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 page discussing motor performance, torque-ampere characteristics, and armature design.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan135 | |
| Date | 22th June 1927 guessed | |
| Contd. -3- torque-ampere characteristic then suffers, not only directly but also as a result of armature reaction, we do not realise any actual improvement in speed against a given large torque. Our motor performances are always compared on a supply characteristic of one volt drop from 12 volts per 50 amperes which is approximately the same as, though often a little less favourable than, the characteristic of motor supply realised on a chassis. On this characteristic of supply and with a motor in a given temperature condition it is apparent that for any given torque at which a motor has to work there is some number of field turns in a given winding space which will result in the highest motor speed against that torque. This may not be the same number for a low torque as for a high, but we are of the opinion that the number should be arranged to be the best for some selected high torque corresponding to nearly the maximum stalling torque of the engine. We do not get so good a static torque ampere curve with this 45 slot armature as with the 41 slot parallel armature of the No.1 scheme. We do not know how that of the 41 slot taper armature of the No.2A scheme on J motor on 14-EX compares because we have not had an opportunity of making this test on that motor. The engine speed performance of this motor on that chassis is good in this weather, when the engine torque is not much more than 500 lb-inches, but might not be very good with a very cold engine. | ||