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).
Bench test results for the R.R. Goshawk starter motor.
| Identifier | ExFiles\Box 35\4\ scan 119 | |
| Date | 14th July 1922 | |
| X4384 To R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} from EFC. c. to CJ. & PN{Mr Northey}‡ c. to By.{R.W. Bailey - Chief Engineer} & EP.{G. Eric Platford - Chief Quality Engineer} c. to Rg.{Mr Rowledge} & Da.{Bernard Day - Chassis Design} EFC1/T14.7.22. X.4384 - R.R. GOSHAWK STARTER MOTOR. The results of bench tests carried out on the first R.R. Goshawk starter motors were very satisfactory as regards running and general performance. We made very careful tests with a view to fixing up the best average angular location of the brush system, and we found this to correspond ultimately to 3° advance of the brushes as compared with the no current neutral position. In this position we obtained the highest speed-torque curve without materially affecting the ampere-torque curve. The ampere-torque curve obtained experimentally, which showed a current of 140 amperes to be required for a torque of 66 lb-inches, agreed almost exactly with our calculated figures. (N.B. we have proved independently by actual experiment that the ampere-torque curve was very little altered by taking it at different speeds, i.e. different voltages). The speed-torque curve on the other hand did not come up to our expectations. Our calculated value showed a speed of 810 r.p.m., whereas the average speed observed was about 730 r.p.m. against this torque at 66 lb-inches. From the results actually obtained on the Goshawk chassis, however, it would appear that the motor is quite suitable for this purpose, as no complaint has been received of the motor not turning the engine fast enough for a satisfactory start. Contd. | ||