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).
Magneto performance issues at low speeds, comparing various types and proposing revisions to production specifications.
| Identifier | ExFiles\Box 48\2\ Scan374 | |
| Date | 28th April 1928 guessed | |
| -2- The E.O.6. production specification limits of low speed performance are :- Advance 280 r.p.m. Retard 190 r.p.m. It appears therefore that the EW6 type magneto has insufficient energy at low speeds to satisfy our Phantom engine requirements, although it passes our General Specification. We therefore submit a revision of our general specification as follows :- Page 2, Clause 5. The speed limits should read :- "The magneto shall be capable of firing this special test gap with shunted leak regularly at a speed of 250 r.p.m. fully retarded and at a speed of 2500 r.p.m. fully advanced -----" Page 3, Clause 7. The low speed figures should read :- A. {Mr Adams} 280 r.p.m. B. 200 r.p.m. C. 170 r.p.m. We do not consider that this is asking for the impossible as Mr. has informed us that the Lucas ER6 magnetos which he has personally tested from time to time have been quite O.K. at starting the engine cold. The volt-ampere capacities of the armatures of the Lucas and Watford EW6 magnetos at 400 r.p.m. are :- Lucas 7.14 volt-amperes. Watford 5.02 " Corresponding figures taken on EO6 magnetos a considerable time back were 5.43 volt amperes, showing the EW6 magneto to be the lowest of all. EFC {E. Fowler Clarke - Electrical Engineer} / H.E.West. | ||