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 electrical calculations and specifications for the Goshawk II starter motor.
| Identifier | ExFiles\Box 35\4\ scan 023 | |
| Date | 2nd June 1921 | |
| To Da.{Bernard Day - Chassis Design} from EFC. c. By c. Da{Bernard Day - Chassis Design}/Thr. c. By/WER. X.4384 EFC1/T2.6.21. X.4384 - GOSHAWK II STARTER MOTOR. During my visit to Mr. Royce we made together some preliminary calculations for Goshawk II starter motor. We are expecting to receive from Mr. Elliott sketches showing the exact dimensions settled upon, but in the meanwhile the following are the electrical particulars noted down at the time. Carcase dia. and length 4.750" by 4.500" Armature dia. and active length 2.750" by 2.500". Polar face 64 mm. by 37 mm. This, with a flux density of 8,000 lines per sq. cm. gives 189,000 lines. Mr. Royce ultimately decided upon a flux of 170,000 lines, giving a density of 7,180. There are to be 29 slots and 29 sections of two turns per section, giving 116 conductors in all. The slot dimensions were fixed upon as .160 by .450", the conductors to be round wire No.14 S.W.G. of two turns per section. Polar embrace 74%. For the end connections 1 1/4" was allowed at the back end and 1 1/4" at the commutator end, including the commutator spokes. Commutator dia. 2.00", useful length .625". Mr. Royce desires us to make an estimate of what the weight of this motor would be, also to make complete electrical calculations of the machine, and he suggested that I should go down again when we have these complete for all the machines so that he can finally approve of all the data | ||