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).
Performance calculation sheet comparing engine capacity, weight, and axle ratio for a 20 HP model.
| Identifier | ExFiles\Box 107\4\ scan0095 | |
| Date | 16th August 1929 guessed | |
| -2- Taking the figure for litres/ton mile supplied by Hs.{Lord Ernest Hives - Chair}, the 20 HP. is 2820. for 33 cwts total weight. Chassis weight equals 24 cwt: Increased capacity (3.2 bore).. 14% Saving in weight, take as...... 5% (This assumes body etc. does not exceed 7.5 cwt.) Lower axle ratio............... 5% 24% 2820 X 124% = 3500 as compared with 3670 for the SS.{S. Smith} We assume the master period will have gone up on the new crankshaft sufficiently to permit of the present top speed with a lower axle ratio, if the latter is found to be desirable. The question of compression ratio does not of course enter into the above calculation, as the contemplated increase can only be considered as bringing the M.E.P. into line with the SS.{S. Smith} and our competitors. E.{Mr Elliott - Chief Engineer} | ||