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 applying a Goshawk II motor to a Goshawk I engine.
| Identifier | ExFiles\Box 35\4\ scan 047 | |
| Date | 23th August 1921 | |
| X.4384 - GOSHAWK II MOTOR APPLIED TO GOSHAWK I ENGINE. Torque required to turn Goshawk I engine = 500 lb-inches. Speed reduction ratio = 14.4 Take 90% gearing efficiency then effective torque ratio = .90 x 14.4 = 12.96 Motor torque when rolling engine is therefore 38.6 lb-inches. Equivalent static torque = 42.5 If the flux were the same as for Goshawk II at the reduced current required to roll the engine, that current would be C = (Tb x 10^8) / (1.41 Z P Φ) = (42.5 x 2 x 10^8) / (1.41 x 116 x 4 x 161000) = 81 amperes. But flux would be less, not in proportion of 137 to actual current (say about 95 amps) but in some intermediate proportion, say to 116 amperes. We therefore estimate reduced flux to be 116/137 of 161000 = 136,500 Contd. | ||