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).
The interconnection of magneto and battery controls for airship engines.
| Identifier | ExFiles\Box 37\1\ scan 015 | |
| Date | 18th October 1917 | |
| To R.{Sir Henry Royce} from EH. Copy to BJ. " " E.{Mr Elliott - Chief Engineer} " " Ey. X.3199. EHL/LC18.10.17. 18th Oct. 1917. X.2038 Re - Inter-connection of Magneto & Battery Controls. X.3173. X.3191. X.3199. X.2020. On the Air-ship engines the control of the battery ignition and the magnetos are not interconnected. It was the Admiralty's wish that they should be separate. X.2814. On the Remy ignition on the air-ship engines they cut out the automatic advance which gave 10° range but have not increased the hand control to make up for this. They have had trouble because of having insufficient range. The range is 27° to 28°, very little more than the magneto. To obtain the full power with the Remy with this range it is necessary to get it to fire retarded the same position as the magneto 10° B.D.P. with this setting the engine gack fires when starting and is not nearly as good for slow running. We reckon we want at least 50° range on the battery so that it will fire 35° B.D.P. advanced and 15° A.D.P. retarded. With reference to the query at what speed we can start off the main magneto, when we were making tests with X.3161 the electrical starter on the Eagle we tried to see if we could start off the main magnetos, we found we could not do so, when the engine was cold we were running it at 28 to 30 r.p.m. with a hot engine we could occasionally get a start turning at 30 to 35 r.p.m. To be certain of starting under all conditions and allow for variation in magnetos we should estimate the engine should be turned at 40 to 45 r.p.m. EH. R.R. 55 A (770) V S.S. (B.S.D) 1M-9-4-17 G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1806 | ||