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).
Magneto and battery ignition systems for engine starting and performance.
| Identifier | ExFiles\Box 37\1\ scan 014 | |
| Date | 26th April 1917 | |
| R.R. 233A (500 T) (S.D. 408. 26-4-17.) Bm. 2/156/13. Contd. EH3/LG171017. broken by retarding the lever, this would allow us to strat up after the propeller had been turned round by hand. The extra range on the battery ignition would be sufficient to always be certain of breaking the contact points on one of the ignition sets. X.2375 Since writing the above we have received Mr. Elliott's note E5/W151017. It appears to be rather extravagant to carry such a heavy, costly and complicated piece of mechanism as a hand magneto, for the chnace that the battery might run down. Would it not be better to carry some small dry cells, they would only be needed just for strating so that they could be very small and light. If the hand magneto is to be carried for starting with the propeller that would be used. We should still like to be able to retard the battery ignition more than the magneto because it is possible to get better slow running with the ignition firing late. The range on the Watford magneto is 25°. The magneto is set so that it fires 35° B.D.P. when advanced, soathat it is 10° B.D.P. when retarded. We had some Watfords lately where the range was only about 20°, but we have had permission to increase them to 25° because the slow running was worse. EH. | ||