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).
Engine characteristics, fuel consumption, and performance with a fixed pitch airscrew.
| Identifier | ExFiles\Box 134\1\ scan0048 | |
| Date | 26th November 1937 guessed | |
| -3- engine characteristics, rather than altitude. At 15,000 ft., the optimum back pressures for maximum speed vary from 2½ to 4½ lbs/sq.in. at speeds from 250 to 400 MPH., corresponding to exit areas of .019 to .014 sq.ins. per engine B.H.P. Under cruising conditions, where maximum fuel economy is required for a given aircraft speed, a high back pressure will give the best results, but insufficient engine data is at present available to predict them with any degree of accuracy. It can, however, be stated quite definitely, that the gain in fuel consumption or cruising performance, will be greater than the gain in top speed performance. A series of cruising consumption tests should be undertaken at Hucknall when a flowmeter is available for the 'Battle'. Gain in Speed due to increase in Engine Power with fixed pitch airscrew. Since the tests have been carried out with a fixed pitch airscrew, the increase in speed obtained is accompanied by an increase in engine R.P.M. and boost pressure, the effect of which on the machine speed can be assessed from a knowledge of engine power characteristics at full throttle, assuming that BHP. ∝ V³. Curve HK.{Col. T. Harker - Sales} 702 shows the order of the power increase with R.P.M., estimated from the results of full throttle power curves on fully supercharged engines, and the corresponding effect on machine speed over a range of speeds from 200 - 400 MPH. --------- Dor{Mr Dorey}/T. P. de Paravicini. | ||