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).
Testing a magneto with automatic advance, including details on rotation, RPM ranges, and advance curves compared to a 20 HP chassis.
| Identifier | WestWitteringFiles\L\2April1924-June1924\ Scan42 | |
| Date | 31th March 1924 | |
| Contd. -3- EPCR/TS.D.24. The idea of testing this machine was the possibility of its application to the E.A.C., but for this purpose a magneto of negative or anti-clockwise rotation was required, and arrangements were accordingly made by which this magneto was returned and another, No.34937, of similar type but opposite rotation received. This possibility was referred to in HSR/LCL.2.24. It was asked on this machine for the automatic advance to commence at 300 r.p.m. and to be complete at 3300 r.p.m., attaining if possible two-thirds of the advance at half the total increase of speed. The advance characteristic of this machine when received was found to be in accordance with section of attached sheet/s dated 31.3.24, this being exhibited also as a curve on photostat herewith. The photostat curves were really drawn with reference to the 20 HP. chassis. It will be seen that the advance curves of the three magnetos vary considerably one from the other, but that generally they are nearer to the final advance curve required for the engine, plotted from figures supplied by EP.{G. Eric Platford - Chief Quality Engineer}, than is our own battery ignition. The total advance of which is really equivalent to 45° on the magneto. Contd. | ||