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).
Continued discussion on motor calculations and performance, specifically addressing abnormal results due to a high reduction ratio.
| Identifier | ExFiles\Box 64\1\ scan0127 | |
| Date | 30th May 1923 | |
| EFC2/T30.5.23. -2- Contd. particularly the high reduction ratio, have resulted in the various calculations made for this motor, leading to results rather out of the ordinary and have caused us a good deal of thinking as to the true inter-relation of the various quantities. It has appeared to us all along that this size of motor, working with the reduction ratio given, must necessarily come out rather abnormal. Our final conclusions are that it does not necess- arily result in a motor with a large number of armature conductors, but rather one with a moderate number only, a large flux and an abnormally large proportion of field resistance to armature resistance. This seems more especially so, supposing that the original assumptions and particularly those set forth in your RL/M16.5.23 are adhered to, though as a matter of fact everything seems to indicate that in the unusual circumstances the efficiency might be assumed considerably higher than 50%, and therefore the current considerably less than 200 amperes. This therefore we have done in the calculations. That is, unless we assume a torque figure greater than 1400 lb-inches, which we have taken, but which itself was based on your values of the efficiency, volts, amperes and engine speed. A torque of 1400 lb-inches, however, seems a reasonable figure for the worst condition, as compared with 900 usually assumed for the ordinarily cold condition. We have, therefore, made calculations to suit an efficiency of | ||