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).
Experiments with high-speed contact breakers and alternative magneto designs for aircraft engines.
| Identifier | ExFiles\Box 36\3\ scan 028 | |
| Date | 11th May 1917 | |
| To 'COPY' from R.{Sir Henry Royce} '1946' c. to J.{Mr Johnson W.M.} c. to EH. c. toWor for Mr. Ellis. X.3031 R5/B11.5.17. X.2823 - Re High Speed Contact Breaker Experiments. With reference to the above, I sent you a long telegram on Wednesday night which I hope has made the matter clear from my point of view, which seems to suggest that there is no reason why this contact maker should generate much more heat than the long cam Bosch type. It has occurred to me that from a rise of temperature point of view the smaller magneto might be preferable, and considering the high speed at which we are going to run it, it should fire the engine quite slowly enough. Mr. Elliott points out that the smaller magneto would have the advantage of fitting in closer than the present standard, which would be an advantage to the aeroplane builder, and it would not require such heavy brackets to support it. They would be smaller and could be (X.3031) lighter in design and made of Magnaalium, which we suggest would be a very suitable metal for the present standard brackets, if it would show a saving in weight. It has occurred to me that considering the trouble you are experiencing with the high speed contact breaker due to the centrifugal force and other reasons for heating the magneto, it might be preferable to use a sleeve type of magneto as we understand that these have been successfully made by the British Thomson Houston Company and are being applied to some engines, probably with an advantage in saving of weight, over [handwritten] double magnetos, as there seems no difficulty about these magnetos at present firing 8 cylinders at 1600 revolutions. | ||