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).
Design considerations for a 12-cylinder chassis, focusing on engine weight and performance.
| Identifier | ExFiles\Box 4\1\ 01-page007 | |
| Date | 6th October 1932 | |
| X4694. To Sg{Arthur F. Sidgreaves - MD} ) from E.{Mr Elliott - Chief Engineer} (Wer) E.1/HP.6.10.32. c.c. Hs.{Lord Ernest Hives - Chair} Sy. Cx.{Major Len W. Cox - Advertising Manager} EM. HM.{Capt. W. Hallam - Head Repairs} re 12 Cylinder Chassis. Performance can be bought very cheaply today, and hence we must not sacrifice this feature to unreal considerations. While, therefore, agreeing in the main with Hs.{Lord Ernest Hives - Chair}W/KT30.9.32 that the engine should not be restricted to 3" bore we would suggest that there are two other features of equal importance, e.g. weight and windage, both of which must be substantially reduced if we are going to make a vehicle which will still not be out-of-date in 6 years time. A big engine is of little use if allied to a cumbersome heavy chassis as in the big Daimler. Weight as we know affects the acceleration, and windage the high speed performance. There should be no disproportion between these two, or we get a result which is unbalanced, and each is as important as the B.M.E.P. developed by the engine. We seek to show that improvements to these features can be, or are being, provided for, or if not must be provided. Dealing with the weight of the engine first, the 12 cylinder design is 3 inches shorter overall than the Phantom II. and leaving out consideration of the flywheel we should not expect this engine to be any heavier than the P.II. even if it had the same cast iron cylinder block and head construction. Now the J.III engine is 85 lbs lighter than the 20/25 in spite of its generally larger size, and this is due to the integral aluminium cylinder block construction alone. We are justified, therefore, in expecting to save | ||