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).
Preliminary calculations for a 4 1/2' carcase sequence starter motor, including armature and field specifications.
| Identifier | ExFiles\Box 61b\3\ scan0261 | |
| Date | 17th December 1931 | |
| X6091 To By.{R.W. Bailey - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. c. to By/Rd. Hs{Lord Ernest Hives - Chair}/Wst.1/MA.17.12.31. J.3. SEQUENCE STARTER MOTOR. We have now completed preliminary calculations for this 4 1/2" carcase motor and append them herewith so that it can be ascertained whether the windings are practicable. Our calculations are based on the assumption that at maximum engine turning over torque the speed of the engine will be 80 R.P.M. We are basing the engine torque proportionately to the engine swept volume, and turning torque figures supplied by By/Rd. ARMATURE. 39 slots, 78 conductors i.e. one turn per coil. Diameter 2.700" length 3.500". Slot area .300 sq.ins. Slot depth .300 inches. Slot width .100 inches. Use strip .036" x .130". FIELD. Main 4 1/2 turns of 12 SWG D.S.C. wire. Teazer. 30 turns of 18SWG D.S.C. wire. Carcase thickness same as 20/25. This field circuit is based on an estimated ampere-turn figure of 320 with an assumed increase due to armature reaction of 50%. Current to produce the estimated torque 127 amperes at 9.46 volts. We should be interested to know if these figures are practicable because if not we shall have to recalculate assuming other speed, torque and ampere figures. Hs{Lord Ernest Hives - Chair}/Wst. | ||