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).
Page of calculations for an armature and field winding.
| Identifier | WestWitteringFiles\K\June1923\ Scan77 | |
| Date | 19th June 1923 guessed | |
| -5- Contd. Armature diameter at root of tooth = 3.100 - .875 = 2.225 Circumference ditto = 7.00" For one tooth and slot =.171 Hence width of tooth at root = .071 (Here see table p.6) Ampere turns per pole required = 728 Amperes = 178 Turns per pole required = 4.1 i.e. say 4½ since half a turn is desirable from the point of view of getting in the connections. Approx. length of mean turn = 9¼" Total length of field strip = 4 x 4½ x 9¼ + 7" (say) = 173" Estimated resistance of field winding = .010 w at 20°C Resistance of strip per 1000' at 20°C = 12000/173 x .010 = .695 w. Contd. | ||