Lot 996
THE INVENTION, DEVELOPMENT AND PROMOTION OF THE FIRST TURBOJET ENGINE
FRANK WHITTLE (1907-1996) English Air Commodore, inventor and engineer credited with the invention of the first operating turbojet engine which culminated in the first British jet-engined aircraft, the Gloster E.28/39, flying on 15th May 1941. A most historically important set of documents documenting Whittle's earth-shaking invention. The first document, prepared by Whittle but unsigned, although with a few corrections in his hand, is titled: 'Report on First Tests of an Experimental Gas Turbine by Squadron-Leader F. Whittle, R.A.F.', this being the first confidential report delivered to the Air Ministry by Whittle's Power Jets Ltd. ‘in fulfilment of Item No.1 of Research Contract', 36pp. sm. folio, with three fold-out appendices at the conclusion, [n.p.], Mar. 31, 1938. This carbon typescript report describes in great detail the initial tests of a constant pressure gas turbine intended for aircraft propulsion by jet reaction and the experiments carried out under Whittle's supervision between April and August 1937, this being the earliest practical test of what would become today's modern turbojet engine. Whittle's introduction reads, in small part: '...At the time when the development of the propulsion unit was under consideration, there was no intention of making a complete engine at once, partly because definite ideas as to its final form were rather nebulous, but mainly because a sufficient knowledge of the performance of the different components for design purposes was lacking. It was therefore intended to adopt a step by step process, commencing with tests on a high speed single stage centrifugal compressor. It was decided that this should be of the size to be used in the engine…because it was believed that to make tests on a smaller scale would lead to misleading results'. The document continues with elaborate and detailed reports on Design and Construction including the strength of the materials when exposed to high temperature, the rotor assembly, the ‘very unorthodox feature' of the turbine nozzle, etc., the results of Preliminary Combustion Tests (‘These tests at least proved that the required combustion rates could be obtained, though for various reasons, they did not provide sufficient information for the avoidance of combustion trouble in the engine itself……Ignition of the atomising sprays by high tension spark proved to be easy at moderate air speeds, but as the electrodes were damaged early in the tests, ignition was mainly achieved by the insertion of burning oily waste through a flap…The quality of combustion was judged by the appearance of the flame, the presence or otherwise of visible smoke or fuel vapour, and the smell and the effect on the eyes of the exhaust'), Tests with Atomising Sprays, Plain Sprays (‘The flame was very intense, and for the speed, the combustion was the best that had been achieved up to that time. It appeared, however, that the system was very sensitive to jet alignment, and this was largely true of all similar systems tried'), Testing Arrangements (‘For test purposes, the unit was mounted on a four wheeled trailer. This trailer also carried the starter motor, instrument board and controls, making the set self-contained with the exception of the fuel and water supply….For starting, it was considered to be necessary to spin the rotor up to about 3000 r.p.m. after which it was expected to be capable of accelerating under its own power…The instruments and their connections were considerably modified in the course of the tests...The tachometer was mounted on the top of the gear case in such a position that it could be seen through a hole in the instrument board'), further providing a description of the test runs of the unit, subdivided into four categories, in part, ‘For the test runs, the starting procedure was as follows:- The rotor was motored over at about 1000 r.p.m. and the pilot jet ignited by the hand magneto. The speed was then raised to 2000 r.p.m., at which speed the main jet was opened and the unit accelerated under its own power…..No trouble was ever experienced in starting other than occasional trouble with the initial ignition through cracked electrodes, and in fact the very first attempt to start was successful……Five runs were made with this system, the maximum speed reached being 8,500 r.p.m. beyond which the unit would not accelerate on further opening of the control…uncontrolled acceleration occurred in one case, otherwise it was found possible to hold the unit at a steady speed with the control', also giving a discussion of the results and Whittle's conclusions. A document of exceptional content and major significance in Whittle's development of the jet engine, the historical importance of which cannot be overstated, the jet engine being one of the most important