Aircraft Engineering THE MONTHLY ORGAN OF THE AERONAUTICAL ENGINEERING PROFESSION VOL XXV No 295 SEPTEMBER 1953 S.B.A.C. DISPLAY • FARNBOROUGH • SEPTEMBER 7—13 • STAND NO. 64 order often to one, are the most remarkable examples of engineering development in this field. T may be remembered that at this time last year, on the occasion Again the rapidly expanding range of operating conditions, of the last S.B.A.C. Display, we published an article by M R A. F. particularly the increase in aircraft ceiling, has brought problems I NEWELL, which brought together the history of aircraft design of fuel supply and control which have only been solved at the cost and development since the war. This seemed appropriate because of further complexity, as can be seen for example in the Dowty the efforts of these years could then be seen to be culminating in the Spill Burner fuel system described in our May issue; once again the outstanding aircraft to be seen at the display. Such a survey also extension of a system, itself simple in principle, to cover all operating serves, we believe, a useful function in enabling one to stand back conditions, has involved considerable mechanical complexity. and see the lines of development which must be obscure to many in the industry at the time because they are too near to certain aspects Two Comparisons of current work. Those coming into the industry for the first time may also find it useful to have some means of discovering the stages PROFESSOR BAXTER'S article, in accord with the spirit of the that led up to current developments. S.B.A.C. Display, deals exclusively with British engines. The recent Paris Salon gave an opportunity to see, among others, two American It is for these reasons that we asked PROFESSOR BAXTER, who, we engines of special interest. One is of course the Pratt and Whittney need hardly add, is Head of the Department of Aircraft Propulsion T-34 turbo-prop. This departs in several respects from British at the College of Aeronautics, to contribute to our Farnborough issue practice. The power is given as 5,600 e.h.p. for a basic engine weight this year an article which would perform a like function for aero of 2,550 lb., or a specific weight of 0·455 lb./h.p. The power is engines. The result appears on the following pages. absorbed by one propeller with steel blades of special design, the It does not detract from the achievements of the aircraft designers diameter being fifteen feet. This engine is therefore of greater power to say that the realization of their work is dependent upon the than we have adopted in this country, except in coupled turbo-prop availability of suitable power plant, and it is a truism that the deve units. This may be in part due to the fact that current plans for the lopment of the aircraft gas turbine during and since the war is the use of the T-34 are for developments of existing piston engined chief reason for the rapid advances in aircraft performance that have aircraft, the Super Constellation and Globemaster, while our turbo characterized the period. It is in the field of propulsion, too, that prop aircraft have been designed from the beginning around the Britain can claim to have led in the post-war world. There is no sign engines. It is presumably easier to fit a single turbo-prop into a of her relinquishing that lead. structure originally intended for a radial piston engine than to accommodate a coupled unit. Complexity The American contribution to the compound engine is of course To turn to the engines themselves, it is interesting to see how the the Wright Turbo Compound, but as suggested by PROFESSOR general trend to greater complication in aircraft (and also, be it said, BAXTER, this engine is hardly comparable with the Napier Nomad, in other branches of engineering) has also been manifest in the rapid which is a more recent, and much more radical approach to the development of the gas turbine for aircraft use. The early types, with problem of reducing fuel consumption. However it may be interesting their centrifugal compressors, single-stage turbines and the bare to recall that the specified fuel consumption of the American engine essentials in the way of auxiliaries, were hailed as the forerunners of is 0·63 to 0·67 lb./b.h.p.-hr., which is nearly double that quoted greatly simplified aero-engines and this was thought to be one of for the Nomad, although the weight (3,484 lb.) and frontal area their greatest advantages. Yet as the demand for greater output, (about 171/2 sq. ft.) are both less. The power is about the same in lower specific fuel consumption and smaller frontal area increased, each case. the jet engine, though retaining its fundamental simplicity of prin ciple, became mechanically more complex, and hopes that here was The Newcomer a cheaper power plant had to be abandoned. Considerations of performance led to the almost universal use of the axial-flow com As if to demonstrate the fact of continuing advance in British pressor, with its many stages, and large numbers of costly blades. aircraft gas turbine design there has been the recent announcement The very complexity of the axial compressor has entailed intensive of the de Havilland Gyron turbo-jet; too recent in fact for it to detailed research to derive the greatest benefit from its potentialities. be mentioned in the article, not that any information has yet been Perhaps the rapidity with which the troubles found in the early released about this engine, except that it is an axial-flow type of high axials, mainly due to vibration, and matching of compressor and output intended for supersonic aircraft. turbine characteristics, have been overcome, together with the It is unfortunate, from the point of view of a publication like response of the gear designers to the problem of coupling a gas AIRCRAFT ENGINEERING, that development and research work on turbine delivering 4,000 h.p. to a propeller at a reduction of the gas turbines has to be so closely shrouded by security measures.
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Sep 1, 1953