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).
The preliminary bench testing of Watford IS12 aero magnetos.
| Identifier | ExFiles\Box 43\4\ Scan218 | |
| Date | 3rd February 1930 | |
| E.7.C X4021. X.NO. 3832. 4021. REF. NO. W.E.1. DATE 3-2-30 Watford IS12 aero magnetos. We have now tested preliminarily on the bench magnetos Nos 98033/4 of the above type prior to these being fitted to a type test 7 engine. The electrical test consisted of running these magnetos with 6 feet long metal braided H.T. cables (earthed at each end to the magnetos) coupled up to 5.5 m.m. third point discharge gaps for 1 hour at 2500 r.p.m. fully advanced, followed by observations of high and low speed sparking. Both these magnetos have a tendency to misfire in the extreme positions of advance and retard particularly No 98034 which regularly misfired at all speeds in these two positions. The low speed sparking, which is generally a good indication of the quality of electrical performance, was also poor on this magneto. We tested another IS12 magneto | ||