Prospects for Use of “Safety Fuels” in Spark-Ignition Aircraft Engines

RECENT developments in fuel-refining processes have developed new safety fuels, and have revived general interest in the subject, Mr. Mock reports. “Safety” or fireproof aircraft fuels, he explains, must be less volatile than gasoline and should have a flash point of about 105 F, a distillation range between 375 and 475 F, and about 87 octane rating. In his paper he summarizes the program probably necessary before such fuels can be employed successfully in every-day service operations. Three methods of fuel feed are discussed: injection into the cylinder, into the intake pipes, and into the supercharger. Injection into the cylinder, he reports, has been tested on a full-scale engine on the dynamometer with some success, but it was not flown. Injection into the supercharger, he feels, is attractive because of its simplicity. Five detail problems are listed: injection equipment; changes in engine and cylinder; fuel-air metering and power control; starting; and installation. Of these, Mr. Mock remarks that the injection equipment and fuel-air metering and power control are well developed; changes in engine and cylinder have been started; and starting remains to be solved. He concludes that safety fuel can be used but not without considerable research taking three or four years, which will eventuate in certain changes in engine design.