this doesn’t eradicate the options for an alternative. The key is to develop hybrid propulsion systems and fuels with lower emissions, and nearly equal power-to-weight and power-to-volume ratios, than to dream of jumping curves in the propulsion technology of aircraft. High priority must be given to develop these promising alternate technologies, rather than investing all the resources in an all-electric power plant. The shift to hybrid propulsion systems is more realistic than to wait in vain and continue the emissions until a new power storage technology emerges.

Figure 6 - Energy densities of various energy sources.

THE PRESENT EFFORTS The possibility of hybrid propulsion has been realized by a lot of organizations in the EU and in the U.S.. Major projects in the U.S., which are developing hybrid propulsion systems, are NASA’s Advanced Air Transport Technology project and the SUGAR project by the Boeing-NASA collaboration. In the EU, Airbus and Rolls Royce are working together on the Distributed Electrical Aerospace Propulsion Project (DEAP Project). Advanced Hybrid Engines for Aircraft Development (AHEAD) is another major project in the EU, with extensive collaboration between TU Delft, DLR and a few other prime universities in Europe, which aims to develop hybrid engine concepts. The common goal of all these projects is to create a reliable propulsion system for aircraft, with effectively reduced emissions.

References Figure 7 - Power to weight ratios of different energy to work converters.

SOLAR IMPULSE

[1] www.avstop.com [2] www.nasa.gov [3] www.iata.org [4] www.aviationbenefits.org [5] www.unfcc.int [6] www.epa.gov [7] www.ec.europa.eu [8] www.machinedesign.com [9] www.ahead-euproject.eu [10] www.info.solarimpulse.com [11] www.oceanservice.noaa.gov [12] www.nationalgeographic.com [13] www.theguardian.com [14] www. epa.gov [15] www.hfw.com [16] www.wikipedia.org [17] www.ec.europa.eu

Figure 8 - Solar Impulse 2 - Long range solar power experimental aircraft by the Swiss.

LEONARDO TIMES N°4 2016

45

LINEAR STABILITY OF PERIODIC LAGRANGE ORBITS IN THE ER3BP

Investigation at L1/L2 in the Earth-Moon system

DAVID A. KRING

SPACE ENGINEERING

Lotfi Massarweh, MSc student Aerospace Engineering, TU Delft

The 3-Body Problem has been studied for more than 300 years. While periodic solutions are known to exist within the “Restricted Problem”, no general solution is yet available. In this research, the existence of bifurcations in the periodic solutions’ linear stability behavior has been investigated, looking at three different families of orbits around two equilibrium points of the system.

S

ince the launch of Sputnik-1 in 1957, the first artificial Earth satellite, the motion around celestial bodies has been described by the Kepler solution of the 2-Body Problem. When considering three bodies under their mutual gravitational attraction, the model better approximates the real physical dynamics, although many difficulties arise and no analytic solution is available. It follows the definition of a “restricted problem”, where the third mass (e.g., the spacecraft) is assumed many orders smaller than the others (e.g., planets or moons), thereby not influencing their relative Kepler 46

N°4 2016 LEONARDO TIMES

orbital motion. Depending on such bounded motion, we are able to provide two different formulations: a Circular and an Elliptic problem. In this work, both models have been considered, later exploiting bifurcations in what is defined as “linear stability” for some particular orbits.

Both previous models admit five equilibrium points (Figure 1), named Lagrange points or L-points in general literature [1], where L1-L2-L3 are defined as collinear since they are located along the syzygy (straight line connecting the two masses

M1, M2). Concerning L4-L5, they are referred to as triangular points, as their specific locations are at the vertices of an equilateral triangle in a co-rotating frame (called synodic). Collinear points are known to be linearly unstable for any 3-Body system, while bounded trajectories can still exist in a neighborhood and have been employed for space scientific missions. In the last forty years, since the launch of the International Sun-Earth Explorer-3 (ISEE-3), many other satellites have successfully operated near L1-L2 in both the Earth-Moon and the SunEarth system. Advantages of such locations become evident when considering space communication or observational purposes, while higher costs are usually involved for reaching other L-points. One of the most important factors in a realistic space mission design is the assessment of the stabil-

LOTFI MASSARWEH LOTFI MASSARWEH

Figure 1 - The Earth-Moon system given in a synodic frame that is co-rotating with both main masses. All five Lagrange points are shown in magenta, with the three collinear lying along the syzygy direction and two triangular at the vertices of equilateral triangles.

