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).
Analysis of engine performance, specific consumption, and rate of climb for different compression ratios, with a comparison to a Napier 10.A engine.
| Identifier | ExFiles\Box 36\2\ scan 223 | |
| Date | 8th June 1929 guessed | |
| contd :- -2- for these particular engines at different speeds - see appended print - and have estimated the power output at the two altitudes. We then obtained a figure for the specific consumption in flight. On the 6/1 ratio this works out at an average of .504 pts/BHP/hr. and on the 7/1 ratio .475 pts/BHP/hr. which results are in close agreement with test bed figures. We have a figure for the Napier 10.A. of 24.1 galls. hr. at 2350 r.p.m. at 14,500 ft. Two points on the power curve are given viz : 553 at 2350 r.p.m. and 583 at 2585 r.p.m. From these figures the consumption in flight would work out at .57 pts/BHP/hr. but we doubt that the best amount of a.c. was employed in this case. The consumptions of these normal F.{Mr Friese} engines there- fore appear quite good in flight which should render them very suitable for long range work. Figures for the time and rate of climb are appended and shew the advantage of the higher compression ratio where the rate of climb at 15,000 ft. is increased from 250 ft/min. to 350 ft/min. or 35%. The average increase in H.P. given by the high compression engines is 10%. Actually the power curve of this particular 6/1 engine is about 2% below the average but such variation does not seem unreasonable. The rate of climb of the Napier 10.A. is consider- ably in advance of our 7/1 engine and if we refer to the power curves we see that the 10.A. curve is precisely the same as the contd :- | ||