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 and considerations regarding polar flux density for Goshawk and E.A.C. motors.
| Identifier | ExFiles\Box 35\4\ scan 140 | |
| Date | 5th May 1923 guessed | |
| -2- Contd. A polar flux density (reckoned on the minimum pole face) of 6,000 to 7,500 lines per cm2 is about right. Taking 6,500 lines per cm2, Ø for the Goshawk motor is 161,000 lines, and for the E.A.C. motor is 194,000 lines, with the dimensions given. A polar flux density less than 6,000 lines per cm2 would require what would appear to be too small a number of ampere turns per pole on the field winding. If, now the motor speed is fixed, that fixes (within limits, by the simple rule) the relation of the number of conductors to the flux per pole. Owing to the high reduction ratio (32) chosen, the simple rule is not satisfied with the proposed number of conductors and suggested speed with either the proposed E.A.C. or Goshawk motor. In the case of the E.A.C. motor the quantities for instance are - Ø = 194,000 lines per ;ole as above. Z = 74 N = 1750 Ø,Z N= 2.53 x 10¹⁰ which is too big. Contd. | ||