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).
Analysis of ignition coil performance, comparing the Goshawk and 40/50 engines and experimenting with different secondary winding turns.
| Identifier | WestWitteringFiles\I\October1922\ Scan62 | |
| Date | 28th October 1922 | |
| EFC1/T28.10.22. -5- Contd. circuit) in addition to their own, but it was found that with the amount of ballast which was judged in the first instance to be suitable, the phenomenon could be reproduced. It was further found that by reducing this additional ballast to a considerably smaller amount than at first considered, or by dispensing with it altogether, the ignition can be rendered absolutely unfailing under all circumstances. The conclusions drawn from these facts are that at any rate as compared with the 40/50, the ignition requirements of the Goshawk, no doubt owing to the higher compression, are greater than on the 40/50, being entirely only satisfactorily met/by the use of a coil of larger dimensions. Another line of experiment arising from the argument that possibly the number of secondary turns (21000) in use was not the optimum number to give maximum available breakdown potential with the capacity of the Goshawk leads as arranged, and that possibly by changing the number of secondary turns a larger breakdown potential would be secured, we accordingly tried a coil of 15000 turns on the secondary winding which had been built in connection with some previous tests on the 40/50 with reduced number of secondary turns. This particular coil, as a matter of fact, had run 10,000 miles on a EX and did not give any trouble, but judged from previous experiments on the 40/50 with series coils with various numbers of secondary turns, it had been previously decided | ||