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).
Goshawk engine condenser capacity tests, observing misfiring speeds under different conditions.
| Identifier | ExFiles\Box 52\3\ Scan064 | |
| Date | 16th March 1922 | |
| EFC. {E. Fowler Clarke - Electrical Engineer} AB.41. V4430 16th March, 1922. X.4430 - COSHAWK CONDENSER CAPACITY. X.3485. X.2512. Some observations have been made, on the speeds at which misfiring occurs on a 5.0 mm. gap with various condensers of the LeC.1499 design (in paper) on the distributor. The coil used was S.P.1 with a secondary of 23,000 turns. Using condensers ranging from .25 mf. to .45 mf. the speed wbove which missing occurred, was from 1900 to 2000 r.p.m. of distributor, working on 12.3 volts. On 10.2 volts for the same capacity limits, the speed is just below 1500. No definite relation between the capacity and the "missing" speeds is apparent, but probably high speed working could be attained on 10 volts, by using a very small condenser, which is undesirable for other reasons. But for high speeds using 12 volts a comparatively large condenser is permissible. Hence it would appear necessary to consider very high speeds impracticable if for any reason, only 10 volts are available. In order to fix an upper capacity limit, as the capacity of paper condensers considerably increases with heating, a reliable test would be to fit a condenser of about .4 mf. to an engine, cover the casing with lagging and observe the operation of the ignition at high speeds. Meanwhile it would appear safe to allow an upper limit of .35 mf. for condensers intended for experimental chassis. FJA. | ||