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 discussing a job applicant and the advantages of a nearly closed magnetic circuit ignition coil.
| Identifier | ExFiles\Box 169\2\ img032 | |
| Date | 13th May 1925 | |
| V/103! 11, Madeley Street, Derby. 13th May, 1925. Dr. E.C. Turner, 35, Mayfield Road, Moseley, Birmingham. Dear Dr. Turner, I have your letter of Monday with reference to Mr. M.J. Berlyn, who has already written about the possibility of a berth in my department. I regret I am not at the moment able to offer him anything, as at present I have my full complement of staff, but have put him on our list of enquirers with whom we communicate when a vacancy occurs. I notice you refer in your letter to a nearly closed magnetic circuit ignition coil. I have myself been thinking about this lately and I am taking this opportunity of asking you as to what you consider to be the real advantage of such a nearly closed magnetic circuit, as compared with the ordinary open magnetic circuit type coil. I have given a little thought to the matter though not yet perhaps so completely as it deserves, and in the first instance it appears to me the only advantage gained is on the score of size. I do not see how it enables one to gain materially in the overall electrical efficiency of the coil, particularly when a ballast resistance is being used in any case. In fact it appears to me that the only advantage in using an iron core at all, as compared with a large air cored inductance, is on the score of bulk. On the other hand I can see a definite disadvantage on going to the other extreme of a completely closed magnetic circuit. Therefore I should very much appreciate your view of the matter if it is not asking too much. Yours very truly, | ||