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).
Trials of spark length against cable length for different ignition coils.
| Identifier | ExFiles\Box 52\3\ Scan354 | |
| Date | 4th April 1920 | |
| X 2814 To R. {Sir Henry Royce} from EFC. {E. Fowler Clarke - Electrical Engineer} c. CJ. c. E. {Mr Elliott - Chief Engineer} c. to Bn. {W.O. Bentley / Mr Barrington} c. Da. {Bernard Day - Chassis Design} c. Hs. {Lord Ernest Hives - Chair} c. Oy. EFC {E. Fowler Clarke - Electrical Engineer} 2/T14.4.20. X.3199 - BATTERY IGNITION - GENERAL. X 2814 Further to our EFC {E. Fowler Clarke - Electrical Engineer} 1/T14.11.19, we have now made further trials of spark length-cable length curves for :- (1) Standard R.R. ignition coil under standard conditions and working at 50 S.P.S. (sparks per second) (2) Remy 6 cyl. 6 volt coil, also working at 50 S.P.S. The running current in the R.R. case was 1.05 and for the Remy case 1.25 amperes. The R.R. coil of course uses a much greater proportion of energy in the ballast resistance than the Remy, thus accounting for the fact that the Remy current is nowhere near twice as great as the R.R. current. It will be seen that the fall of spark length with cable length does not follow any regular law but seems to go in a sort of wave, due perhaps to resonant action in the cable, especially in the case of the Remy. This point was referred to in our previous memo EFC {E. Fowler Clarke - Electrical Engineer} 1/T14.11.19. The results given therein were not intended to be strictly comparative but just to show the general effect of increase of length of cable. The somewhat poor and inconsistent results obtained on the R.R. coil then tested may have been due Contd. | ||