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 to reduce energy output in ignition coils, considering ballast resistance and finer windings.
| Identifier | ExFiles\Box 45\4\ Scan287 | |
| Date | 20th May 1925 | |
| To R.{Sir Henry Royce} from EFC. c. CJ. c. Ev.{Ivan Evernden - coachwork} X4079 EFC2/T20.5.25. RE IGNITION COILS. X4079 X8710 X4653 X4654 Reference your RL/M11.5.25, now that our ignition coils are consistently satisfactory from the point of view of material of case and consistent output performance, it may be possible to reduce the energy output. With this in view, we intend making experiments with (1) Additional ballast resistance. (2) Coils with finer primary windings than at present. We have asked for coils to be instructed experimentally with 24 SWG and 25 SWG in place of the present standard 22 SWG. As regards coils with nearly closed iron circuits, it is difficult to see any reason in principle why these should be an advantage. The only obvious advantage of a coil with an iron core at all appears to be on the score of size of the coil. We have, however, an expression of opinion from Dr. E.O. Turner of the Lucas Company, who apparently patented a coil of this type in 1922. We are endeavouring to obtain copy of this patent specification. He says that he does not think he would say the same to-day as he said in that specification, but that he does think there must be an advantage in the nearly Contd. | ||