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. discussing requirements for magnetos on 12-cylinder aero engines, specifically regarding automatic advance mechanisms.
| Identifier | ExFiles\Box 43\4\ Scan100 | |
| Date | 1st December 1927 | |
| X4021 Ra EFC2/T. 1st. December, 1927. Messrs. North & Sons Ltd., Whippendell Road, WATFORD. Dear Sirs, With further reference to magnetos for our aero engines and partly in answer to your CHK/DEW.1. of the 29th ult., we wish now to state that we could not consider the use of any type of centrifugal automatic advance, or of any type of automatic advance which necessitated the provision of one for each of the two magnetos of an engine; such apparatus is ruled out entirely by various considerations. Therefore we wish again to say that it is most necessary for the good functioning of our 12-cylinder aero engine to have magnetos provided electrically with a 30° range, and we sincerely trust you will be able to look into this matter to see what can be done. As a further proposal which may materialize in the near future, we ourselves may produce a form of mechanical advance of the drive applicable to both magnetos simultaneously which may either be hand operated by interconnection with the throttle, or not impossibly may be operated by some kind of oil relay scheme similar to that which we have at present for advancing the magneto and battery ignition on the car. What we are anxious to know from you in this connection is what reduction of weight and dimensions (especially the length dimension) you can give us on a magneto if you had to provide no range at all, but only a spark at each of four fixed points of the rotor rotation. It would appear to be possible to have a very much smaller and lighter magneto and our object in putting this query to you is to have some idea of the weight saved which we could legitimately put in to the advance apparatus proposed. To put the matter colloquially "If we give you something, viz. the whole advance and | ||