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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.

THE need for improvement of fuel consumption in modern aircraft is stressed. The basic economy of oil engines for airline service is briefly summarized, together with the effect of lower fuel consumption on the range and payload of airplanes. The theoretical efficiencies of the Otto and Diesel cycles are compared with the efficiency actually obtained on present aircraft engines. The data are presented in condensed graphic form for easy comparison. A prediction is made of the fuel economy that may be expected from the gasoline aircraft-engine in the near future, together with a summary of the means required to obtain it. The prospective place of the compression-ignition engine in commercial and military service is briefly outlined. An analysis of the weight possibilities of compression-ignition engines as compared to present gasoline engines is made.

THERE has, for many years, been a demand for an automotive engine more economical in operation than the gasoline engine. As the Diesel engine had early established a good reputation for economy, the development work on a more economical automotive engine quite naturally centered around this type of engine. Additional advantages can, however, be gained by combining fuel injection with spark ignition, and an engine of this type has been developed by K. J. E. Hesselman of Stockholm, Sweden. This engine is generally called the Hesselman engine. In the spark-ignition fuel-injection engine the charge is formed at a certain time before the spark occurs, and this makes it possible to mix fuel and air thoroughly whereby high output is secured. Engines operating on fuel oil with a compression ratio of 7.5 : 1 have given a brake mean effective pressure of over 125 lb. per. sq. in.

THE purpose of this paper is, first, to set down the methods which have been considered in the effort to develop a gasoline-type engine which will operate satisfactorily on non-volatile fuels, such as furnace or heating oil: Second, to describe briefly commercial examples of the use of these various methods: Third, to analyze the possibilities of these several processes with regard to power and efficiency, comparing them-as well as the results to be expected from the use of motor gasoline-with those of an engine operating on aviation gasoline as a basic standard. Mr. Dutcher concludes that there are cases where horsepower hours per dollar's worth of fuel can be just as-or more-important than horsepower per pound of engine.

DR. SCHNAUFFER presents in this paper the results of research on and measurements of combustion processes in internal-combustion engines by means of a slow-motion camera and a micro-chronometer. This method for flame-propagation indication depends on the physical property of flame to ionize air gaps and hence make them conductors of electric current. The recording equipment used is very simple, he says, and can be simplified still further if only visual inspection of the combustion processes is desired. He gives also a brief review of the history of combustion-process research, and a bibliography. Using this method, all the conditions affecting the speed of flame-propagation in a high-speed spark-ignition engine were examined, and Dr. Schnauffer emphasizes that the results were accurate. Neon lamps can be substituted for an oscillograph, if desired, and are less expensive; further, this makes possible the registration of an unlimited number of test points.

To improve the cold startability of methanol, methanol-butane mixed fuel was experimented. Engine performance and exhaust emissions are obtained with methanol-butane mixed fuel. These characteristics are compared with those of methanol and gasoline. The mixing ratios of methanol and butane are 50:50 (M50), 80:20 (M80), and 90:10 (M90) based on the calorific value. As a result, M90 produces more power than gasoline and more or less than methanol depending on the engine speed and the excess air ratio. Brake horse power of M90 is higher than that of gasoline by 5 - 10 %, and brake specific fuel consumption is smaller than that of gasoline by 17 % to the maximum based on the calorific value. NOx emission concentrations for M90 are lower than those for gasoline and higher than those for methanol because of the effect of butane, CO emission concentrations are somewhat lower than those for methanol and gasoline.