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 Rotax and U.S.A. Bosch dynamo performance, construction, and cooling characteristics.
Identifier | WestWitteringFiles\F\March1921\ Scan42 | |
Date | 17th March 1921 | |
Contd. -3- EFC3/T17.3.21. It will be noted that the final output in each case is less than 9 amperes, so that these results are representative of what would happen if we endeavour at first to keep the output up to that specified above, being forced in the later stages of such a heating test, after reaching the peaky at 9 amperes, to continue on the peak at the lesser value. You will notice from these figures how much cooler the U.S.A. Bosch ran than the Rotax. For convenience we also attach comparative table of these two machines as regards performance and other details. So far we have not noticed the Rotax machine to be noisy, but in further running we will carefully watch this point. We do not know the exact winding of the Rotax dynamo armature, but this has 14 slots and 28 commutator bars. If a dummy coil were used, should we not expect this only to have 27 commutator bars ? On the other hand, the U.S.A. Bosch dynamo - which is a hand-wound armature with open-tunnelled slots similar to the R.{Sir Henry Royce} Bosch has 17 slots but 33 commutator bars. This would have suggested a dummy coil had it been a * former wound armature. We have not so far asked for another Rotax A.T.12 dynamo to be ordered owing to the necessity for economy, but have considered it advisable to await your instructions after seeing the performance we have to present. Contd. | ||