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 and suggestions for the Phantom automatic ignition advance mechanism.
| Identifier | WestWitteringFiles\O\January1926-March1926\ Scan119 | |
| Date | 11th March 1926 | |
| TO HS.{Lord Ernest Hives - Chair} & E.{Mr Elliott - Chief Engineer} FROM R.{Sir Henry Royce} C. to CJ. BJ. RG.{Mr Rowledge} WOR.{Arthur Wormald - General Works Manager} DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} ORIGINAL R2/M10.3.26. 4-0 11/3/26 X8685- X8790- PHANTOM AUTOMATIC IGNITION ADVANCE. Experiments being made at Derby shew insufficient margin of power on the relay hydraulic motor. (1) You will remember that I have suggested the use of a retarding spring on the magneto cam rocker instead of friction to keep the controls quiet. This scheme has never been properly arranged on test, as far as I know. It would result in the spring over the motor piston being less in force, and would leave the motor with less work to do, or a greater margin of safety, the only question about it being - will it keep it quiet, and will it affect the controls. The spring should be effectively the same force as the friction, and would result in the opposing force of the spring over the motor being reduced twice this amount. My memory says the friction was 3 lbs. each way so that the opposing spring would be reduced 6 lbs., because there would be the 3 lb. spring trying to retard the magneto against no additional friction, which is 3 lbs. So that the motor has to lift 3 lbs. less. (2) Again, the governor at the zero position should be set to advance the ignition as soon as the oil pressure exists say one tenth to one fifth of its total amount, because if the engine is running at all it will stand this advance. This is the way to cater for the lag remarked about - i.e. the piston valve never goes right back to zero, but is set to admit oil under the piston as soon as the oil pressure exists, and before the governor moves it lifts the piston 10 to 20% of its stroke. R.{Sir Henry Royce} | ||