Sparking faults and magnetic leakage in two magnetos returned to Messrs. Norths for investigation.
| Identifier | ExFiles\Box 43\4\ Scan017 | |
| Date | 30th November 1926 | |
| Contd. -2- EFC {E. Fowler Clarke - Electrical Engineer} 5/T30.11.26. We are now again handing you these two magnetos Nos. 83134/5 as it was requested by Messrs. Norths that they should be returned to them. In the meanwhile we have a report that so far the new magnetos brought up by them are going very well on the engine. We shall be pleased to know whether Messrs. Norths have decided as to why we obtain on test only every other spark in the advanced position. They will remember it was suggested that the general poorness of sparking in the advanced position was probably due to the contact gap becoming wider owing to burning away due to the presence of oil, but we are informed by our testers that they had, on subsequently having these machines on the engine, made the gaps correct, and yet could not obtain the correct sparking in the advanced position. In regard to the magnetic circuit of these IS.12 machines, upon examination of this on one of these magnetos (having taken out the rotor) it appears that there may be a considerable amount of magnetic leakage of flux between the top ends of the permanent magnets and the laminated side limb of the armature core. One would think that with the non-magnetic gap between these members should have been considerably greater than is actually the case, and we would like to hear Messrs. Morth's remarks on this point. In respect of our last para. on the first-page, [Handwritten: EFC {E. Fowler Clarke - Electrical Engineer} ] we query [Handwritten note in right margin]: Whether the spigot mounted magnetos need any provision for oil at all on the magnetos themselves. What do they say? | ||
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).