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).
Design changes for the Goshawk I dynamo, including armature diameter and slot numbers, following a discussion with Mr. Royce.
| Identifier | ExFiles\Box 39\2\ Scan071 | |
| Date | 1st June 1921 | |
| X.3533. To Da.{Bernard Day - Chassis Design} from EFC. c. Ey. c. De/Thr. c. Ey/WER. EFC5/T1.6.21. X.3533 - GOSHAWK I DYNAMO. During my visit to Mr. Royce, the dynamo for Goshawk I was discussed. The calculations made by Mr. Thacker and myself for this machine were shown to Mr. Royce and he considered that the machine would not do in the form already instructed. He came to the conclusion, as I think we had previously considered, that the armature diameter was too small and that this should be put up to 3.250" in place of 2.800". He considered that the flux per pole at the cutting in point should be 150,000. It will be remembered that we had calculated out armatures with 31 and 27 slots respectively, but owing to these figures not being of the form 4 m + 1, to which form Mr. Royce considers the number of slots in any machine should comply, he decided upon the number 29, intermediate between these two, for the number of slots now required and that we should only make one kind of armature for this machine, this armature to have 29 sections of 10 turns per section of No.19 S.W.G. if possible, otherwise of No.20 S.W.G. He queried as to whether this would be too ambitious. The step of the coil and of the connection at the commutator end would be 7 slots in each case. The number of conductors would be 20 times 29 = 580, and we should make an effort to use No.19 S.W.G. | ||