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).
Specification sheet for a standard tall stabalite encased battery ignition coil.
| Identifier | ExFiles\Box 54\5\ Scan257 | |
| Date | 29th April 1924 | |
| X3485 To R. {Sir Henry Royce} from EFC. {E. Fowler Clarke - Electrical Engineer} c. E. {Mr Elliott - Chief Engineer} & Ds. c. CJ. & PN. {Mr Northey} c. EY. EP. {G. Eric Platford - Chief Quality Engineer} GY. EFC {E. Fowler Clarke - Electrical Engineer} 3/T29.4.24. X.4596 - UP-TO-DATE STANDARD TALL RR. STABALITE ENCASED BATTERY IGNITION COIL. and X.3485 - UP-TO-DATE RR. BATTERY IGNITION GENERAL. The representative quantities of the new tall standard stabalite encased coil are as follows :- CORE. Length (inches) before turning over. 4.150" Dia. of wire (inches). .022" No. of wires. 740 approx. Total cross section of iron (inches 2). .282 sq." Saturation pole strength (at 10800 poles per sq.in). 3045 Saturation core flux. 38250 PRIMARY. Number of turns 300 ± 10 No. of layers. 4 Dia. of wire (inches). .028" Approx. resistance (ohms) (working condition). 1.18 Approx. inductance (secohms) (henries). .0096 BALLAST. Approx. resistance (ohms) (cold). .84 Approx. resistance (ohms). 1.35 (When carrying current of same heating value as working current at 8 volts at normal speed of timer and with primary gaps set as below under Contact Breaker). PRIMARY & BALLAST. Working total resistance (ohms) 2.53 Contd. | ||