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).
Comparison of armature designs, recommending a 24-slot Phantom armature for experimental construction.
| Identifier | ExFiles\Box 68\4\ scan0143 | |
| Date | 4th March 1929 guessed | |
| contd :- -2- (1) Though the total iron armature section is somewhat less than in the 32 slot case, the copper resistance is less to a much greater extent, thus providing a better allround performance. (2) There is no reason to suppose that in passing from 28 slots to the smaller number 24 we shall increase noisiness appreciably, and as regards commutation we shall still have 48 segments which is a considerably larger number than the old 29 segments with which commutation was not too good. We recommend in the first instance, a 24 slot Phantom armature be constructed experimentally. This will have 48 coils of 4 turns each (or 24 sections of 8 turns) 47 of which are wave connected and one lap connected as in the present standard 28 slot armature. The slot pitch of the coils is 5 (1 to 6) and the same amount of short-chording as in the case of the standard 28 slot armature, results. Thus the winding diagram will be a similar one but for 24 slots in place of 28 which had a slot pitch of 6 (1 to 7). We have made pictures of the various slots referred to which we attach for your information. EFC. | ||