Document Type: Technical Research Report Authority: Government Military (authoritative reference) Document Number: Air Service Information Circular (Aviation) Vol. V, No. 465 (dated May 1, 1924), based on McCook Field Report Serial No. 2290 (dated February 15, 1924).

Scope: Material Section report prepared by A.C. Zimmerman, Engineering Division, Air Service, McCook Field, Dayton, Ohio.

Contents: "PURPOSE To determine approximately the content of aromatics, naphthene, and paraffin hydrocarbons of United States gasoline from various sources.

CONCLUSIONS 1. The difference in aromatic content of gasolines from California, Oklahoma, and Pennsylvania crudes is not considered great enough to cause any marked improved functioning in high compression engines. 2. The California gasolines examined contain much greater percentage of naphthenes and consequently lower percentage of paraffins than either the Pennsylvania or Oklahoma products, which probably enhances the anti-detonating qualities.

GENERAL The volatility of the gasoline, regardless of its source or chemical content has been and is being used as a criterion to determine its fitness for use in aviation motors. The results of tests made at the Bureau of Standards in the altitude laboratory, using a 180 horsepower Hispano engine, Type A, compression ratio 5.3 to 1 indicate that at this compression at altitudes of over 5,500 feet the distillation curve of the gasoline apparently has very little influence on the power that can be obtained when the carbureting conditions are suited to the fuel and it is not impracticable to attain these conditions. These tests, however, were performed with pistons giving a compression ratio of 5.3 to 1 and at reduced pressure of altitude conditions, so that the effect of detonation on the power was not evidenced."