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).
Performance improvements and testing of magnetos with tungsten points.
| Identifier | WestWitteringFiles\T\2July1929-December1929\ Scan209 | |
| Date | 6th December 1929 | |
| -2- APC/ATR6.12.29 contd. It has been our firm conviction that Messrs. North could eventually produce an efficient magneto with tungsten points and we now have concrete proof in the shape of this magneto. Reducing the range at our suggestion from 66° to 60° by taking 3° off each of advance and retard, has certainly improved the electrical performance so much that the addition of tungsten points has not affected the performance appreciably. The leak performance fully advanced and the high speed figure fully advanced, together with the low speed figure fully retarded, have actually been improved. It now only remains to test the reliability of these contacts over a long endurance run to establish their supremacy over iridio platinum. This we are proceeding to do. See below. In regard to a W6A magneto No.116717 of 60° range and fitted with larger diameter platinum points, my assistant's report WD.{Mr Wood/Mr Whitehead}91. reads as follows :- "We have now tested this magneto on the bench to our general specification of performance for 40/50 HP. chassis magnetos. The results obtained were very good and the disposition of the advance and retard appears to be the optimum. A figure of 115 r.p.m. was obtained for the minimum slow speed 60° retarded. We have never yet tested a magneto with a 60° range with equal or nearly equal performance to that of this machine. Not only is the slow | ||