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).
Critique of a sleeve inductor type magneto design (Paynes Patent), comparing it to polar inductor types.
| Identifier | ExFiles\Box 4\5\ 05-page056 | |
| Date | 9th May 1919 | |
| To En. From EFC. EFC2/T9.5.19. X.480. Magnetos General. (Paynes Patent) Regarding the attached, we do not think very much of the idea. The magneto is, in principle, very much the same as the sleeve inductor type magneto, and would suffer from the same defects. One of these is that there are necessarily 4 air gaps which do not admit of being cut down to very fine limits. This means that the size and weight of the magnet required would be comparatively larger, and would add to the cumbersomeness of the whole machine. The sleeve inductor of a magneto of such a type by virtue of its design, is a very difficult component part to manufacture, and it does not admit of the accuracy of its competitor, the polar inductor. It is quite true that in the polar inductor type of magneto, there are four air gaps, but by virtue of the greater massiveness of the inductor, these gaps (and particularly two of them) can be cut down to the utmost limit. The number of lines of induction driven across an air gap by a permanent magnet must vary within limits inversely as the length of the air gap, this case indidently is quite different from that in which the magnetisation is carried out by an electro-magnet, in which case, if the air gap was doubled, it would not halve the flux. It has often occurred to us that a multipolar inductor magneto might be constructed and made to work satisfactorily, but it is doubtful whether any material advantage would be ultimately gained over ordinary types of magneto. In any case, we should say that a multipolar polar inductor type would be Contd. | ||