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).
Methods to improve dynamo output by modifying the armature without increasing its dimensions or weight.
| Identifier | ExFiles\Box 163\6\ img140 | |
| Date | 7th February 1931 | |
| X6016 To Wor.{Arthur Wormald - General Works Manager} from EFC. (2 copies) EFC1/AD7.2.31. X.6076. DYNAMO OUTPUT ETC. X.6099 X.6016 Referring to your query (through Mr. Tonge) as to what we are doing "in order to obtain still more satisfactory results" (Sg{Arthur F. Sidgreaves - MD}'s memo Sg{Arthur F. Sidgreaves - MD}3/k23.1.31), we would say firstly that the two-rate charge scheme is good in principle provided we have a generator of sufficiently early cutting in and sufficiently great output at speed. We know of only one means whereby the performance of the machine may be simultaneously increased in these ways without increasing its dimensions and weight and that is in the idea we have recently evolved of, instead of cutting away the pole pieces either concentrically or in a tapering manner, (which incidentally only increases output at the expense of cutting in point and vice versa) introducing equivalent "magnetic reluctance" into the armature itself by widening and deepening the slots so that the increase of reluctance will be made at a place where it is definitely useful in another direction, namely, increasing the size of the copper armature conductors and thus enabling the armature to deliver more current for a given degree of heating. We are confident that by this means we shall obtain a result which is an improvement on any previous result with the present weight and dimensions of dynamo and we are hopeful that the improvement will be considerable. A Phantom II armature so rearranged is nearly ready for our experimental test. We have also asked for the instructioning of a 20/25 armature as per copy of EFC1/AD6.2.31 attached.) Apart from the above idea there is the possibility of increasing the armature diameter slightly at the expense of carcase thickness, this would alter internal dimensions but not weight appreciably and would almost certainly give us the expected small increase in output without interfering with dynamo interchangeability. | ||