THE CURRIE WOT

W orld's smullest turbo-prop aircraft

I'T is always a pleasure to witness an historic occasion and Bill Barber and I were among about t lO0 guests of the Gas Turbine Subsidiary of the Rover Co. Ltd. at Birmingham (Elmdon) Airport to inspect and see flying demonstrations of the first Turbo-prop. powered Ultra Lightthe Currie Wot.

Rover's connection with the development of at Elmdon gave proof that a light turbo-prop. Gas Turbine engines goes back to 1940 and engine can compete successfully with reciprothe early WhittG jet engines; and, following cating engines in the 130 h.p. class' the war, they maintained a team of develop- The Currie Wot was fitted with the smaller ment engineers to study such installations in of the two engines that will be marketed motor cars-culminating in the appearance of initially, designated the T.P./60, giving 70 Jet I at Silverstone in 1950 and the first speed b.h.p. for take ofi (at 47,OOO r.p.-.1 unO OO trials in Belgium in 1952. b.h.p. at max. cruise and the small basic size progress with industrial applications of Gas of the engine (30 inches) made possible a very Turbines also went ahead and for the past two neat installation in the aircraft. A larger years Mr. Viv. Bellamy, of the Hampshire version, the T.P.i90, will be available at a later heroplane Club, has had discussions with the date and this will develop up to 120 b.h.p. Rover Co. Ltd., concerning their suitability for Both engines have a single stage, centrifugal light aircraft propulsion and the demonstration compressor, one reverse flow combustion chamber and a single stage turbine and are similar in weight and external dimersions; the increased performance of the T.P./90 engine being achieved by refinements in the compressor and turbine allowing a greater air mass flow and higher exhaust temperatures.

Power is transmitted in the Currie Wot installation via a manually operated variable pitch propeller; the operating mechanism was designed by the Rover Gas Turbines Ltd. and the blades were manufactured by HordernRichmond Ltd.; their operation has proved to be trouble free though it is expected that a hydraulically operated V.P. prop. will b: specified for the larger engine.

It is expected that Rover's will market complete power plant installations and the standard accessory list covers all items and instruments necessary for an installed weight, both engines, of 235 lb. The price may be about f1,500competitive with British and American engines in the 130 h.p. class when the expected extended overhaul life is achieved but not, perhaps, yet within the reach of the 'amateur constructor.

The advantages of such an engine installation are mainly centred on vibration free and quiet operation and I can think of many current light aircraft which would benefit by such an installation, but low maintenance requirements, accessibility of units and long life are also attractive 'by products' of the gas turbine, with extra safety ensured by ability to run on kerosene or diesel fuel.

A very stimulating flying demonstration was given by Viv. Bellamy and ws, in the Popular Flying Assocation, would like to echo the remarks made by Mr. M. C. Wilks, the Managing Director of Rover Gas Turbines Ltd., in a speech before his demonstration " . . . You will soon see a flight demorstration in the Currie Wot aircraft and I would like to pay a tribute to Mr. Bellamy who has put so much enthusiasm and effort into the flying work in connection with this developmentwithout these efforts of course we should not be here today."

New Bngineering Charges

The recently announced revised overall charges for Engineering Services to P.F'.A. members are as follows:-

" We have over 60 active flying groups and negotiations ate in hand with another 12 groups. The petrol rebate applications for these groups, now coming in, show a considerable increase on the flying hours recorded for the period ending in June 1960, and we hope to start this summer a unified flying training scheme for groups in the London area whereby training groups take on temporary pupils from non-training groups thus increasing the overall aircraft utilisation in the future."

Paying For Airports

The following letter, under the signature of Mr. J. V. Hose, of Warlingham, SurreY, appeared tn " The Times " recentlY:

60 Active Flying Groups

Mr. David Armstrong, chairman of the P.F.A., in his annual report to the Royal Aero Club, stated:-

"Amateur construction of ultra light aircraft has developed during the year with abofi 24 fixed wing aircraft nearing completion, and great interest has been shown in rotating wing ultra light aircraft, about 12 of which are under construction. We have approved the plans of nine types of aircraft and, in addition, are guiding the design of a number of new aircraft.

