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).
Development of a single coil battery ignition system for the 'Condor' engine.
| Identifier | ExFiles\Box 37\1\ scan 027 | |
| Date | 24th April 1918 | |
| R.R. 526 a (400 T) (S.C. 526. 16-2-18) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1545. To EFC. from R.{Sir Henry Royce} copy to CJ. X.3199. X.3292. RE BATTERY IGNITION. 24th April. 1918. R2/G24418. X.3296 Thank you for your memo EFC3/T20.4.18. re battery ignition. Owing to the fact that we are now able to obtain twelve-cylinder magnetos for the "Condor", we have decided to attempt to produce a battery ignition suitable for running all the twelve cylinders of this engine with one coil. We are doing this because of the smaller number of parts, and because we are less likely to get wrong in synchronising. It will be necessary, however, for this engine to run safely over 2,000 r.p.m., which may be considered its over-speed revolutions. It will therefore have to give 12,000 sparks per minute, and as the contact maker will break the circuit for, say, a third of the time, the time of the make will be 1/18000 part of a minute, or 1/300 of a second, and this will be the time for the current in the coil to grow from nothing to a sufficiently large amount to give a satisfactory secondary electromotive force. Regarding the primary winding and condenser for such a coil, it would appear that the winding would require to be coarser so that the back electromotive force, due to self-induction, would be less, if so, also the condenser would have to have a larger capacity; in fact, the whole thing appears to be exactly like a six-cylinder coil intended for six-volts but used with 12 volts and a greater non-inductive ballast. (CONTD) | ||