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).
Analysis of ignition system spark characteristics with varying capacitor values.
| Identifier | ExFiles\Box 52\3\ Scan301 | |
| Date | 11th December 1917 | |
| R.R. 235 a (100 Ty) S.F. 846 6-8-19. G. {Mr Griffiths - Chief Accountant / Mr Gnapp} 2469 -12- EFC {E. Fowler Clarke - Electrical Engineer} 2/T11.12.17. Contd. effect increasing, for the spark is certainly more of the second type (b) p.3., and it is difficult to imagine the spark at break increasing. We have observed the spark at break and the spark at make independently on Remy 6 contact breaker by means of vision through apertures in a revolving disc, and we find that whereas the former is decidedly reduced by increase of capacity above normal the latter seems to remain constant. Addition of capacity above the normal reduced the available secondary voltage until when the capacity was trebled, the secondary spark would not jump an 8mm. gap regularly. At the same time the characteristic noise of the spark altered to a deeper tone. Mathematically the amplitude of the current oscillation composing the spark increases somewhat, but the frequency number is lowered. It was observed that although the time of the spark changed, the intensity seemed to be maintained. We have verified that the capacity of the 12 cylinder Remy condenser is rather greater than that required to reduce primary sparking to a minimum. This was confirmed by experimentally trying smaller capacities. Starting with no capacity, the addition of only a slight amount at once begins to reduce the arc at the points and improve the secondary spark. Even a high tension condenser of capacity 600 centimetres (= .00067 mf) produced a noticeable improvement in the secondary sparks. Various capacities less than that | ||