From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Study on the effect of different gasoline qualities on aviation engine performance.
Identifier | ExFiles\Box 50\3\ Scan066 | |
Date | 25th November 1919 guessed | |
Effect of Gasoline Quality on Engine Performance X4305 WITH the present design of aviation engines and the means of vaporizing and distributing the fuel now available, commercial low test automobile gasoline does not give satisfactory performance. Detonation obtained with the compression ratios now in use precludes the use of straight, low test fuels unless anti-detonating compounds are mixed with the fuel. For this reason it would appear impractical to use commercial, low test automobile gasoline in present types of aviation engines, except in emergencies. These conclusions are the result of experiments at McCook Field, which are interesting in view of the fuel situation, particularly as bringing out the fact that present-day gasoline is responsible for rather low engine efficiency. As is well known, the fuel ordinarily used in aviation engines normally has a much lower average boiling and end point than fuels commercially available for general automotive purposes. Distillation curves of the domestic aviation gasoline and commercial automobile gasoline are shown in Fig. 1. The domestic aviation gasoline is the fuel used in the army air service as standard for ordinary flying, but is not composed of as low boiling fractions as those which go to make up the army air service fighting gasoline. The results of the comparative tests which were made on a standard, twelve-cylinder Liberty engine are clearly brought out in the accompanying curves plotted in Fig. 2. In making the tests, a 5 hr. run with aviation gasoline was made, after which a similar run using the low test gasoline was attempted. This could not be completed until 6 per cent of anti-knock compound, consisting of Xylidine, was mixed with the fuel. The net results of the run are shown, as far as power is concerned, in the curves. After the torque stand runs were completed, an inspection of the pistons, cylinders and valves were made. The carbon deposit on the pistons was heavier than is usually obtained with domestic aviation gasoline. The most objectionable characteristics of the low test fuel is its pronounced tendency to detonate with compression ratios which do not cause detonation with ordinary aviation fuels. A notable increase in carbon deposit and in crankcase dilution was also found with the low test fuel. [Graph 1] Y-Axis: DEGREES CENTIGRADE X-Axis: PERCENT DISTILLED Labels: FIRST DROP, DRY POINT, COMMERCIAL LOW TEST GASOLINE, U.S. SPEC. 3511-B, GASOLINE USED DURING FIRST FIVE HOURS ON TORQUE STAND [Graph 2] Y-Axis: CORRECTED BRAKE HORSEPOWER X-Axis: REVOLUTIONS PER MINUTE OF ENGINE Labels: DOMESTIC AVIATION GASOLINE, BAROMETER 29.92 IN.HG. AVERAGE AIR TEMP. 92°F. {Mr Friese} , COMMERCIAL, LOW TEST AUTOMOBILE GASOLINE, NORMAL SPEED, BAROMETER 29.92 IN.HG. AVERAGE AIR TEMP. 80°F. {Mr Friese} , COMMERCIAL LOW TEST AUTOMOBILE GASOLINE, DOMESTIC AVIATION GASOLINE Fig. 1 (Left)—Distillation curves of commercial automobile gasoline and two grades of gasoline used in aircraft engines. Fig. 2 (Right)—Power and fuel consumption curves, showing performance of Liberty twelve-cylinder aircraft engine using commercial automobile gasoline and domestic aviation gasoline. Results corrected to standard temperature and barometric pressure | ||