of the twentieth century, affecting the life of almost very human being. Loosely bound in the original plain paper wrappers, all of the pages with two files holes to the left margin. Some very light, minor overall age wear and some light staining and a few minor tears to the edges of the paper covers, else fine condition. SOLD WITH: a typed D.S., 6pp. sm. folio, folio, [Lutterworth, Rugby], Apr. 22, 1940, titled: 'General Memorandum on the Design and Production of Gyrone Engines' and providing a brief outline of the design requirements of this jet engine variation, a progenitor of the DeHavilland Gyron which would power supersonic aircraft within a decade. Whittle discusses: 'Performance...Minimum weight...Simplicity in starting and control...Mechanical reliability...Ease of maintenance...Suitability for quantity production and Cheapness of manufacture', etc., in part: ‘The purpose of the engine is to give aircraft the maximum possible performance for their particular duty, i.e. for an interceptor fighter, high rate of climb, high maximum speed, etc, and for a bomber, high speed and load carrying capacity with long range…The overall efficiency of the engine is extremely sensitive to the efficiencies of the components...The overall efficiency depends on the thermal efficiency and the propulsive efficiency...a higher positive-negative work ratio will lead to greater thermal efficiency, but also a higher jet speed, and hence a reduction in propulsive efficiency. In any case a balance has to be struck between the requirement for a high compression ratio and for a high positive-negative work ratio, and higher mass throughput, in order that the stress and temperature imposed on the turbine will be within the capacity of the material employed to withstand them...the efficiencies of the compressor and turbine are so important that they must not be penalised except in the most minor way by other requirements….For example, it may be said that methods for producing the turbine blades should be adapted to the design requirements, rather than that the design should conform to available standard methods of production…The all-up weight of the engine is very important...and...certain extra manufacturing processes are often worth while in order to obtain weight reduction. What may be a ‘commercial job' for normal purposes is not necessarily a commercial job for flight purposes if weight reduction has been subordinated to ease of manufacture to an extent which penalises the aircraft performance…The Gyrone engine is at present primarily intended for interceptor fighters, and hence the starting arrangements must be such that the time to get off the ground must be an absolute minimum. This requires that starting arrangements should be speedy, and also that the design of the engine should be such that it is capable of being run up to full speed without danger of damage due to thermal expansions...Control must be simple and reliable, and the engine must be quick in response..the Gyrone engine is mechanically so simple that there are very few parts to go wrong, and provided that all materials used are sound and not unduly overloaded, there should be little fear of mechanical breakdown…It must be possible for all parts...to be readily accessible…the simplicity of the engine is such that maintenance should call for little more than the cleaning of filters…the engine must be made as easy as possible to remove from the aeroplane, and should be easy to strip and re-assemble…For aero engine purposes cheapness of manufacture necessarily gives precedence to many over-riding requirements, and in the case of the Gyrone engine the manufacture is basically so much more simple that it is of even less importance...'. SOLD WITH: typed D.S., 4pp. sm. folio, [Lutterworth, Rugby], May 17, 1940, titled: 'Memorandum on the Design of Gyrone Engines', outlining the general nature of the design and development problems of the Gyrone jet engine. In part: ‘The Gyrone engine is mechanically simple, but the design engineers require to have an extremely wide range of engineering knowledge and experience because the design covers an unusually large field of problems…Both turbine and compressor theory overlaps so far into the field of aerodynamic knowledge that a sound grounding in aerodynamics is necessary to the Gyrone designer...the utmost in the way of efficiency must be obtained, both from the air compressor and the turbine...the commercial turbine world has been slow to make use of up-to-date aerodynamic theory, and when they do use it it is often to abuse it. Because of the relative ignorance of commercial designers a vicious circle has been operating in the history of the gas turbine…the designer must…be familiar with the engine/aircraft combination, and must have in mind many factors of operation which are peculiar to the aeroplane, e,g. centrifugal