" The responsibility delegated to us by the M.O.A. and A.R.B. has necessitated a volun' tary engineering staff of over 20 and this work is oew controlled from technical offices situated at Luton and CoventrY.

" You kindly printed a letter from me strongly criticizing the Ministry of Aviation's attitude towards the private aircraft at London (Heathrow) Airport. I mentioned particularly the tctal ban on single-engined aircraft'

" I am delighted to be able to state that as a result of representations which I made to the Minister of Aviation, his Ministry have confirmed to me that modern, properly equipped, single-engined aircraft will no longer be banned. This is a major concession, although a long way from the total freedom which the private flyer desires and has a right to expect at the airPort.

" Praise must be forthcoming where praise is due, and the new Minister must be congratulated for doing something really colstructive for the private flYer at last."

Personal Accident Insurance

Willis Faber and Dumas Ltd. announce that they are now in a position to ofier cover to our member groups. The insurance is for members of the group, and is on a seat basis.

The premium for the pilot's seat is I o/", i.e. flO premium per f1,000 cover, and insures all pilot members of the group. Premium for the passenger members of the group is I2l-"/" per passenger seat per aircraft, i.e. f.6 per f,1,000 cover.

Salvaging An Aeronca

Three R.A.F. officers have introduced a variant on the familiar " do-it-yourself " theme by setting out to restore to flying condition a badly damaged aircraft which had been consigned to scrap.

Flight Lieutenant Giles Baker, son of Air Chief Marshall Sir John Baker, salvaged a single-engined two-seater Aeronca (circa 1936) and set about rebuilding it at the Central Flying School, Little Rissington, Glos. He was joined in this by two friends, Flight Lieutenant Alan Jones and Pilot Officer Thomas Salter, both technical officers.

First they beat out new panels for the engine cowling. Then began the major job of reconstructing the shattered wing. Now the aircraft's rehabilitation is almost complete. With a new propeller on order, they hope to have the aircraft flying by the spring.

" But," says Flight Lieutenant Baker, " it has been no easy job. This aircraft has a 36-ft. wing span and as we had no drawings we had to work things out as we went along, But, with the aid of modern materials, we now have a better aircraft than the original."

Cost ? f 135 for the wreck, and another hundred or so for refurbishing-'( much cheaper than buying a new aircraft."

Obituary

We regret to record the death of Mr. Douglas Jack Last, of Corpusty Mill, Corpusty, Norfolk, a member of the North Norfolk flying group at Felthorpe. Mr. Last, who was 45, was killed while visiting the Waveney flying group at Seething, near Bungay. A freak wind threw one of the aircraft 6ft. into the air and it struck and killed Mr. Last as it hit the ground. We extend our condolences to Mr. Last's widow and two sons.

Purt 2 : The Fubric Couerirug

n NE of the most important materials in lLl g.o"ral use on light aircraft, is the fabric covering. When doped, this material has an extraordinary strength factor for its very light weight anrd[ although quite satisfactorily forms a wing control or fuselage sarrface, the shape of these co nponents nevertheless rely eutirely on the structure of the aircraft.

Further, the fabric covering does in fact contribute towards the strength of the completed component and so the method of application and repair are importart and of course, the condition of the fabric during its life. For all this, the internal structure, which will be dealt with in a later issue' must still be capable of taking the loads applied in various conditions of flight, according to the conditions of the Permit or Certif,cate of Airworthiness. One of the general conditions of a Permit is that the aircraft is non aerobatic and this is for a very good reason.

