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).
Letter to a supplier regarding testing and safety gap requirements for aero magnetos.
| Identifier | ExFiles\Box 43\4\ Scan286 | |
| Date | 17th May 1930 | |
| Messrs. North & Sons, Ltd. Whippendell Rd. Watford. 17th May, 1930. -2- of the B.T.H. magnetos. In this connection we enclose a copy of a note written to Mr. Jacques of the A.I.D. here pointing out the desirability of this change and reminding him of the fact that the magneto so arranged had duly passed the type test. It will be remembered that we were, when your Mr. Allen returned from his last visit to us, in progress of carrying out a 100 hour test on a similar magneto No. 83132 with the distributor open-circuit and the high tension discharges passing across the safety gap continuously, this gap being set to 8.5 mm. with a view to stressing the armature insulation. This test has now been completed and has demonstrated that the armature insulation will stand up to these increased voltage conditions. The only weak place elsewhere on the high tension circuit is apparently the H.T. rotor and fan. At the beginning of the test we had to replace these units due to a breakdown occurring along the surface of the rotor spindle insulation. We would like, if possible, to be assured that all further aero magnetos delivered to us shall have safety gaps set to a minimum of 8.5 mm. In order that you may check the condition of this other magneto No. 83132 we are arranging for the return of this also. Yours faithfully, FOR ROLLS-ROYCE LIMITED. Copy of memo enclosed. | ||