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).
Test report detailing the performance and endurance of a magneto under various conditions.
| Identifier | WestWitteringFiles\F\March1921\ Scan38 | |
| Date | 15th March 1921 | |
| Contd. -2- (6) Referring to the position when the armature flux is maximum for dead slow running as the datum position, we found that the make occurred 20° before and 18° after this position for the advanced and retarded positions respectively. The range we found to be 38° so that the points of break for the advanced and retarded positions were 53.5 and 91.5 in relation to the same datum, thus the make ratio, i.e. time of make / total period, is .407, corresponding to the equivalent of long wave. The primary platinum point gap we found to be .022". We found the above gap and timing to be immaterially altered in our running tests and the timing to be very little affected by varying the platinum point gap ± .004. (7) Results of short endurance test (12 hour) at 2000 R.P.M. sparking on a set of 5.5 mm. gaps in air with timing lever central - tracking was rather bad on the distributor cover. There were marks on the segments as if there had been sparking at the brush at break corresponding to the retard position. The Americanite contact breaker block appeared to be appreciably worn by this test. (8)&(9) Open circuit volt-speed and short circuit ampere-speed curves of the magneto primary are given on the accompanying photostat. (see follow) (10) The short test in which the magneto is run at 1500 r.p.m. for half a minute with timing lever central and secondary winding short circuited went through O.K. (11) The open circuit test in which the machine was again run at 1500 R.P.M. for half a minute with timing lever central and with the high tension terminal not connected to anything so that the secondary spark took place on the safety gap of the magneto, was also O.K. (12) The short test at 1500 R.P.M. for 15 minutes with timing lever central and the discharges taking place on 5.5 mm. gaps in air, with standard length, 2 ft., high tension cable as usual, was now taken to see if the machine was normally correct after open circuit test. It was found to be O.K. (13) Utility Test. Maximum gaps obtained on this magneto on the utility test were as follows :- (a) 5.0 mm. (b) 6.5 mm. (c) 4.5 mm. Contd. | ||