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).
Calculation sheet comparing two wire gauges (18 S.W.G. and 19 S.W.G.) for a field winding.
| Identifier | ExFiles\Box 39\2\ Scan034 | |
| Date | 13th December 1932 guessed | |
| -5- Resistance of Mean Turn = volts per coil / A.T. per coil = 3.1 / 750 = .00413 ω Length of mean turn = 6 + .8π = 8.5" Ohms per 1,000 at 15°C. = 1200 / 8.5 x .00413 = 5.85 ___________________ 18 S.W.G. or 19 S.W.G. C.S. of Wdg Space = .65 x .75 = .487 Sq. area of wires = .00337 and .00250 Turns = 144 195 Length = 102' 138' Res. at 20°C = 1.83 ω 3.56 ω Current = 6.78 α 3.48 α A.T. = 977 673. ___________________ Therefore say 200 turns per pole for field winding. ___________________ Handwritten text: 46 yds .00775 ω per yd | ||