FASTER PLANES

Evening Star, Issue 25813, 8 June 1946, Page 12

FASTER PLANES

SMALLER AERODROMES l :, EXPERT'S FORECAST A forecast that, with the development of gas turbines and jet propulsion, aircraft will not only become faster, but will require smaller aerodromes and be less noisy, is made in an article by Air Commodore L. G. S. Payne, air correspondent of the London ,' Daily Telegraph.' His conclusions are of considerable interest here.. '■''.'.*•

If evidence that Britain is producing the world's finest gas turbines were needed, the recently released, details of the Rolls-Royce 'Nene should suffice, says the article. _ This is,, the most powerful aero-engine now in production in any country, although it is only one of a whole series of turbine motors being developed by various British firms.

At 600 m.p.h. the Nene will develop, the equivalent of 15,000 h.p.' Yet it weighs only 1,6001 b, has a maximum diameter of 4)ft I.sin, and an overall length, without the jet pipe, of sft 3.9 in. .. .. ' The Series 1. Nene is considerably more powerful that the Series V. Rolls-Royce Derwent used in the re-cord-breaking Gloster Meteor; and there is no doubt that gas turbines of still greater power will shortly be developed. Enormous thrust and power from engines of very small size and weight will not merely create new problems for commercial aircraft designers. It means that many previously conceived ideas about future air transport-must be discarded; .For example, planes with greatlyimproved take-off power will not need vast' airports;"with runways extending for .two or three miles, such as those now* under construction at' Idlewild, Long Island, and at Heathrow, near Hounslow. Thousands of airfields in all parts of the;world which are now considered too small for ■' modern " giant airliners may be ; good enough for the transport planes of to-morrow. An immense saving of valuable' land in built-up areas and of great sums which would otherwise have been expended on new airfield construction, may be possible. The development of British commercial aviation is still obstructed by political prejudice and by people in authority who seem unable or _unwill-r ing to perceive the shape .of things to come. Vague expressions of opinion are still heard about a belief in flyingboats. Millions of pounds are.to be wasted on British mammoth commercial land-planes and flying-boats which will be out ox date before they can fly. " Speed,.it is frequently said, is the only thing_ the aircraft has to sell. It is certainly the principal advantage of air as compared with land and sea travel. ' Yet Lord Winster, Minister of Civil Aviation,., said recently tfyat if higher speeds were v ali :we could achieve by, the; use of gas turbines he would not lay much stress on their introduction.' ■

"It might be useful," he added, l \ to have very ;.fast services, but to .my mind, it is far more important that we should have cheap ones, and it is here that the gas turbine engines can help us." '"'• This seems to be a somewhat limited conception of the revolution in the rapidity of air travel which gas turbines will bring about. They' will make air journeys faster, safer; more reliable and regular j and less tedious; but whether "they will ultimately make them cheaper is problematical. Speed is usually expensive. • Although we have not yet produced the new types of' 4 commercial planes to catch' up, with our own developments in the engine fiekh three distinct stages in ,the design > of :: turbine-driven airliners can already beforeseen. As we pass through each. of these stages we shall find ourselves entering by a natural. process of development, the stage 'immediately following. First, it will be necessary.to design commercial planes which ,v ; when powered by gas turbines driving air: screws, will be able to cruise at from 300 to 450 m.p.h. Airliners with piston engines, capt able of cruising at 400 m.p.h., such as the American. Rainbow, made, by $4 Republic Aviation Corporation, have already been ordered by United States Airlines, . and '" are in , Deliveries will begin early next year. The use of gas turbines instead of piston engines to drive airscrews would, however, give us motors, of greatly-increased power and much less weight. 1 „ It would also confer other, important advantages, such as simplicity of construction, less risk of mechanical breakdown, easy maintenance, and decreased danger of fire owing to the use of safer, and incidentally cheaper fuels. Secondly, we must' develop commercial planes able to :; fly at ; far. greater heights in, a more rarefied ; atmosphere where there is less air resistance, and speeds of from 500 to 650 m.p.h. can consequently be attained. ' At such speeds the jet is more efficient than the airscrew.. Therefore; these high-speed, high-altitude, planes will be driven by pure jet propulsion; and it will be possible, when this stage is reached, to dispense with propellers. When we no longer use propellers or reciprocating: piston engines, noise and vibration will be much reduced.. Pressurised cabins, ■ to 4 enable the passengers and crew to withstand, the effects of flying at 40,000 feet or more will constitute an important problem at. this stage. "..'•■' Thirdly, aircraft of entirely new, design will be required 'to penetrate the strange barrier of air resistance, which is encountered as we approach the speed of sound; That speed is attained at 760 m.p.h. at ground level, but. as it varies with the temperatures, it falls to 660 m.p.h. at 30,000 feet. At sonic speeds the air, instead of flowing normally over the wing surfaces of the high-speed aircraft, tends to build up into a solid, wall of resistance in front of it. This not only imposes severe structural strains on the aircraft, but also produces disruptive effects, such as loss of ?lift, stability, and control To overcome this difficulty planes of novel shape and different wing sections will be needed. It may be.that the future air liner'will be somewhat similar in. design to the German Me. 163,' a small plane popularly known as "the flying firework," which was propelled by a liquid rocket unit not very, different in principle from that used in the V2 weapon. The Me.163 was a monoplane with very back-swept wings and a vertical fin and rudder, but no tailplane. After taking off it.jettisoned its wheels and landed on a skid. Its shape was reminiscent of the paper darts made by school children.

The best shape for penetrating, the wall of. resistance, encountered at sonic speeds_ will be determined by experiments with models in wind tunnels,

in which very high speeds of 1,500 m.p.h. or more can how be stimulated. - Mr Strachey, the Onder-Secrtitary for Air, has told;us that, judging*;from the way' science is moving, it will be possible in the not very distant future to break through this, barrier of ajr resistance Phenomenal speeds will then be practicable. For such-speeds new tvpes of aircraft will certainly be needed; but jet-propulsion units capable of driving planes at 1,000 m.p.h. or more appear, even rnpw, to present' no insuperable difficulties. - Meanwhile: we should overhaul oui plans and be wary of heavy expenditure that may subsequently prove to have been unnecessary. Many well? qualified experts, believe.that, in so.'fat as commercial air ; transport is coticerned, we 6h6uld now concentrate ajl our resources-on new types of mediumsized, •': high-speed planes powered .with gas turbines, 'and ruthlessly scrap al! other long-term projects. ; -■• ; -«, .This, they think, might obviate an expensive and unproductive -era of giant land and sea planes and theiir concomitants, ', vast airfields or flvihgboat bases, each costing several" million pounds. ,'." .':• ■■'■ "-■■ '" -'v