Figure 2 - Single members shown from all three families of periodic solutions found near L1-L2 points (magenta) in the Earth-Moon system. The synodic frame is adimensionalize respect to the Earth-Moon distance, while the origin has fixed at the barycentre of the system. ity for some specific solutions, where more stable trajectories obviously allow reducing station-keeping costs for corrective maneuvers [2-3]. The Earth-Moon-Satellite configuration has been adopted here only as a test-case, while similar methodologies can be easily extended for many other celestial

systems, as long as all main assumptions remain valid.

The research topic investigated here aims to extensively characterize both the two aforementioned models, thus developing a systematic procedure able to analyze

several families of periodic orbits that exist around each Lagrange point. At the same time, trajectories found in the Circular Restricted 3-Body Problem (CR3BP) need to be examined with more complete dynamics, even though difficulties arise in their mathematical expression. However, the Elliptic problem (or ER3BP) is expected to be a more accurate model since the orbital motion of planets in the solar system is indeed better described by elliptic trajectories [4]. From this perspective, the dependence upon the continuous parameter “e”, the nominal eccentricity of the main Kepler orbit, becomes very important. This positive parameter is always defined as smaller than one for the elliptic case, while equal to zero in the circular case.

Considering the CR3BP, the Dynamical System Theory (DST) introduced by J.H. Poincaré (1854-1912) in “Les Méthodes Nouvelles de la Mécanique Céleste” indeed represents a fundamental tool for an extensive analysis of the model. The objective of his work was “to provide a geometrical study of the solution curves of a first-order differential equation”, and indeed it was his geometrical insight which became one of the hallmarks of his work on differential equations [5]. Above all, his results, periodic solutions in the Circular Problem are known to always be enclosed within continuous families, while in Figure 2 only single members have been shown, based on the same energy levels. It is trivial to understand that the linear stability can actually change along each family, moving from one member to another, while such different behavior is usually related to so-called bifurcation points [6].

The investigation on the linear stability and its bifurcations consists of a combination between two different approaches: an analytic one based on the Lindstedt-Poincaré method and a second one, based on a numerical scheme. The first method is part of a more general perturbation theory, aiming to find an analytic approximation of periodic solutions when considering small amplitudes around each equilibrium point.

Unfortunately, such an approximation cannot really be used for a robust examination of stability since it is defined by a truncated LEONARDO TIMES N°4 2016

47

LOTFI MASSARWEH

Figure 3 - The Differential-Correction algorithm (LEFT) is shown based on a small displacement dynamics linearized with respect to a nominal trajectory. It is later applied on the xz-plane of symmetry (RIGHT) in order to correct a first guess obtained from the analytic approximation.

The DC-algorithm, which is the first step of the numeric approach, is shown in Figure 3, where displacements from the nominal trajectory are related by a linearized relation, such that introducing Φ(tf,t0), also called State Transition Matrix (STM), we arrive at

having X=X(t) as state-vector of the differential system and Φ(tf;X0 ) as general solution at t=tf with X(t0 )=X0. When neglecting higher order terms as O(|δX0|2 ), the previous expression properly describes the linear relation between an initial and a final displacement, here defined by δX(t0) and δX(tf). In a very similar way it is also possible to investigate the linear stability of T-periodic solutions, thus making use of what it is called Monodromy matrix. The latter is simply an STM evaluated over an entire period T, while the examination of its eigenvalues 48

N°4 2016 LEONARDO TIMES

provides an accurate characterization of the local dynamics. Successive step in this process involves the generation of a new guess for each additional member of the same family, where at least one of the three main shooting parameters needs to be changed (e.g., the position along the x-direction). The latter, based on the Numerical Continuation technique [8], employs the two solutions previously generated, thereby assuring a sufficiently good estimate for each next orbit, reducing the number of iterations necessary for the correction.

