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).
Ignition coil experiments, comparing different turn counts and insulation materials like bakelite and asbestos.
| Identifier | ExFiles\Box 45\4\ Scan067 | |
| Date | 19th November 1922 | |
| Contd. -8- EFC1/T9.11.22. unwise to go below 18000. We did, however, have an 18000 turn 40/50 coil on chassis 8-EX during the 10,000 mile test and it may be considered that such a coil is satisfactory (our present standard having 21,000 turns). Our first experiment with 18000 turn coil with rubber sheathing between the secondary and the bakelite has not been entirely satisfactory, but we intend to experiment further with a 16000 turn secondary and possible with a reduced gauge of primary wire and fewer layers of primary winding, so as to give more room for this insulation. Another experiment will be the use of a case moulded from asbestos filled Elo material in place of the more ordinary wood filled. It has now been confirmed that the coil case made of American bakelite powder, though possibly slightly superior to the Alo material, nevertheless is not as good as the mouldensite. E.F.C. EFC. | ||