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).
Proposal to standardize Goshawk ignition coils by increasing their length.
| Identifier | ExFiles\Box 45\4\ Scan137 | |
| Date | 29th January 1923 | |
| XH079 To R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} from EFC. c. EY. c. Ey/Ds. c. Mr. Brock. c. EP.{G. Eric Platford - Chief Quality Engineer} EFC2/T29.1.23. X.4079 - GOSHAWK IGNITION COILS X3445 We are most anxious, irrespective of the material of the coil cases, i.e. whether bakelite or stabalite, to standardise ignition coils (the same for Goshawk and 40/50), with cores and cases 1/2" longer than at present, and would therefore first like to obtain your approval that all further experimental work on coils be carried out with this increase. The electrical argument is as follows :- We have so far in the unlengthened coils always used a 6-layer primary. In order to satisfy the condition that both ends of wire must be brought out at the same end of the coil, an even number of layers must be used, so that the next lowest possible is four. If, on our present standard size of coil, we drop to a four-layer primary, then in order to obtain the necessary magnetising effect without an uneconomical use of current, it would be necessary to reduce the size of wire to such an extent that the ballast resistance would no longer be a sufficient proportion of the present resistance of the circuit to have anything like the effect of reducing the current with the contacts left on, or levelling up the current consumption at different speeds. With an addition of 1/2" for to the length of the coil, however, the four-layer primary becomes possible with the same size of wire (300 turns), in which the ballast | ||