Bifurcations along each continuous family can be found at specific members where the linear stability behavior is actually varying. This analysis of the local dynamics is able to show the existence of stable/unstable directions (also called manifolds), along with quasi-periodic trajectories or also additional families that are surrounding specific orbits for each family initially investigated.

Once the study of the circular model has been completed, the very same procedure can be extended also for the elliptic model,

where the eccentricity parameter is no longer zero and the entire differential system is directly dependent upon the θ-variable. This last variable represents a relative phase of the Kepler motion for both the main masses and it has been adopted as the new timelike parameter for the differential system. In this way, by means of a time-rescaling technique [9], all quantities refer to the θ-phase, which also defines the rotation rate of the synodic frame, but is now no longer uniform as seen for the circular case.

A very notable aspect is that all the symmetries still hold in the new model, as do all five L-points, whereas the direct θ-dependence introduces an additional constraint on suitable shooting conditions for periodic solutions. In the ER3BP those particular trajectories can still be found, but their orbital period TE requires being in resonance with the one of the M1-M2 system (2π-periodic), while starting with the CR3BP their period TC can be expressed as:

LOTFI MASSARWEH

Taylor expansion of the dynamics around the L-point. It follows that the approximation becomes only a first guess to initiate the numerical algorithm, which aims to later correct such a predicted solution. De facto, this entire procedure exploits particular symmetries of the differential system considered, where it is known that periodic solutions require crossing the xz-plane orthogonally [7]. Starting within this plane of symmetry, initial conditions (or shooting conditions) can be decreased from six (3 positions + 3 velocity components) to only three variables. Hence, each periodic solution can be fully characterized by an initial x/z-position and a precise shooting velocity orthogonal to the xz-plane, therefore along the y-direction. Two steps define the numeric approach: first, the Differential-Correction algorithm (or DC-algorithm) corrects an initial guess previously found, while additional members can be later generated based on the Numerical Continuation technique (NC-technique).

Figure 4 - The Halo M2N1-resonance at the L2 point is represented for the Earth-Moon system in both rotating (LEFT) and inertial (RIGHT) reference frames. Main masses and the L-points are shown, while in the LEGEND more details have been given for the colour-notation adopted.

LOTFI MASSARWEH

Figure 4 - The two branches bifurcated from a Halo M2N1-resonance orbit at L2 are shown in the co-rotating frame with its projections (in grey). The initial orbit (in blue) leads to both Apo-Halo (LEFT) and Peri-Halo (RIGHT) families, while L-points and main masses are now no more fixed. with N and M as the number of systems and orbital revolutions respectively. Starting with one of the three families studied, it can be observed that the continuous character is lost, while an infinite set of possible combinations {M,N}i leads to infinite possible periodic orbits, embedded in discrete families.

A brief example of a Halo M2N1-resonance at L2 has been given in Figure 4, where both the co-rotating and the inertial frame have been considered, along with both masses M1-M2, the small spacecraft P3 and the L2point in the Earth-Moon system.

At this point, suitable resonance orbits in the CR3BP (for e=0) are first selected and then propagated in the Elliptic problem given e∈(0,1). A precise step-size is chosen to be Δe=10-4, in this way slowly increasing the eccentricity from zero till a nominal value, where eEM= 0.0549 has been used for the Earth-Moon case. At each step the initial guess is corrected by the DC-algorithm,

“

eter, where different shooting times actually lead to different solutions, as opposed to what has been observed for the circular case. Each one of these two branches can be fully investigated for any eccentricity value, as long as the Kepler motion remains bounded, thus for e<1.

The most important consequence of what is called eccentricity-bifurcation (at e≅0) becomes the possible different behavior of the local dynamics, mostly dependent upon the branch considered, as meanwhile the orbit’s geometry itself is also changing.

