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 Messrs. North & Sons, Ltd. concerning magneto rotor dimensions and performance issues.
| Identifier | ExFiles\Box 43\4\ Scan235 | |
| Date | 19th February 1930 | |
| Messrs. North & Sons,Ltd. Whippendell Rd. Watford. 19th February, 1930. -3- In regard to the question of rotor dimensions we wrote you on this matter and you sent us in return a blue print copy showing the distributor timing. We have also ourselves made observations from which we agree that there just is the necessary overlap in both the advanced and retard positions. We are however, still inclined to think that it would be advantageous to increase this overlap slightly by increasing the width of each of the 12 segments in order to make certain of sufficient margin for irregularities in manufacture and inaccuracy of distributor timing. In regard to the pair of SP.{Mr Spinney}12-2 screened magnetos Nos.98033/4 one of which namely No.98034 was recently returned to you with a complaint of imperfect performance in the fully advanced position, this magneto was returned by you with your Mr. Allen and is now, with magneto No.98033 about to start engine type test. We were satisfied on bench performance that the high speed performance of this magneto was improved, though we were not too well satisfied with the low speed performance this not being quite as good as that of No.98033. It is, as expressed to your Mr. Allen in conversation, our general impression that the performance of these aero magnetos is still capable of improvement by suitably re-proportioning the quantities of the armature and the sizes of the magnets,and working to a larger safety gap. Yours faithfully, FOR ROLLS-ROYCE LIMITED. | ||