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).
Various performance tests conducted on a magneto, including sparking characteristics and resistance measurements.
| Identifier | WestWitteringFiles\F\March1921\ Scan49 | |
| Date | 18th March 1921 | |
| Contd. -3- EFC3/T18.3.21. 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) 6.6 mm. (b) 6.6 mm. (c) 6.0 mm. (d) 6.0 mm. The spark length therefore does not fall off materially due to leakage paths. 14. A range of advance and retard at 34° was now arrived at, as described in our EFC4/T3.2.21, the selected position of break at full advance being 10° earlier than the makers, and that for full retard being 21.5° earlier. 15. High speed sparking characteristics. Regular sparking took place at all speeds 1500 to 3500 R.P.M. with lever in all positions on gaps not larger than 6.6 mm. Shorting any one gap affected the following spark at speeds above 2500 R.P.M. at advance, otherwise no effect. 16. Low speed sparking characteristics. The lowest speeds for regular sparking on 5 mm. gaps in air for advanced, central and retarded positions (on our range) were found to be 244, 192 and 220 R.P.M. respectively, indicating that in advancing the range we have arrived at a lower low speed sparking result for full retard. Owing to the irregularity of the gaps on the two sides, the above results can only be obtained approximately. 18. Primary resistance .76 ohm at 14°C. 19. Secondary resistance 2690 ohms at 16°C. 20. Milli-amperes taken by secondary winding at 108 volts 50~, Maximum 22.4 (armature horizontal) Minimum 16.3 ( " vertical ). (upside down text at bottom) R.R. 285A (100 T) (S.H. 10-12-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2947 EFC. | ||