In fact, this last difference can be clearly seen in Figure 5, based on a co-rotating synodic frame and starting again with the Halo M2N1-resonance at L2. Clearly, the position of all Lagrange points changes in time within such as a reference system since also the relative distance of both masses with respect to their barycentre (origin of the frame) is no longer constant

Sir Isaac established the rules, Poincaré presented the challenges - Szebehely, Victor G. “The Few Body Problem”, 1987

but now taking into account what has been defined as Ellipticity Periodicity Condition [10]. The latter involves initial conditions within the xz-plane, where it is also required to start at a specific phase such that θ=0 or θ=π, therefore when both main masses are respectively at their peri- or apo-apsis within the Kepler elliptic orbit. Hence, two different branches arise at e≅0, each from a single resonance solution, depending on what can be treated indeed as a new time-constrain on shooting conditions. In the ER3BP, periodic solutions are no more related by continuous proprieties, for example when considering changes in linear stability between two successive members of the same family. Due to this separation in the two branches, it follows that the eccentricity here becomes the main bifurcation-param-

”

in time. As a main consequence of this bifurcation, the different behavior of the local stability in the ER3BP depends mostly on the shooting time θ0 chosen, along with the nominal eccentricity value selected for the system. These features need to be considered in practical mission designs, where a different choice for the θ0-value can significantly affect the local stability behavior and so also the relative mission costs, e.g. for the necessary correcting maneuvers. Most importantly, the entire investigation presented here has provided a robust procedure with the potential ability to analyze many other families, along with other different L-points.

Furthermore, no limitations exist on a possible application of the very same methodologies for other 3-Body systems, e.g. in binary systems where the mass-ratio between

M2 and M1 is much larger than the one relative to the Earth-Moon case.

If you have further ideas or want to contribute to this research as a graduate student, you can check the thesis work on the TU Delft repository, or contact the author for further information by email leotimes-vsv@ student.tudelft.nl References [1] Szebehely, V. G. (1967), “Theory of orbits, the restricted problem of three bodies”.

New York: Academic Press.

[2] Gómez, G., Llibre, J., Martínez, R., Simó, C. (2001a), “Dynamics and mission design near libration points. The case of collinear libration points”, Vol. I. Singapore; River Edge, NJ: World Scientific.

[3] Gómez, G., Llibre, J., Martínez, R., Simó, C. (2001b), “Dynamics and mission design near libration points. The case of triangular libration points”, Vol. II. Singapore; River Edge, NJ: World Scientific.

[4] Musielak, Z. E., & Quarles, B. (2014), “The three-body problem”. Reports on Progress in Physics, 77(6), 065901.

[5] Barrow-Green, J. (1997), “Poincaré and the Three Body Problem”. London: London Mathematical Society, American Mathematical Society, Providence.

[6] Howell, K. C., & Campbell, E. T. (1999), “Three-dimensional periodic solutions that bifurcate from halo families in the circular restricted three-body problem”. Spaceflight Mechanics 1999, Vol 102, Pts I and Ii, 102, 891-910.

[7] Miele, A. (2010), “Revisit of the Theorem of Image Trajectories in the Earth-Moon Space”, Journal of Optimization Theory and Applications, 147(3), 483-490.

[8] Hénon, M. (1969), “Numerical exploration of the restricted problem”, V. Astronomy and Astrophysics, 1, 223-238 [9] Verhulst, F. (2000), “Nonlinear differential equations and dynamical systems”. Berlin: Springer.

[10] Campagnola, S., Lot, M., & Newton, P. (2008), “Subregions of motion and elliptic halo orbits in the elliptic restricted threebody problem”. Advances in the Astronautical Sciences.

LEONARDO TIMES N°4 2016

49

ASML

ASML: BE PART OF PROGRESS USB-sticks van 16 Gigabyte liggen nu voor nog geen tien Euro bij de supermarkt. Niet iets waar je vaak over nadenkt, maar ondertussen is het een prestatie van wereldformaat. Mogen we je even meenemen in de wereld van Moore’s Law? Oftewel de hoog-complexe omgeving waar bedrijven wereldwijd bijna jaarlijks (en tegen een enorme inspanning) een verdubbeling van de capaciteit van chips realiseren. Waar technologische doorbraken bij voorkeur enkele nanometers klein zijn. En waarvan één van de belangrijkste spelers in Nederland, om precies te zijn in Veldhoven, staat.

