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).
Pros and cons of magneto ignition versus dual battery ignition for various chassis.
| Identifier | ExFiles\Box 163\7\ img217 | |
| Date | 5th December 1933 | |
| 63199. To W.O.R. from E.{Mr Elliott - Chief Engineer} E.10/HP.5.12.33. c. Hs.{Lord Ernest Hives - Chair} Dr. re Magneto Ignition. With regard to the discussion on magneto ignition which took place on the occasion of the last Conference held in Derby, the final conclusion seemed to be that what is desired is either double ignition or single ignition with a standby which can be brought into action very easily. Personally I am of the opinion that a standby ignition is of very little use unless it can be made available by the turning of a switch. We know from our experience with the 20/25 chassis that the standby ignition is in many cases not used when it is required due to the ignorance or inability of the driver. We have therefore made an effort on the SpectreCodename for Phantom III to get two sets of sparking plugs on the cylinders with a view to fitting dual battery ignition and although it is a little early yet to say that we have overcome all the difficulties we believe that we shall succeed in carrying this out. When it comes to dealing with a smaller unit than the SpectreCodename for Phantom III having 12 cylinders we may have to find some other solution. In the case of the Bentley chassis I feel that we shall eventually come to dual ignition but in the meantime we do not think a magneto on this car would be of very much use as it is not an engine that can be swung cold and in all our experience we have not found one case of any standard equipment failing to give a spark on the battery ignition in cases where the battery has been inadvertently run down or where any of the cells have failed by shorting. The point mentioned by BY.{R.W. Bailey - Chief Engineer} in connection with the disadvantage of the magneto is that since it is necessary to drive the magneto through the dynamo owing to the layout of the engine, the dynamo is compelled to run at a higher speed than is desirable, which has the effect of reducing the charge available for the battery, and reduces thereby the chances of the battery being kept fully charged. | ||