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).
Aero engine performance, detonation test failures, and proposed solutions involving piston compression ratios.
| Identifier | ExFiles\Box 36\2\ scan 234 | |
| Date | 20th February 1929 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} C To SG.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} C To RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} C To BY.{R.W. Bailey - Chief Engineer} AERO ENGINES:- Major Ross and Capt. Forsyth visited the Works this afternoon and various matters were discussed with Wor.{Arthur Wormald - General Works Manager}, BY.{R.W. Bailey - Chief Engineer}, and Hs.{Lord Ernest Hives - Chair} - RG{Mr Rowledge} being away ill. The chief point of discussion was rating of the F.{Mr Friese} S/C. engines. The position is that we have both full S/C. engines and Moderate S/C. engines fitted to aircraft which have 6/1 compression ratio pistons. Recent tests carried out at the works shew that these engines will not pass the recent test which has been added to the Type Test conditions, namely, Detonation at the take off speeds of the propeller. Therefore, although those engines are out and giving a remarkably good performance - (Hawker 'Hornet' with a full S/C.F. engine is giving over 200 m.p.h. at 20.000 ft. which is at least 20 m.p.h. faster than a similar machine fitted with a Mercury engine) they would not be accepted as satisfactory engines because they would not pass the detonation test. In order to overcome this point, we have fitted 5.5 comp. ratio pistons to both the M.S/C. engines and F.S/C. engines. The result of this is that instead of maintaining our power on the F.S/C. engine at 11,500 ft we reduce it to 10,500 ft. and on the M.S/C. engines instead of maintaining our power at 4,000 ft. it is reduced to 2500 ft. When we lower the compression cont'd :- | ||