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 on materials for H.T. distributor sparking points.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan301 | |
| Date | 22th September 1925 | |
| To R.{Sir Henry Royce} from EFC. c. CJ. HY.{Tom Haldenby - Plant Engineer} EFC6/T22.9.25. RE H.T. DISTRIBUTOR. Answering your R3/M15.9.25, experiments on distributor sparking points of various materials were made on the old 40/50 battery ignition and reported in our EFC6/T28.1.21. In these experiments we did not experience any signs of the production of nitric acid and the resulting corrosion, and therefore the experiment was a comparison of these materials purely as sparking points. It was decided at the time that in this direction tungsten was the best, but that nickel and stainless steel were quite good seconds; the other materials tried which came third were silver, nickel brass and nichrome. Tungsten is very difficult to work and is largely affected by nitric acid, and for these reasons it is not considered it would be worth while to attempt to use it. Taking all things into consideration, stainless steel appears to be the only other suitable possibility than nickel, and we therefore propose to put in hand stainless steel points for experiment. The silver points were much blackened and burnt away. Regarding your last paragraph we think it is certain that tracking is started by a film of conductive (acidified) moisture which is probably due, in the cases Contd. | ||