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).
Coil insulation materials and sparking plug experiments for the Goshawk engine.
| Identifier | WestWitteringFiles\J\November1922\ Scan15 | |
| Date | 11th August 1920 | |
| (2) the amount of any known material the better; and metal out- side the insulation would be disastrous. There seems little to choose between stabilite and ebonite and pure rubber, and par- affin wax. Of these the only one mechanically suitable appears to be stab- ilite. Assuming then that this material is as good as any Records would suggest that a fair air space be left between a bakelite case and the coil. We can therefore only conclude that the space is no use except to keep the secondary wire away from undesir- able materials, so that the best coil would be one that was surrounded on the outside and at the ends by air only, all the metalwork being as far as possible away. Assuming that this is not practical, the smaller the amount of any material, the better. An experiment I would suggest would be to use bakel- ite ends and cover, central L.T. wires, and a tube of various materials carrying the H.T. connections. This tube must be mechanically strong and capable of standing heat and moisture. I cannot think of any material that we can use, or any design that can be adopted for the coil that is more suitable than stabilite, if this material is found to be as good as any other material for electrical efficiency. In the Goshawk we use high secondary electromotive force, because EP.{G. Eric Platford - Chief Quality Engineer} likes plugs with wide gaps, and the compres- sion pressure in this smaller engine is higher than in the 40/50. It is possible however that owing to a heated or oxidized condition of the sparking plugs points, the margin of electromotive force is not high, and I suggest in the experi- ments that cooler working plugs are tried or plugs with platinum points, or that during experiments the points are cleaned from any oxidized effect. It will be noticed also that the higher | ||