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).
Modifying the 20 HP magneto's specified range by using short cobalt magnets.
| Identifier | ExFiles\Box 57\2\ Scan239 | |
| Date | 13th December 1927 | |
| EFC1/T13.12.27. -2- Contd. The present specified range for the 20 HP. magneto is 58°. If we could have this figure reduced to say 40°, then we think that a magneto with the short cobalt magnets, similar in appearance to the present 20 HP. type, but made inexpensively without a sleeve, would be a workable proposition and give the necessary low speed retard performance. To obtain equal performance without a sleeve and with the present range, as explained in EY4/H17.5.27, almost necessarily means utilisation of a horseshoe type of magnet. EFC. | ||