DIESEL AEROPLANES

Nelson Evening Mail, Volume LXIII, 29 July 1929, Page 7

DIESEL AEROPLANES

FIRST MACHINE TESTED DETROIT-WASHINGTON FUG 11T America's first Diesel or oil-fuelled airplane, which has jus). Ilown from Detroit. to Langley Field, Washington, for its first, public inspection by leading aeronautical experts, may lm the first of a new breed of aeronautical power, plants that may drive the gasoline-car-burettor sort of engino o-ut of the sky. For several years the Packard engineers. under the direction of Captain L. M. Woolson, have been developing tlio now engine that lias just been allowed to perform in public. Tho ordinary person would not give it a second glance, so conventional docs if seem in outward appearances. But, to the engineer who lias seen Diesel engines capture tlio "'propulsion of sea-going ships from steam turbines, who has watched the application of oil engines to power plants and sizeable construction machinery, who has even sa-u the coming of Dieselpowered automobile trucks, the Packard engine, consuming the sort of oil that is burned in furnaces and driving a standard typo aeroplane for six hours across country, comes as a portent. Little wonder, then, that pilots, research scientists, and aeroplane manufacturers visiting the Langley .Memorial Aeronautical Laboratory crowded around tho Packard engine when its locked covers were unfastened. Nino cylinders, air cooled, arranged radially, compose the Packard aeroplane engine. The familiar spark plugs and tho carburettor so unnecessary on a gasoline engine are lacking. One valve in each cylinder head acts as an air inlet and burned fuol exhaust, The fuel oil, instead of gasolino—is sprayed into tho cylinder instead of being mixed with air and vapourised into a carburettor. The heat of compression of the squeezed air in the contracting cylinder ignites the oil sprayed into it. Tims electrical ignition is dispensed with. The engine is of the four-stroke type, and operates at from 1700 to 2000 revolutions per minute, with cylinder pressures as high as 12001 b per squaro inch. For a given mileage, the fuel cost, is onlv about a sixth that of a gasolinefuelled engine. ,Tho present design weighs about three pounds per horsepower, a remarkablo record, despite the fact that standard gasoline airplane engines .weigh less than two pounds per horse-power. Engineers hjivo estimated that for long flights tho saving in fuel weight due to the use of oil instead of 'gasoline will make tlio Diosel engine more economical, despite its heavier weight. Starting a Diesel engine presents more difficulties than for a gasoline engine, Sinco the firing of the fuel mixture in the cylinder is accomplished by tho heat of compression of tho air, a much swifter kick must be given in starting. Whilo the exact method of starting the Packard engine is not yet revealed, those who saw tho Langley Field demonstration are of the opinion that- tlio necessary impulse lT given by the firing of a powder cartridge. Once the engine is warnteef by running it can be stopped and started in the more conventional manner. In tho laboratory of tho National Advisory Committee for Aeronautics at Langley Field a Diesel type airship engine of six cylinders is now operating under test conditions. An ordinary airship carburettor type gasolino engine was converted to burn oil as a result of the investigations on one-cylinder oil engines that have been 'in progress' for several years. The development will speed the application of oil engines to airships, and possibly to automobiles. British engineers are developing oil Diesel-type engines for the large airships now building. The Benrdmore engineers in England have also given attention to tho possibilities of oil-pow-ered airplane engines- In Germany and Fiance similar work is in progress, although details are lacking, because of the secrecy that surrounds all investigations. /