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).
List of advantages for a specific coil design, covering manufacturing, reliability, and performance.
| Identifier | Morton\M13.2\ img080 | |
| Date | 3rd August 1931 | |
| -3- HS{Lord Ernest Hives - Chair}/HEW2/ATL.3.8.31 contd. (a) Economy in manufacture using less of the more expensive secondary wire and owing to the H.T. being at the centre, a metal case which allows of better heat conductivity. Also simpler construction. (b) Deletion of ballast resistance. (c) Other makers say this coil has a bigger reliability than inside primary type. (d) Better flux interlinkage owing to windings being closer to the core with a laminated iron sheath round the outside of the windings. We appear to be the only people now using inside primary coils with the exception of Bosch who ingeniously use one of their ordinary magneto armatures fitted up in a metal case for use as an ignition coil. Owing to the almost exclusive use of this coil by other makers, there are probably other advantages of which we know nothing yet. HS{Lord Ernest Hives - Chair}/HEW. | ||