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).
Calculations for determining field winding resistance and equivalent wire gauge.
| Identifier | ExFiles\Box 64\1\ scan0122 | |
| Date | 30th April 1923 guessed | |
| -6- Ampere turns required = 300 Amperes = 108 ∴ No of turns. = 3 Length of mean turn 9½" approx. Therefore total length of field strip = 4 x 3 x 9½ + 9 say = 123" Estimated resistance for field winding = .0115 w at 20°C Whence ohms per 1000' at 20°C = 12000/123 x .0115 = 1.121 C.S. Area = .00815/1.121 = .00673 This is equivalent to round wire of gauge 13 S.W.G. _________________ [Watermark text: CLIFTON BOND] [Watermark text: MADE AT CROXLEY] / | ||