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 implications of weight and engine size for the Wraith replacement model.
| Identifier | ExFiles\Box 148\2\ scan0083 | |
| Date | 25th November 1938 | |
| -2- Rm{William Robotham - Chief Engineer}5/R.25.11.38. Weight increase, which of course is largely proportionate to body dimensions, is cumulative. The body gets heavier, the frame has to be made heavier to take care of the long wheelbase, the road springs heavier to carry the body, the tyre size increased, and, finally, as more fuel is of necessity used to propel the heavier vehicle, the tankage has to be increased. To deal with this increased weight a lower bottom gear has to be provided. Bottom gear torque is responsible for the maximum stresses on the gearbox, propeller shaft and rear axle. Briefly, what we are trying to say is that we may be able to stretch the rationalised pieces to cover engine displacement from 4¼-litres to 5¼-litres, providing the maximum car weight does not exceed 43 cwts., but we cannot stretch these pieces to cover this range of engine size, and also car weights from 34 to 52 cwts. It is almost certain that we should get up to 52 cwts with a P.III size of body and the chassis modifications necessitated thereby. If it is decided that it is a paying proposition to design, test and produce a large number of parts outside the rationalised programme specifically to cater for 10% of the P.III customers who would not be satisfied with an 8-cylinder engine in the Wraith Replacement chassis, then we can go ahead with the necessary design work. Personally, we should not have thought that the potential turnover created thereby would have justified such a procedure. If we start this new car, we should like to suggest that we get some information from the Wraith Replacement - which will be available in three months' time - before we go too far with the project. WRAITH REPLACEMENT Rm.{William Robotham - Chief Engineer} | ||