Three Types of Fabric

There are three types of fabric in general use, which will be described in turn' The first is an Irish unbleached linen and is known in the aircraft world as DTD 540 and is obtainable off rolls 38" and 54" width' This fabric has extraordinary strength and when doped properly will stand up to most weather conditions very well and has quite a long useful life. Indeed, this fabric has stood up to quite high speeds and engine power, as we well know from pre-war fighter aircraft' There are two disadvantages in this fabric from the ultra-light and amateur constructor's point of view and they are weight and expense' Although this material forms a very light covering for its strength, nevertheless, for ultra-light aircraft and their capabilities, DTD 540 fabric may be regarded as unnecessarily heavy and strong. The cost of DTD 540 fabric is as much as 6/11 per yard or the 38" rotrl and 916 pe:r Yard on the 54" roll.

The fabric we are really concerned with and the type in g:noral use on light aircraft,

by A. Deuerell,

is DTD 575, a cotton fabric possessing a str:ngth well within the requirements of ultralight aftcraft ancl indeed, is even to be found on some aircraft types of the 2,000lb' category and engine powers in the 150 b'h'p' realm' Possessing the advantages of being lighter and cheaper than DTD 540, this material is obviously ideal for our needs' DTD 575 possesses one great drawback and that is when doped, any damage caused by a stone, etc'' can spread; in other words, a small tear or hole can very soon develop into a long rip' Great care, therefore' must be taken during sewing operations and any damage, no matter how small, must be attended to immediately'

On the other hand, DTD 540 fabric, unless in poor condition, has a very strong resistance to damage spreading; try and tear sorne by hand and you will see what I mean' This is' of course, no excuse for neglecting damage' DTD 575 cotton fabric is on rolls 53" wide only and costs 615 Pet Yard'

The third tYPe of rnaterial used is Madapolam DTD 343a, supplied in 53" rolls and works out to 517 a yard' This extremely light fabric has no useful strength whatever and is never to be used as in the normal sense of fabric coverings. It has a valuable uso' however, and that is to cover the external of all p1y surfaces. Madapolam is applied direct to the ply with the aid of dope and so forms ,rn absclute weather proof exterior and after rubbing down, provides a good base for a srnocth and glossy linal finish. It is this typically British technique that usually provides a better flnish and better timber protection on British built wooden airqaft as compared to foreign built machines. Perhaps the best known example was the fabulous " Mosquito," with its remarkable finish and capability to stand up to climatic conditions abroad, in spite of being all wood. The simple answer was, doped madapolam. Great care is necessary when applying this material in order to prevent bubbles as then the whole surface is spoilt. While the dope is wet apply the madapolarn and thoroughly rub down each area as applied, with a pad of the same material to exclude all traces of air between the material and the ply. If this in done correctly and with patience, a fine smooth weather proof surface can be achieved.

Do not store fabric in damp conditions or in a place where the cloth will undergo extremes of temperature.

Now we come to covering, say, a wing with the fabric of our choice, DTD 575. Because of the span size and the width of ro11 being only 53", obviously a number of lengths will have to be seamed together according to the size of the wing. These seams must be chord' wise, i.e. in the direction of flight and the type of seam used is known as the " balloon " seam and must be of a laid down width of f" with a double row of back stitching, each row f" from the edge.

A Strong Joint

It is advisable to do this seaming by machine and so lengths off the roll are cut according to the wing and then removed and stitched up on a sewing machine. Unless stated otherwise on the drawing, the warp and the weft of the material travel chordwise and spanwise and so a little care is needed when preparing fabric for a tapered or swept back

Popular Flying, Januaryl February, 196l wing; the ribs can give a clue in these cases. The edges requiring seaming are folded back *", one downwards and the other upwards, and from this one can simply tuck the former into the latter. Ensure that each it tucked in the full distance in order to take full advantage of the two rows of stitching at the distance mentioned above. A very strong joint is then achieved. The thread used on aircraft is a linen thread released to ARB requirements and the two sizes used are, single 18s or double 40s.

