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).
Comparison table of different magneto models detailing their lowest operational speeds and performance remarks.
| Identifier | ExFiles\Box 4\5\ 05-page241 | |
| Date | 31th January 1918 | |
| -2D Contd. Magneto. | Type and number. | X. No. | Lowest speeds. | Remarks. ---|---|---|---|--- | | | Adv. | Comb. | Retd. | R.{Sir Henry Royce} Bosch. | Z.R.6. 2571556. | 427. | 260 | 170 | 246. | Advanced position same as maker's. Retarded position 2.5º earlier than maker's. U.S.A. Bosch. | Z.R.6. 2998784. | 3916. | 120 | 162 | 240. | Advanced position same as maker's. Retarded position 3.5º earlier than maker's. Dixie. | Aero 648. 718237. | 3724. | 180 | 180 | 185. | Sparking speed unaltered by advancing or retarding, hence figures as first obtained on maker's range are representative. Conner. | C.M.1 | 4210. | 350. | 260. | 170. | Retarded position same as makers, this position giving minimum regular sparking speed. Further retard again increased speed rapidly. Advanced position 14.5º later than maker's. | | | (Weighted averages of two sets of figures) | | | B.T.H. | F.M.6. R.311941. | 3515. | 244 | 192 | 220. | Advanced position 10º earlier than maker's. Further advance limited by fouling of timing lever, but apparently would further reduce the minimum sparking speed in retarded position. Retarded position 21.5º earlier than maker's. Footer: AERO-ENGINES MISC NO 56(1000) P.O.S. 31/1/18 | ||