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 starting a B60 engine at 0°F.
| Identifier | ExFiles\Box 165\7\ img027 | |
| Date | 28th May 1910 guessed | |
| B60 Engine at 0°F Assume an Engine resisting Torque of 100 lb ft. Then, using a gear ratio of 12:1 and allowing for an efficiency of 80% the requirements at the starter will be 100 / (12 x .8) = 100 / 9.6 = 10.4 lb.ft. M45G motor at 10.4 lb ft and a terminal voltage of 8 will run at 700 RPM., giving an engine speed of approx 58 RPM. Current draw at the above torque = 320 amperes. Watts required = 8 x 320 = 2,560 HP Input = 2560 / 746 = 3.4 HP Output = (58 x 100 x 2π) / 33000 = (58 x 44) / (7 x 330) = (58 x 4) / (7 x 30) = 232 / 210 = 1.11 overall eff = 1.11 / 3.4 = 32.5% [Left Margin Notes] 41/26 128.5 / 3 = 41.6 41.6 = 1.3PS eff of motor 10.4 x 41.6 x 700 / (7 x 33000) | ||