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).
Design of an electrical starting device for the 'Eagle' engine.
| Identifier | ExFiles\Box 37\3\ scan 044 | |
| Date | 8th September 1917 guessed | |
| Controller, Technical Dept., Air Board Office. -3- R1/W21817. experimental parts to be made therefrom in the course of the next seven to ten days. Re Electrical Starting Device.- Commander Bristow assured us that it was possible to obtain a small electro motor weighing 19 lbs and a battery that would give 50 starts of our "Eagle" engine and that this motor would be best fitted with the reduction gear equal to 50 to 1 and would give the necessary torque of 48 lbs. inches at 1500 revs. which with the 50 to 1 reduction gear suggested would turn the engine 30 revs. per minute which is found to be the most economical speed to obtain the maximum number of starts from the battery. We shall, in the course of the next fortnight, endeavour to design suitable gearing for the application of one of the motors suggested to our "Eagle" engine. It is suggested by us that a lighter or more efficient motor can be made if the speed (on the 12 Volt battery) were increased from 1500 to about 2700 and using a gear of 90 to 1 this motor would still turn the engine at 30 revs. per minute and would only require a torque of 5/9 of 48-- 27 lb" at the motor spindle The increased gear reduction does not produce any difficulties with the arrangement we have schemed and of which we hope to send you a drawing in the course of a few days. Our Mr. Royce has been unavoidably called away but will continue these notes in the course of a few days. Yours faithfully, Engineer-in-Chief. | ||