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 armature resistance, dimensions, and slot area.
| Identifier | ExFiles\Box 64\1\ scan0148 | |
| Date | 19th June 1923 guessed | |
| -4- Contd. Resistance of one armature turn = .007 x 4 / 41 = .000683 Length of armature turn = 11" approx. Resistance per 1000' = 12000 / 11 x .000683 = .746 W But ohms per 1000' at 20°C = .00815 ÷ cross sectional area (a) Whence a = .00815 / .746 = .0109 sq.ins. Take a copper space efficiency of 50% Then slot area = 4 x .0109 = .0436 sq.inches. Total area of all slots = 1.79 sq.inches. Suggested slot depth not to exceed (√ 1.79 / 2π) = √.285 = .534 Corresponding width . = .0816" Suggested slot depth and width = .4375 deep by .100 wide. Contd. | ||