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).
General specification of performance for a 12-cylinder, four spark per revolution magneto for the Falcon X aero engine.
| Identifier | ExFiles\Box 43\4\ Scan035 | |
| Date | 13th December 1926 | |
| X4021 13.12.26. GENERAL SPECIFICATION OF PERFORMANCE OF 12-CYLINDER FOUR SPARK PER REVOLUTION MAGNETO FOR RR. FALCON X. AERO ENGINE. X38328 X4021 (1) The weight of the magneto complete but without screening cover and coupling shall not exceed 16 lbs. with metal screen, 17 lbs. (2) The length of the H.T. safety gap shall not be less than the equivalent of a sparking over voltage of 12000 steadily applied. This, in ordinary forms of safety gaps will correspond to certainly not less than 8.5 mm. and probably somewhat more. (3) The total firing range in magneto degrees shall be 15°±1°. (4) The magneto shall be capable of complying with the performance scheduled in (5), (6) and (7) below, after first having been subjected to :- (a) A short endurance test in which the magneto shall be run for 7 hours at a speed of 2000 r.p.m. with timing lever fully advanced and sparking being caused to take place on a sequence of H.T. third point spark gaps in air set to 5.5 mm. (b) Immediately following (a), a short circuit test in which it is run at 1500 r.p.m. for a quarter of an hour with timing lever central and primary and secondary windings short circuited, i.e. with the low tension and central high tension distributor terminals connected to the metal framework of the magneto. (c) Immediately following (b) an open circuit test at 1500 r.p.m. for one minute with timing lever fully advanced and the H.T. terminals not connected to anything, so that the secondary discharges take place on the safety gap of the magneto. Contd. | ||