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).
High and low-speed sparking characteristics, resistance, and noise levels of a magneto.
| Identifier | WestWitteringFiles\F\March1921\ Scan39 | |
| Date | 15th March 1921 | |
| Contd. -3- EFC1/T15.3.21. These may be compared with the results for the Bosch machines and Watford machines given in our EFC4/T3.2.21. It will be seen that the spark length falls off much more rapidly due to leakage paths in the case of this magneto than in that of those others. (15) High speed sparking characteristics. At all speeds over 1200 revs. up to 3200 revs. with lever in all positions regular sparking was obtained on 8.5 mm. gaps, the sparks being equal and unaffected by shorting any one gap. (16) Low speed sparking characteristics. The lowest speeds for regular sparking on 5 mm. gaps in air for advanced, central and retarded positions we found to be 180, 180 and 185 R.P.M. respectively, showing little or no variation due to contact lever position. There would be no particular advantage in selecting any particular 34º out of the available 38º of range provided by the makers, as in the case of other magnetos. (18) Primary resistance .68 ohm at 16ºC. (19) Secondary resistance 3455 ohms at 16ºC. (20) Milli-amperes taken by secondary winding at 108 volts 50~. Maximum 12.3 Minimum 8.4 As regards the noise of this machine, we noted that there was a loud ticking noise made by the contact breaker, but otherwise the machine was fairly quiet. EFC. (upside down text) R.R. 285A (100 T) (S.H. 79S. 10-12-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2947 | ||