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).
Experiments investigating spark length in a chassis battery ignition system at various speeds.
| Identifier | WestWitteringFiles\D\January1920\ Scan35 | |
| Date | 20th January 1920 | |
| To R.{Sir Henry Royce} from Ck.{Mr Clark} c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Bn.{W.O. Bentley / Mr Barrington} c. to Da.{Bernard Day - Chassis Design} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to Ba. ORIGINAL X.3129 - CHASSIS BATTERY IGNITION X.3199 (A) Loss of Spark Length due to Seconda Variable Gap. (B) Spark Length at Various Speeds. We attach photostat curves showing the above two effects. These were taken on the bench with the R.R. chassis coil and distributor, with all quantities standard. We attach also a copy of my assistant's report on these experiments, upon which you will note certain conclusions in regard to (A). As regards the (B) portion, it is interesting to note that the maximum gap length increases at first with the speed of the contact breaker, and afterwards decreases. This may at first sight seem queer, but is no doubt due to the action of the ballast resistance. As the maximum voltage obtainable at the secondary gap depends upon the magnitude of the instantaneous current at primary break (supposing the smartness of break to be the same at all speeds), it will be seen that at the slower speeds, owing to the action of the ballast resistance, the current in the primary may actually fall, after its initial rise, due to the heating effect of the ballast, so that the current at break at slow speeds may actually be less than the current at break at moderate speeds. Contd. | ||