DIESEL AEROPLANES

Taranaki Daily News, 24 July 1929, Page 3

DIESEL AEROPLANES

FIRST MACHINE TESTED.

DETROIT-WASHINGTON FLIGHT.

America’s first Diesel or oil-fuelled airplane, which has just flown from Detroit to Langley Field, Washington, for its first public inspection by leading aeronautical experts, may be the first of a new breed of aeronautical power plants that may drive the gasoline-car-burettor sort of engine out of the sky. For several years the Packard engineers, under the direction of Captain L. M. Woolsoil, have been developing the new engine that has just been allowed to perform in public. The ordinary person would not give it a second glance, so conventional does it seem in outward appearances. But to the engineer who has seen Diesel engines capture the 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 seen the coming of Dieselpowered automobile trucks, the Packard engine, consuming the sort of oil that is burned in furnaces and driving a standard type 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 the Packard engine when its locked covers were unfastened.

Nine cylinders, air cooled, arranged radially, compose the Packard aeroplane engine. The familiar spark plugs and the carburettor so necessary on a •gasoline engine are lacking. One valve

in each cylinder head acts as an air inlet and burned fuel exhaust. The fueloil, instead of gasoline —is sprayed into the cylinder instead of being mixed with air and vapourised into a carbuettor. The heat of compression of the squeezed air in the contracting cylinder ignites the oil sprayed into it. Thus 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 square inch. For a given mileage, the fuel cost is only about a sixth that of a gasolinefuelled engine. The present design weighs about three pounds per horsepower, a remarkable record, despite the fact that standard gasoline airplane engines weigh less than two pounds per horse-power. Engineers have estimated that for long flights the saving in fuel weight due to the use of oil instead of gasoline will make the Diesel engine more economical, despite its heavier weight.

Starting a Diesel engine presents more difficulties than for a gasoline engine. Since the firing of the fuel mixture in the cylinder is accomplished by the heat of compression of the air, a much swifter kick must be given in starting. While the exact method of starting the Packard engine is not yet revealed, those who saw the Laugley Field demonstration, are of the opinion that the necessary impulse is given by the firing of a powder cartridge. Once the engine is warmed by running it can be stopped and started in the more conventional manner.

In the laboratory of the National Advisory Committee for Aeronautics ,at Laugley Field a Diesel type airship engine of six cylinders is now operating under test conditions. An ordinary airship carji’iettor type gasoline engine was converted to burn oil as a result of the investigations on one-ey-liuder 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 Beardmore engineers m England have also given attention to the. possibilities of oil-powered airplane engines. In Germany and France similar work is in progress, although details are lacking, because of the secrecy that surrounds all investigations.