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).
Continued analysis of magneto performance, comparing different designs and timing mechanisms.
| Identifier | ExFiles\Box 48\2\ Scan483 | |
| Date | 29th March 1926 | |
| Contd. -5- EFCL/T29.3.26. further improve the slow running of the magneto, or at any rate make amends for any loss of slow speed performance in the retarded position due to making the break later, and thus improve the high speed performance. The amount by which the sleeves move the axis of flux round is roughly speaking two-thirds of their own motion (see second curve on diagram previously mentioned). Owing to the use of the sleeves, the advance and retard demand on the internal time functioning of the magneto is only 18° instead of 62°, † so that in any case from the point of view of the armature timing, they are at a big advantage as compared with other magnetos in the production of Contd. † A 60° range magneto of similar weight to the Watford has been submitted to us which, without the use of any sleeves, and with the break arranged considerably later in the advanced position, and therefore very considerably later in the retarded position, gives a retarded performance very nearly equal to that of the Watford, and an advanced performance at high speeds very much better. This would have appeared to us to have been impossible until we have actually observed it experimentally. The range demand on the internal time functioning of the armature is of course 60° instead of only 18°. It is of course appreciated that it has the advantage of having no second air gap. | ||