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 timing, the contact breaker, and the potential for an engine to run backwards.
| Identifier | ExFiles\Box 37\1\ scan 038 | |
| Date | 22th July 1918 | |
| -2- To R.{Sir Henry Royce} cont. range of 44° advance and retard on the crankshaft, corresponding to 22° ditto on the contact breaker. We will further assume, in the case of the jump spark distributor, that the revolving contact has a length of periphery about one third of the pitch of the stationary contacts. The equivalent of this in the wipe contact distributor case would appear to be that the stationary metal segments should be one third of their pitch long circumferentially. Considering the various cases in order, the results appear to us as follows:- (1) (a) Taking it that the contact breaker points open when A.{Mr Adams} The leading point of the periphery of the revolving finger is exactly opposite a stationary contact point. B. The brush has just commenced contact with a metal segment. Should the engine in running forwards at any time have insufficient inertia to carry it over the D.F. it appears that the rebound from the early explosion, caused by the normal forward running spark, might have sufficient strength to start the engine backwards. Under these circumstances sparks would be produced very nearly exactly on the D.F. running backwards, and therefore, if any explosive charge were contained in the cylinders, the engine might run back for a few revolutions. Apparently, this is the case you R.R.S.C.(100) (S.C. 1548) 19-12-11 S.E.R. | ||