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).
Notes from further experiments on ignition coils, discussing different materials and failure conditions.
| Identifier | WestWitteringFiles\J\November1922\ Scan67 | |
| Date | 19th November 1922 | |
| EFC3/19.11.22. ADDITIONAL NOTES AS A RESULT OF FURTHER EXPERIMENTS. (1) Asbestos filled elo material is no better, but possible worse. (2) It is not considered that the fault is due to the filling material, but rather due to the resinous substance itself. (3) Marmon coil was run on Goshawk chassis for two hours without failure although made up in a bakelite case, but e internal construction is very different, there being a much larger space between the outside of the coil itself and the inside of the case. (4) In all tests a small external gap in the wire leading from the H.T. terminal of the coil to the central terminal of the distributor has been included, so as to render the sparks visible and this has added an increased resistance to be overcome by the H.T. spark. Coils in stabalite cases and coils outside their cases do not mind this extra gap. The consequence is they provide a good margin for this worst condition. (5) It seems very probable that a coil which has failed under these extreme conditions after one hour satisfactory runding would in ordinary running conditions be entirely satisfactory, though perhaps it is as well to avoid any risk. (6) The experiment with the 16000 turns coil with plenty of rubber between the outside of the secondary and the | ||