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).
Need to repeat a type test for a Moderate Supercharged F. Engine due to bearing failure caused by detonation, and the proposed solution of reducing the compression ratio.
| Identifier | WestWitteringFiles\T\2January1929-June1929\ Scan091 | |
| Date | 29th January 1929 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to BJ. SG.{Arthur F. Sidgreaves - MD} c. to WoR.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. to RG.{Mr Rowledge} BY.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}2/LG29.1.29. ORIGINAL X3859 / X2965 X3996 / X3196 MODERATE S/C. F.{Mr Friese} ENGINE. The type test on the M.{Mr Moon / Mr Moore} S/C. engine which was recently run is having to be repeated owing to the condition of the bearings. During the type test it was noted that when the engine was running at 525 HP. in the gate position, 2250 r.p.m., the engine was detonating. Towards the end of the test there were signs of detonation at the 9/10ths. position. The condition of the bearings when the engine was stripped down was poor. It was considered that these may have been aggravated by detonation. As the M.{Mr Moon / Mr Moore} S/C. engine is expected to give good power at low altitude, it was thought that it would be a safe policy to reduce the compression ratio. We had ready some pistons giving 5.3 comp. ratio. These pistons were prepared for a high boost engine which the Ministry wished us to try. A set of pistons giving 5.5 ratio were instructed by RG.{Mr Rowledge} These have been made and we attach herewith comparative power curves with 6/1, 5.5 /1 and 5.3 /1 ratio. The intention is that with the lower compression ratio we shall still give the same power at the gate position. The height at which the ground power will be restored will be lower. It will be noted that with the 5.5 ratio we can still give the performance we have promised to Contractors, although the power is less at the lower speeds, the gate contd :- | ||