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).
Comparison between the Watford sleeveless type magneto and the Lucas type ERS magneto.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 176 | |
| Date | 13th June 1927 guessed | |
| -9- Contd. General remarks re comparison of Watford sleeveless type magneto and Lucas type ERS magneto. It would appear that the Lucas is the more normally arranged of the two machines electrically, i.e. its contact breaker and distributor timing are more like what would be expected on principle for the best general operation. It appears that this is possible because the capacity of the Lucas armature is greater than that of the Watford. The good low speed sparking result of the Watford in the retarded position (range 50° only) has been obtained by the use of very extended pole shoes and by improving the low speed retarded sparking at the expense of the high speed advanced sparking. Further, by :- (1) Having the centre of the variable range more advanced than in the Lucas. (2) Providing a smaller range (50° in place of 60°). The Lucas machine just misses our specification of low speed performance in the fully retarded position, but the Watford machine very much misses our specification of high speed and utility performance in the fully advanced position. It appears to us that the performance of the machine as it stands has largely been obtained by nursing, and that the more ordinary conditions obtaining in the Lucas magneto would be an advantage in the long run. Remembering that the instant of break in relation to the armature position of maximum flux is the same on the two machines, if we take the performance of the Lucas at the same degree of retard as the Watford, we find the low speed Contd. | ||