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 the Goshawk II dynamo.
| Identifier | ExFiles\Box 51\1\ Scan010 | |
| Date | 1st June 1921 | |
| To Da.{Bernard Day - Chassis Design} from EFC. c. Ry c. Da{Bernard Day - Chassis Design}/Thr. c. Ry/WER. X. 4383 EFC9/T1.6.21. X.4383 - GOSHAWK II DYNAMO. During my visit to Mr. Royce we made together some preliminary calculations for the Goshawk II dynamo. As it was not easy at the time to record all the details of dimensions it was left with Mr. Elliott that he would send sketches of the machine showing these as soon as possible. The particulars noted by me were, however, as follows :- Carcase dia. 5.25" Armature dia. 3.00" Polar face 70 mm. by 47 mm. Flux per pole 200,000, corresponding to a polar face density of about 6080 lines per sq. cm. Reckoning the necessary cutting in speed to be 750 r.p.m. and allowing one volt for field current in armature, this gives the number of conductors as 290. As this number of conductors was so much smaller than Mr. Royce had previously arrived at for the R.R. dynamo made from starter motor parts, for which reason he asked us to inform him, he considered that the 290 conductors was too small and arranged for two armatures each of 29 slots, one with 6 turns per section giving 348 conductors, and one of 8 turns per section giving 464 conductors. The slot dimension in the 6 turns per section case was estimated to be .425" by .140". It was estimated that only about 400 ampere Contd. | ||