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).
Calculations for new crankshafts comparing the effect of different journal and pin dimensions on engine speed.
| Identifier | ExFiles\Box 85\5\ scan0101 | |
| Date | 17th July 1935 guessed | |
| Calculations for new crankshafts based on - (1) Effect of 2.5 dia. journals on existing crank raises speed 150 r.p.m. (2) Narrow 1" pin crank speed 5320 r.p.m. (3) Relative stiffness of 2.5 journals on (2) as opposed to 2¼" journals and 2.7" dia. journals 51/39 Changes in journals only of (2) gives 150 x 39/51 = 110 rpm. ∴ 210 is due to pin stiffness and decrease in inertia. ∴ 1" pin crank with 2.5 dia. journals would have speed of 5360. 1" wide pins give 210 r.p.m. over standard. 1⅛" " " " 175 " " " 1¼" " " " 110 " " " | ||