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).
Letter to the Air Ministry detailing the technical requirements for a double spark 8-cylinder magneto for the Eagle XVI engine.
| Identifier | WestWitteringFiles\N\2July1925-September1925\ Scan112 | |
| Date | 30th September 1925 | |
| COPIES TO:- [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] "ELMSTEADHenry Royce's home in West Wittering", WEST WITTERINGHenry Royce's home town. CHICHESTER. 30th. Sept. 1925. Col. L. F.{Mr Friese} R.{Sir Henry Royce} Fell. Room 609. AIR MINISTRY. Adastral House Kingsway. W. C. 2. U R G E N T. My dear Col. Fell, Y430 Referring to our discussion on magnetos when you were down here, it was agreed that every effort should be made to obtain double spark 8 cyl. magnetos for Eagle XVl., as the resulting saving in weight, complication, and space, would be so great. It is hoped that such a machine could be designed on the lines of the Watford Inductor, of which we have a print, mounted on the standard 3 bolt flange with 90mm. spigot. It was decided that the magneto itself could have fixed ignition, and provision is made in the drive to provide a retarded position for starting, as well as the normal position for running, also that this retarding device need only be available to a person operating the hand starter. The magneto is to be made with a hollow shaft, and provided with the adjustment for setting the timing through the shaft in the manner we have shewn. The H.T. connections to the distributor are to be radial, with central space to allow hand starter shaft to pass over. The conversion of the Watford machine to double spark would mean using two H.T. windings, and these might be placed with their axes vertical, one on each leg of the alternating portion of the magnetic circuit, suitable connections being provided front and rear for feeding the H.T. currents to the distributor, one of these connections being the usual running brush, and the other a fixed terminal carrying a short length of H.T. conductor connected to a brush in the centre of the distributor head. Provision for feeding a trailing brush on the distributor rotor for starting would have to be made by means of an eccentric brush in the distributor head, which would contact with (1) | ||