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).
Letter to North & Sons Ltd. regarding a modification needed for Watford Aero Magnetos due to an issue with the distributor range.
| Identifier | ExFiles\Box 43\4\ Scan215 | |
| Date | 1st February 1930 | |
| X4021. c. Rg.{Mr Rowledge} c. Mailing. EFC2/AD. 1st February, 1930. Messrs. North & Sons,Ltd. Whippendell Rd. Watford. Dear Sirs, Watford Aero Magnetos. Effect on distributor of change of range from 15° to 30° Having noted in some instances a tendency for the H.T. spark to take the safety spark gap route, it has occurred to us to query whether the distributor segments were increased to accommodate the increased range, and upon investigation we find that apparently this has not been the case. A range of 30° (as at present) on the magneto is an equivalent of 20° on the engine. This is 1/36th part of an engine cycle, and therefore 1/3rd. of the distributor pitch. It is clear that each distributor segment does not cover the distance equal to 1/3rd of the pitch of those segments, whence it appears that either at full advance or full retard or both, the distributor rotor sparking point cannot be exactly opposite a portion of a distributor segment. We are of the opinion that a modification here is needed in order to realise the best performance of these machines. Awaiting your remarks with interest, we are Yours faithfully, FOR ROLLS-ROYCE LIMITED. | ||