IIIVESTIGATION OF SUPERCHARGING AN AIR-COOLED ENGINE III FLIGHT

This report presents the resuils of tests made hy the ilTational Ad<sory Commih’ee for Aero-nautics in a preliminary inre~tigation oj the efieck o-f supercharging an air-cooled engine under airplane flight conditions. This investigation comprises the ji%t of its kind that has been conducted andjor ui.ich results hare been published. Serrice training airplanes were used in the investigation equipped with production types of Wright J engines. An AT.A. (7.h. Roots type supercharger was drhen from thQ rear of the engine. In addition to measuring those quantities that would enable the determination. of the climb performance, measurements were made of the cylinder-head temperatures and the carburetor pres-sures and temperatures. The supercharging equipment was not remored from the airplane when making ji?ights w“thout supercharging, but a by-pass ralre, which controned the amount oj super-charging by returning to the cttmospiiere the surplus air delirered by the supercharger, was left fuTl open. With the supei-cliarger so geared that ground-lerel pressure could be maintained to 18,.50(7 ~et-t,it was found that the absolute ceiling was increased from 19,400 to 32,600 feet, that the time to climb to 16,000 feet u’as decreased from 5’$2to 16 minutes, and that this amount of supercharging apparently did not injure the engine