forces and gyroscopic effects in turns, atmospheric conditions at different heights and in different parts of the world etc. It is here that the turbine designer finds himself on unfamiliar ground…when he is faced with the problem of a turbine for aircraft purposes he finds himself in a completely strange world where his engine can be subjected to ‘tight' turns of an order which may black out the pilot and cause appreciable gyroscopic effects etc. He would also find that the range of operating conditions is quite outside his experience, as for example the necessity to start up and get off the ground in less than two minutes..He will not realise the importance of it being possible for the pilot to produce a sudden extra burst of power when he finds himself undershooting the aerodrome, or when finding an enemy aircraft sitting on his tail…It is of course obvious that these [design] stages overlap very considerably, and the fact that it is an aero engine has to be borne constantly in mind from the earliest moment...manufacturing requirements must be kept constantly in mind throughout the design, though, as with all aero engines, manufacturing requirements must give way to the need for operational efficiency to a degree quite foreign to normal commercial work'. Some trivial edge tears and wear. SOLD WITH: an historically important T.L.S., 2pp. 4to., Ladywood Works, Lutterworth, Rugby, May 18, 1940 to Air Vice Marshal ARTHUR W. TEDDER. Whittle writes to Tedder following a talk they had together on 10th May, and forwards the two memoranda described above. He continues: ‘...That talk did me a lot of good, and had a very beneficial effect on my peace of mind. I did not mean to say by that that I like the arrangements which the Air Ministry have made any better than I did, but I hope that we shall be able to overcome the main potential sources of trouble by making special arrangements to deal with them', adding that relationships with the Rover Company are as good as he could hope them to be (‘the engineers concerned will have to do the best they can to keep the atmosphere sweet'), expressing his desire to meet Tedder again so that he can explain some difficulties to be guarded against, remarking ‘An example of the sort of thing which causes me a lot of worry is the very serious delay which has occurred with the experimental apparatus for a pressure combustion test set. In this matter we came to the conclusion that such a set was urgently necessary early in February…and in the meantime we got on with the W.X. idea. We came to the conclusion early in March that the W.X. scheme was the best all-round one for the purpose…we sent the W.X. layout drawing to the [British engineering and heavy industrial company] B[ritish] T[homson-] H[ouston] on the 18th April, since when nothing has been settled. I took the law into my own hands two days ago and gave the B.T.H. instructions to proceed on the W.X. scheme, saying at the same time that it was probable that so much experimental work on combustion was contemplated that if they had a suitable motor driven compressor scheme it would be required as well'. In concluding Whittle conveys another concern to Tedder, ‘One quite different matter which I think needs urgent consideration now is how this development is going to be affected if the enemy makes strong air attacks on this Country. It seems to me that if Sheffield were intensively bombed we should be indefinitely held up, as the production of the special steel forgings is the main bottle neck of the job. I do not think it is wild to suggest that the removal of the whole of this development work to the other side of the Atlantic should be contemplated'.
The invention of the turbo-jet engine, and the determined effort to design and develop it to replace piston engines in the air, was one of the most important technical achievements of the 20th century. That one man accomplished this, working with a small but dedicated team of engineers and craftsman in the middle of a war, and in the face of many doubters, was a truly monumental achievement. But the British Government, despite giving Whittle and Power Jets a contract, still remained unconvinced. Had the RAF been equipped with jet-powered fighters during the Battle of Britain and the rest of the war, victory could have been hasted by years. And his invention took its toll of Whittle as well, the stress bringing on his nervous breakdown in 1940. In 2002, Whittle was ranked number 42 in the BBC poll of the 100 Greatest Britons. Provenance: Acquired by our consignor from John Wilson (Autographs) Ltd. in 1980. In his catalog description Wilson notes that of the five copies which were prepared ‘two, perhaps three, are believed to have been destroyed'. These documents have not been offered for sale in the U.S. until now.
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