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 and potential improvements for the Peregrine starter motor.
| Identifier | ExFiles\Box 62\1\ scan0053 | |
| Date | 15th August 1932 | |
| X6134 To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Wst. c.c. E.{Mr Elliott - Chief Engineer} Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} Ev.{Ivan Evernden - coachwork} Da.{Bernard Day - Chassis Design} Hs{Lord Ernest Hives - Chair}/Wst.2/AM15.8.32. 'PEREGRINE STARTER MOTOR' We thank you for your R2/M10.8.32. We have already put in hand a second motor with lower resistance main field and armature windings which, as anticipated, has resulted in an increase of approx. 50% in the available torque and which also gives the motor a better acceleration between the compression pressure peaks. There is still, however, insufficient margin of power, in cold winter conditions, for the motor to move the engine rapidly enough over the initial compression peak. The Peregrine has a high compression ratio and once the motor gets the engine bounced over the first compression peak, it revolves it at a good speed. We are accordingly trying a higher gear ratio about 13 : 1 instead of the present 11 : 1. This should enable the motor to accelerate more rapidly and bounce the engine over compression more easily. The Bosch motor on the Alpha Romeo is 3.9" dia. whereas ours is only 3.75" dia. so that our copper and iron quantities are rather tight. Again the cubic capacity of the Alpha is 1750 against our 2360 on the Peregrine. It would be easier generally for all conditions of running, therefore, if we could increase the diameter of our motor to 4". This would enable us to get a better proportion of copper to iron with a correspondingly greater efficiency. Hs{Lord Ernest Hives - Chair}/Wst. | ||