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 performance curves and outputs for Rotax, Smith, and Lucas dynamos.
| Identifier | WestWitteringFiles\E\November1920\ Scan55 | |
| Date | 17th November 1920 | |
| Contd. -3- EFC1/T17.11.20. performances on the same sheet on which the performance of the Rotax is shown hot and cold. We have also drawn on this sheet our specified performance for any dynamo for the R.R. car. Regarding the performances of Smith and Lucas dynamos shown, these are the averages of three independent experimental curves, but it should be stated that in the case of the Lucas these were taken on dynamos with the control brush in the makers' original position and not in the somewhat retarded position in which we now receive them with the object of reducing the singing of the machine to a more reasonable amount. The output of the Rotax machine will be seen to rise to a maximum very rapidly and then fall considerably. If the curve found for cold performance represented the performance hot, we should say that this was quite a desirable form of out-put curve, but we think it will be agreed that, taken all round, the output of the Smith 3D is, for an inherently controlled machine, the best that we know by a considerable amount. X.4030 Curves of the field currents of the Rotax dynamo are given, showing how this current drops away as the speed increases. The Rotax dynamo may have a slight advantage as regards efficiency owing to not having xx excited coils in opposition and to the fact that the field current is reduced as the speed increases. We shall shortly have results to issue for the U.S.A. Bosch dynamo which is controlled similarly. EFC. | ||