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).
The bench testing and analysis of various ignition coil designs, noting differences in insulation and secondary wire.
| Identifier | WestWitteringFiles\D\April1920\ Scan3 | |
| Date | 13th April 1920 | |
| Contd. -3- EFC2/T13.4.20. maximum gap length for regular firing and the number of secondary turns, from which it will be seen that this maximum is roughly proportional thereto. The running currents were approximately the same for the different coils at all speeds, but if anything, higher the fewer the number of secondary turns. Coil E.12 has not yet been completed as there was delay in obtaining the secondary wire. In coil E.18 there is increased insulation at the ends of the layers but not between layers. In coil E.14 the insulation was as standard, the increased gauge of wire making up for the fewer turns. In coil E.12 the insulation was, if anything, a little less than standard, but relatively more owing to the decreased voltage; and the same would apply to coil S.10. No effect on the bench tests of the increase in section of the secondary wire in the form of increased thickness of initial spark could be appreciated. To all appearance the effect was merely as if due to reduced number of turns and not to any other cause. To complete investigations of these coils it will be necessary to compare them on an experimental car changing only from coil to coil. It does not appear that anything further can be done, in the matter of bench tests, but if you can suggest anything, we should be pleased to carry this out. R.R. 235A (100 T) (S.F. 846. 6-8-19) EHC | ||