NEXT FIVE YEARS

Evening Post, Volume CXXIII, Issue 69, 23 March 1937, Page 12

NEXT FIVE YEARS

FASTER AIRCRAFT

ENGINES AND WINGS

(From "The Post's" Representative.)

LONDON, February 27,

: Military aeroplanes capable of speeds of more than 400 m.p.h. are, engaging the thoughts of British designers. Mr. A. H. R. Fedden, chief engineer of the Bristol Aeroplane Company's engine department, cited between 425 and 450 m.p.h. as the maximum speed likely to be attained . within the next five years by one category of warplane, in the paper on the trend of air-cooled engine development which he read before the Royal Aeronautical Society. He expects medium bombers to cruise at 300 m.p.h. and heavy bombers at 275 m.p.h. Military .seaplanes may reach 220 m.p.h. in cruising flight. His forecasts of speeds of civil aircraft are 220 m.p.h. for landplanes and 200 m.p.h. for seaplanes. He visualises a class of special long-range aeroplane cruising at 220 m.p.h. and with a "calm-air" range of between 3000 and 4000 miles. AEROPLANE WINGS. Mr. Fedden revealed that aircraft designers are awaiting the results of important research work on the shape of aeroplane wings which may have farreaching effects on engine design. Speeds of ■ the order contemplated meant the use of a good deal of pow.er, therefore a .considerable step up in the unit.size of engines was likely. He proposed to cover his suggested: range of military and civil aircraft by development of four sizes of engine—a 750 h.p. engine weighing, 8201b, 1150 h.p. weighing 12501b, 1550 h.p. weighing 15501b, and 2000 n.p. weighing 21001b. He was optimistic about the future of the compression-ignition ; engine burning heavy oil fuel. Recently the introduction of volatile fuel of "100----octane anti-knock rating"—a technical description indicating great resistance of the fuel to detonation or "knocking" and consequent ability, to burn at higher compressions in the cylinders than were formerly possible—has enabled the designer to get much more power from a given size of engine and at the same time to .burn less fuel for every horsepower produced. He expects that this fueL :in properly designed engines, may lead to an increase in horsepower of some 25 per cent, and reduce fuel consumption by 5 to 7 per cent. He declared that these improvements in electric ignition engines made the case for the compressionignition engine, the chief advantage of which is its. low fuel consumption, more difficult to substantiate, though the price of the fuel was still considerably in favour of the C.I (heavy oil) engine. " "Nevertheless,", continued Mr. Fedden, "the advantages of the greatly minimised fuel risk, the cheaper fuel; elimination of radio interference difficulties, and.the higher order of trustworthiness that should ensue from the C.I. engine are important factors which cannot be overlooked." HEAVY OIL POWER PLANT. He inclined to the view that there was "a great deal to be said for com-pression-ignition engines, in long-range night bombers of moderate performance and some civil aircraft." These engines should be not less than 1000 h.p. in cruising output. They do not give such high power for take-off as the comparable petrol engine; Mr. Fedden looks to the use of some kind of mechanical launching, such as catapulting, to overcome that difficulty. The greater structural weight of the heavy-oil engines is a disadvantage for flying times below 9i hours, at which point the payload is approximately 14 0001b or one-fifth of the all-up weight. Thence onwards the.C.l. engine shows up more and more favourably; at the Atlantic range of 2500 miles (against a4O m.p.h: headwind) the P.ayl°a<i « the Cl.-powered. machine is 15001b greater than that of the. 100-octane craft If the payload be assumed equal inTotn machines, then the C.I. engine gives an increased range, of 190 miles. ENGINES HIDDEN IN WINGS. Mr Fedden forecast that the trend of aircraft design would be; in tns direction of submerging engines entirely within the covering of the wings. "In the larger classes of aircraft, he said "where four or more engines will beinstalled, the wing thickness wil be such as to permit of radial engines being housed inside." His ' first-cate-aory" engine-750 h.p.-suitable for inftallation in specialised twin-engined military aircraft, might, he suggested, •be a flat engine entirely buried in the envelope of the. wing, though for cml aircraft and "general purpose" military aircraft he still favoured the radia unit He considered that the radial engine would hold its own during the five years under review in the three larger categories.