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 of maximum gap tests and sparking characteristics for various magnetos.
| Identifier | WestWitteringFiles\F\February1921\ Scan82 | |
| Date | 1st February 1921 | |
| Contd. -7- EFC4/T3.2.21. The maximum gaps (mm) obtained on the two Z.R.6 magnetos and a Watford E.6 were as follows :- (a) (b) (c) (d) Safety gap. R.Bosch. 8.5 8.3 8.1 5.0 9.9 U.S.A. Bosch ZR6.7.6 7.2 4.3 4.2 8.7 Watford E.6 5.0 4.75 4.25 3.5 6.85 It will be seen that the R.{Sir Henry Royce} Bosch gave the longer regular sparks in all cases, but the falling off of spark length with added leakage was about the same. The investigation of the U.S.A. B.6 was not continued owing to the failure of this machine. The utility test has only recently been included in our schedule and has only been carried out on one Watford (E.6) magneto, as described in our EFC2/T7.1.21, the conditions being the same, namely, 1500 R.P.M. (14) The low speed sparking characteristics working to the makers ranges were now taken, those on the B.6 having been already taken before the failure on the open circuit test. The lowest speeds for regular sparking on 5 mm. gaps in air for advanced, central and retarded positions were found to be according to the following table in which the results obtained on the Watford magnetos are also included for comparison :- Contd. M E: 332v (100 L) (R H 388 10-IS-20) C s041 | ||