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 and specifications for a number of special ignition coils.
| Identifier | WestWitteringFiles\D\April1920\ Scan1 | |
| Date | 13th April 1920 | |
| H-N Chassis 3EX. COPY [struck through] ORIGINAL To R.{Sir Henry Royce} from EFC. c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Bn.{W.O. Bentley / Mr Barrington} c. to Da.{Bernard Day - Chassis Design} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to Hs.{Lord Ernest Hives - Chair} X.3775 - RE SPECIAL IGNITION COILS. We have now made experiments on the bench on a number of special experimental ignition coils, the particulars of which are given in the following table. Reference. | Number of secondary turns. | Insulation of wire. | Bare diameter. | Covered diameter. ---|---|---|---|--- E.18. | 18,000 | Enamelled. | .0035 | .0045 E.16 | 16,000 | Enamelled. | .0035 | .0045 E.14. | 14,000 | Enamelled. | .0045 | .0055 S.R.14. | 14,000 | Silk enamelled. | .0035 | .0055 E.12. | 12,000 | Enamelled. | .0055 | .0070 S.12. | 12,000 | Silk enamelled. | .0035 | .0055 S.10 | 9140 | Silk covered. | .0060 | .0090. The only variation from standard in these coils is in the secondary winding. The two coils E.16 and S.R.14 were made previous to your note R1/C30.12.19, asking for further experiments to be made. These coils gave moderately good results on ordinary bench test (passing our production test for standard coils, although not being quite as good for sparking distance as the average standard coil), after which coil E.16 was fitted to 2 EX for the Contd. [Upside down text at bottom] R.R. 235A (100 T) (S F.{Mr Friese} 846. 6-8-19) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2460. | ||