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).
Table of resistance and inductance particulars for various ignition coils at atmospheric temperature.
| Identifier | ExFiles\Box 69\1\ scan0183 | |
| Date | 8th February 1929 guessed | |
| X.4596 X.4079 x 4079 / 8710 PARTICULARS OF RESISTANCES AND INDUCTANCES OF R.R. GOSHAWK IGNITION COILS. at atmospheric temp't. PRIMARY Coil. | Resis. (W) | Imped. at 50 (W) | Reac. at 50 (W) | Induc. (hys) SECONDARY Resis. (W) | Imped. at 50 (W) | Reac. at 50 (W) | Induc. (hys) | Remarks. 4405 | .915 | 3.18 | 3.05 | .0096 | 4970 | 14000 | 13090 | 41.0 | Returned faulty from Cricklewood PWP1 | 2.30 | 5.48 | 4.97 | .0158 | 4740 | 14380 | 13570 | 43.0 | Waxed paper insulation on 7.P. windings. PWP2 | 2.25 | 5.48 | 4.99 | .0157 | 4860 | 14600 | 13770 | 43.2 | " | 7.P. BC25 | .92 | 3.24 | 3.11 | .0098 | 4721 | 13525 | 12680 | 39.8 | std 22 guage primary coils taken from production BC35 | .91 | 3.20 | 3.07 | .0096 | 4569 | 13360 | 12560 | 39.4 | " BC35X | .91 | 3.23 | 3.10 | .0097 | 4238 | 13100 | 12390 | 38.9 | " BC45X | .89 | 3.28 | 3.16 | .0099 | 4405 | 13185 | 12420 | 39.0 | " BC55X | .90 | 3.23 | 3.10 | .0097 | 4368 | 13125 | 12380 | 38.8 | " BC65X | .93 | 3.31 | 3.18 | .0100 | 4672 | 13270 | 12420 | 39.0 | " IS | 2.05 | 2.96 | 2.14 | .0067 | 3732 | 10035 | 9312 | 29.2 | Secondary wound next to core. Primary on the outside. LSI | .88 | 3.30 | 3.18 | .0099 | 4707 | 15200 | 14450 | 45.3 | Std 22 gauge primary coil with 20000 turn secondary. | ||