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 making and testing of an experimental Goshawk battery ignition coil.
| Identifier | ExFiles\Box 45\4\ Scan097 | |
| Date | 21th November 1922 | |
| R.R. 159 (2500) (SD629 19-7-17) MP18/656 X4079 c.c. To R & E.{Mr Elliott - Chief Engineer} from EFC. c. CJ. & PN.{Mr Northey} c. By.{R.W. Bailey - Chief Engineer} & EP.{G. Eric Platford - Chief Quality Engineer} c. Rg.{Mr Rowledge} & Da.{Bernard Day - Chassis Design} EFC1/T21.11.22. X.4079 - GOSHAWK BATTERY IGNITION COIL. (1) We have in hand the making of an experimental coil with:- (a) Larger cross section of core (30% increase) (b) Longer core. (3/8" longer). (c) Deletion of hedgehogging. (d) Four-layer primary with improved insulation, (280 turns) (e) 18,000 secondary turns disposed with plenty of end insulation and with three layers of .00075" oiled paper between each layer. (f) Coil case of mouldensite, allowing air space all round the secondary. (2) The central high tension wire with the ignition coil in operation under average conditions conveys a current in one direction of about 2 1/2 milli-amperes. This naturally only represents the unidirectional portion of the discharge. The A.C. value of this same current measured on the dynamometer type instrument reads about 8 1/2 milli-amperes. This must not, however, be taken as quite correct because the instrument is not suited to the high frequencies contained in this ignition current. (3) We have endeavoured to measure a leakage current from a coil surrounded by a tin-foil wrapping, when the coil is in the condition that earthing the wrapping will stop the engine firing. On the D.C. instrument we find this to be less than 1/10 milli-ampere, in fact we can only just see the indication at all on the instrument when the engine is stopped by the leakage passing through it. On the A.C. instrument the scale is rather close at the bottom, but the | ||