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).
Test results for a Phantom II starter motor fitted with an experimental 29-slot armature.
| Identifier | ExFiles\Box 62\1\ scan0189 | |
| Date | 24th October 1933 | |
| E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to By/RD. 86091 Hs{Lord Ernest Hives - Chair}/Wst.3/MA.24.10.33. P.II STARTER MOTOR WITH 29 SLOT ARMATURE. We have tested out a P.II motor fitted with a 29 slot armature having larger gauge conductors. Our tests shewed an increase in max. BHP. with this armature as compared with standard, of .35 which is an increase of 40%. The stalling torque, as anticipated, was lower however being 150 lbs-ins. as compared with approx. 170 on the standard motor. The maximum efficiency was .575 as compared with .49 on the standard machine. We consider that we have gone a little too far in the reduction of the armature conductors as we do not want to reduce the stalling torque to the extent we have with this experimental armature. The 33 slot armature we have asked for should be approximately OK. as regards maximum BHP., Efficiency and reasonable stalling torque. An interesting point about this 29 slot armature was that on the teazer winding the armature torque was reduced considerably such as to be hardly appreciable. This is due to the fact that although the reduction in armature resistance has little effect on the teazer circuit the reduction in armature conductors considerably reduces the torque from a given current. fm Hs{Lord Ernest Hives - Chair}/Wst. | ||