CRUCIALE STAP Welkom bij ASML, fabrikant van lithografiemachines voor de productie van computerchips. ASML levert haar apparatuur aan alle grote chipproducenten ter wereld, waaronder Samsung, Intel en TSMC. Van de dozijn productiestappen om tot een chip te komen, vult ASML er maar één in, maar wel een hele cruciale. Lithografie omvat het belichten en chemisch etsen van wafers om de onderdelen op de chip te ‘printen’. Daarmee is het haalbare formaat compleet afhankelijk van de nauwkeurigheid in het lithografieproces. Met de laatste generatie machines van ASML kun je lijnen printen op een chip van circa 20 nanometer dun. Dat komt op hetzelfde neer als het printen van een complete roman van 500 pagina’s op 1 centimeter van een menselijke haar!

COMPLEX SAMENSPEL Je kunt je voorstellen dat de machines van ASML bijzonder complexe systemen zijn.

50

N°4 2016 LEONARDO TIMES

Dagelijks werken duizenden ingenieurs en researchers aan de verdere ontwikkeling van deze machines. Want de Wet van Moore is onverbiddelijk. Gestuurd door de moordende concurrentie op de hightech markt, moeten chips alsmaar kleiner, sneller en goedkoper. De technologische race tegen de klok maakt het werk bij ASML veeleisend én uiterst fascinerend. State-fo-the-art fijnmechanica, dynamica, optica, elektronica en informatietechnologie vormen een geavanceerd samenspel en leveren steeds weer systemen op die betrouwbaarder, sneller en nauwkeuriger zijn dan hun voorgangers.

STUWENDE KRACHT De stuwende kracht achter de technologische doorbraken van ASML zijn ingenieurs die vooruit denken. De medewerkers van ASML behoren dan ook tot de creatiefste denkers in de natuurkunde, wiskunde, scheikunde, mechatronica, optica en informatica. En omdat ASML jaarlijks ruim een

miljard Euro in R&D investeert, hebben deze technici de vrijheid en de middelen om de technologische grenzen te verleggen. Alleen zo kan ASML haar leidende positie in de wereld behouden.

“Bij ASML heb ik kennisgemaakt met de andere kant van het spectrum. Ontwikkeling gaat hier razendsnel. Ik had vooraf niet gedacht in deze industrie terecht te komen, maar hier liggen duidelijke vragen op mijn vakgebied,” aldus Marijn Wouters, ASML Integration Engineer en voormalig Masterstudent Lucht- en Ruimtevaarttechniek. “Ik heb de tijd en vrijheid om de dingen in kaart te brengen en goed te beargumenteren. ASML heeft een open cultuur en ook naar stagiaires wordt goed geluisterd en meegedacht.

Met een studie Lucht- en Ruimtevaarttechniek denk je niet direct aan de halfgeleiderindustrie, maar ik ben bijzonder blij dat ik deze wereld beter heb leren kennen.”

LEREN! ASML is een ideale omgeving voor professionele ontwikkeling en groei. Heb jij een grenzeloze passie voor technologie en wil je deel uitmaken van een team dat elke dag nieuwe ideeën uitprobeert en constant op zoek is naar betere, nauwkeurigere en snellere werkmethoden? Ga dan naar www. asml.com/students.

Werken bij het NLR Kijk voor vacatures en stages:

www.werkenbijhetnlr.nl

Het NLR is dĂŠ plek voor iedereen met een passie voor techniek.

Wil jij je talenten benutten en je persoonlijk ontplooien?

Als medewerker krijg je bij het NLR alle ruimte!

Nederlands Lucht- en Ruimtevaartcentrum

Come on board

Are you passionate about aviation and do you want to: • • • •

Work on many of the world’s most exciting and largest aerospace projects Be part of a large aerospace company Be inspired in an innovation and technology driven culture Contribute to a growth strategy

Take a look at fokker.com, go to careers, read about what we have to offer you and come on board.

Fokker Technologies, a division of GKN Aerospace, is a leading global aerospace specialist that develops and manufactures highly engineered advanced aircraft systems, components and services for aircraft manufacturers and airlines worldwide.

Colleagues in the Netherlands, Romania, Turkey, Canada, Mexico, USA, China, India and Singapore share your passion for Aerospace.

GKN Aerospace, the parent company of Fokker Technologies, is a global first tier supplier of wing, fuselage and engine structures, nacelle systems, landing gear and wiring systems, transparencies, ice protection systems and aftermarket services, with a global workforce of over 17,000 employees in 15 countries.