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).
Reliability and testing of Watford magnetos based on a report from the Air Board.
| Identifier | ExFiles\Box 182\M21\ img013 | |
| Date | 1st May 1917 | |
| To EH.) from R.{Sir Henry Royce} Oy.) c. to J.{Mr Johnson W.M.} ORIGINAL X.2375 Re Watford Magnetos. X.2753 I understand from the Works that there are doubts about the reliability of the Watford magneto. We have received a letter from the Air Board saying " that two Watford magnetos were taken at random from stock, and the Faraday house people were instructed to test them for all speeds. Faraday House report that both machines spark regularly at 49 revs. per minute in the fully advanced position across a 3.5 m/m gap, and run without missing at all speeds up to 9,000 revs. per minute. Runs were made at 6,000 and again at 9,000 revs. per minute. No missing occurred at any speed, no sparking was observed at the platinum points, and the contact breaker showed no signs of wear or damage at any point." They have omitted to say how long the test lasted. FHR. R.{Sir Henry Royce} [Handwritten note] * 18000 sparks per minute: I doubt if it actually ran this speed and how they knew it was sparking. Correct, the only way is to make it fire an engine. | ||