On the slower speeds that are usual on ultra-light aircraft, it is quite in order to dope the fabric on the leading edge ply (assuming the leading edge is a "D" section box as on " Turbuleflt," " Condor," etc.) for a distance of not less than four inches from the rear edge of the ply, then pass the fabric back over the ribs, round the trailing edge, back towards the leading edge on the other surface and finally doped for at least four inches on the leading edge ply. The remainder of the bare ply on the leading edge, is covered with doped on madapolam and the joint of the madapolam and fabric is then sealed with fabric tape doped on. The whole wing then receives one coat of dope well scrubbed in, this is to ensure that the dope penetrates. We are now ready for stringing the fabric to the ribs but before we do, there is one little important point. It is a bad thing for the dope to stick the fabric to the ribs, etc., and there are two ways of preventing this. One is the use of dope resisting white paint. The idea

Aircraft Maintenance and Construction (continued)

is to paint or spray all surfaces liable to contact dope where we do not wish. Rib booms are one example. The other method is to use cellotape which, of course, resists all dopes and paints for that matter. It is quite easy to put strips of this tape along rib booms, etc., and this material has a great point in its favour and that is that it cannot absorb moisture which would be detrimental to the fabric resting on it and it also acts as an excellent anti-chafe at possible points of friction such as the point of contact between fabric and ribs, and trailing edge. Now that the fabric has one coat of dope, we are now ready for the stringing operation. The idea of this is to attach the fabric to the ribs and so not only keep the wing shape under all conditions but to prevent the fabric covering from flapping under certain conditions of flight.

To be Continued

BOOK REYIEW Memoirs of an Airline Pilot

o'Fate is the Hunter " by Ernest K. Ganl (Hodder and Stoughton, Ztl-)

" Fatg is the Hunter " is the splendidly written life story of an airline pilot. There are no dull moments in a fascinating series of aerial adventures beginning at the time when the author leaves " the semi-starvation of itinerant flying " for one of the Amprican airlines until, two million flying hour$ later, on a moonlight night high over the Pacific between Honolulu and the mainland, he decides to, " set down the old flight bag for the last time."

The author vividly describes the trials and tribulations of his apprenticeship days as a co-pilot fly,rng DC-2's between Newark and Cleveland during which phase he has an opportunity of appreciating the flying qualities of his captain. This during a nightmare trip in storm conditions for which apparently the route is notorious. " Our altitude o'f more than two miles above the eqrth is /ess than half tha:t ol the mo,st pro'minent thunderheads. The' pholanx forms a solid precipice which tumbles straight down lrom the edge of our wing'tip, grey-black and green in the last light. Gre'at blossomin:g l,^e/,e of dirty white churn again:st each other all the way to its gloomy foun:dations. In:side the darker oreqs there aye frequent explosions o'f light, marked simul' taneously by savqge crashes in our e'Q:rphones." Thus the scene is set for Capt. Ross to pull so,me' superb flying out of the' bag.

During the war Gann flew with Air Transport Command and one of his assignments was flying Lockheed Lodestars to Rio via the west coast of S. America and thence eastwards over the Andesin aircraft not equipped with oxygen. Apart from that and also the navigation of hundreds of miles of uncharted territory he also had to contend with unfriendly mechanics tampering with the engrnes.

In other chapters the author describes an unusually thrilling take-off which nearly ended in the writing-off of the Taj Mahal, the drama of wartime supply missions over the Greenland ice-cap, the challenge of flying over The Hump, plus various near-disasters for good measure. In fact as the title implies, the author is concerned about fate as it decides the life or death of a pilot and a long obituary list at the beginning of the volume-" their fortune was not as good as mine," says Gann -more than makes the point. Another theme, constantly hammered home throughout the volume, - is Gann's scathing criticism o'f the seniority system-" the accursed numbers to which we were all slaves. yet how they could devise and fix our destinies ! "

Throughout the book the reader has a consciousness of the real joy of flying and is alongside Gant in his awareness of a nearness to the infinite. There is indeed poetry in this volume which will be avidly read by all those who find serenity in the upper layers'

G.

For th,e informati,o'n, of reoders, and particularly neut members Flying" prhl,ish,es bel,oru the requlations relating l;o the of P.F.A., " Popular Permit-to-Fly.