FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1940
1940 - 0760.PDF
MARCH 14, 1940 installations. Primarily there is the armament which we shall later give special consideration. Then wireless; night-flying gear; oxygen breathing apparatus; cockpit heating; armour plating; a reflector gun sight; pyro- technics ; possibly flotation gear; and perhaps a special tank for 100 octane fuel or, in the case of a direct-injec- tion engine, a supply of ether and petrol for quick start- ing. Transport practice is apparent in the instrument layout of some new American fighters. For example on the Curtiss Wright 21 intercepter there is a "tell-tale" panel. This system incorporates a visual signal which not only Rearming a Messerschmitt Me 109 single-seater fighter, the standard machine of its class in the German Air Force. The majority of Me 109s so far encountered have carried four machine guns, though a number have been armed with one shell-gun and two machine guns. immediately attracts the pilot's attention to improper operating conditions, but indicates specific items at fault. Eight sets of lights in the panel indicate for low fuel and oil pressures, lean mixture, low airscrew r.p.m., high blower ratio, "flaps down," "landing gear up," and " tank selector off." A great deal of weight and complication is accounted for in a fighter by the power plant installation. The engine of a single-seater, with accessories, airscrew and fuel, may represent something like half the all-up weight and complication is still on the increase. Twin-engined single-seaters have been built for several reasons. One advantage of first importance is the pos- sibility, should the power units be mounted on, or in, the wings (or be "buried" in the fuselage, driving outboard airscrews through shafting) of installing comparatively heavy shell-firing guns in the forward part of the fuselage where their weight is more, conveniently disposed than in an outboard installation on a single-engined tractor machine. Moreover, the tendencies toward reduction in span and increase of airscrew diameter raise additional problems in connection with wing-mounted armament. Access to the breeches of centrally-mounted guns is also feasible and there is the possibility, when the engines or airscrews are outboard, of improving the pilot's forward and downward view, though lateral vision is likely to suffer, particularly if conventional radial engines are specified. Another incidental advantage of the twin-engined or '' outboard-airscrew '' design is the comparative ease of in- corporating a retractable nose wheel, though, as demon- strated in the Bell Airacobra, with a single in-line engine "buried" over the e.g., this is not altogether impossible in a single-engined layout. In the case of long-range single or multi-seater fighters the extra safety afforded by two power units is not to be overlooked. Designers may also benefit from the adoption of twin engines for they will not be limited to the power offered by the most powerful unit available. Manoeuvr- ability can often be enhanced by the use of opposite-rotat- ing airscrews. FIGHTERS (CONTINUED) As for the engines themselves they must have some special characteristics if the highest efficiency is to be attained. Low weight per h.p. is perhaps more essential than in other classes of aircraft;' small frontal area is another factor of extreme importance. In a lecture at the 1938 Conference of the Lilienthal Gesellschaft, Dr. Heinkel stated that 1,800 h.p. could be put behind an area of 10 sq. ft. This figure has been considerably improved upon since the lecture. Supercharging is of primary importance, for a fighter must always '' have the edge '' over other types in ceil- ing and climb and speed at height. Two-speed super- charged engines which render a high take-off output com- patible with power at altitude have not yet been so widely adopted for fighters as for other classes of military air- craft, but these will undoubtedly come more into promin- ence , ~; The ding-dong battle between air and liquid cooling continues. The introduction of the Rolls-Royce Kestrel series of liquid-cooled vee-twelve about ten years ago enabled Great Britain to build the world's fastest fighters. America, at that time, was in the throes of a pro-radial reaction despite the fact that the Curtiss D-12 had enabled American manufacturers (and the Fairey Company) to build some outstandingly fast machines. When the Hurri- cane and the Spitfire, mounting the more powerful Merlin, demonstrated such high performances the U.S. Govern- ment sponsored the development of the Allison liquid- cooled engine and the pendulum swung—quite decisively it seemed—towards the " wet-nosed " fighters. But more recently Pratt and Whitney have developed their Double Wasp two-row radial with extension shaft and have obtained an exceptionally low drag. This combination is installed in the Curtiss P-42 and the Vultee Vanguard ; either or both these machines may before long be seen operating in Europe against the Messerschmitts and Heinkels which, of course, are built round liquid-cooled vee-twelve engines. Engine Layouts A promising engine layout for the light f.ghter is the air-cooled inverted-vee exemplified by the Renault in the Caudron Cyclone. The vee-twelve Walter Sagittas in the Fokker D.23 have similar characteristics but are regarded as expedients. Liquid-cooled vee-twelves and two cr multi-bank radials are likely to retain their popularity for some time, particularly for twin-engined machines, but we may expect H- or V-shaped engines of 1,500-2,000 h.p or more for use in single-engined machines, " Ejector " exhaust systems can be made to benefit both liquid and air-cooled engines, while ducted radiators for liquid-cooled units account for a measure of the perform ance obtained with the Hurricane and Spitfire. An inci- dental problem to be overcome in installing engines in fighters is the damping of exhaust flames in order that the pilot may not be dazzled at night. A basic design of fighter may be progressively adapted to take more powerful engines. In three years since the start of the design of a well-known single-seater there was an increase of 40 per cent, in engine power and a 30 per cent, increase in power-plant weight, justifying the original decision to build a machine of sufficient size and strength to accommodate larger units. The increase in airscrew diameter to absorb the power of modern engines is a serious consideration, particularly in the design of high-speed single-engined fighters. Four- bladed or twin co-axial airscrews ("contra props") now under development promise well and should go far toward preventing the adoption of very " stilty " undercarriages- An airscrew pitch range of about 25 deg. is required 'n a fighter with an engine of 1,100 h.p. to give the best take- off and climb and yet to place no undue strain on the engine in prolonged dives. Increased power, higlir degrees of supercharging, and greater diving speeds w
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
