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).
Requesting design information for redesigning a starter motor for the EAC chassis.
| Identifier | WestWitteringFiles\P\2October1926-December1926\ Scan052 | |
| Date | 9th November 1926 | |
| To ~~FFC~~ FROM AJS C. to ~~BY~~ HS{Lord Ernest Hives - Chair} ORIGINAL SEQUENCE STARTER. In redesigning this starter for EAC. chassis we shall endeavour to eliminate the epicyclic reduction gear, by using a smaller starter pinion. If we use a 1¼" pinion with the existing flywheel gear of 16¼" it gives a ratio of 13 to 1., or is equivalent to the motor running at approximately 800 RPM. with the engine turning at 60 RPM. In reference to the foregoing would you please let us have a torque speed characteristic for the present Phantom starter motor: also would you kindly let us know how long it will take for the motor to dangerously overheat if stalled. It appears to us that the starter motor will be required to give normally 70 in/ lbs. at 800 RPM., or .85 BHP. at 800 RPM. Assuming .66 efficiency this becomes .130 electrical HP., which is equal to 80 amps. with 12 volts. We should like to know how many armature segments this will require, and whether you get the efficiency mentioned above, and also what windings you recommend. We should be glad of this information as early as you can possibly let us have it. AJS. | ||