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 motor design parameters, including armature dimensions, flux, and conductor numbers.
| Identifier | ExFiles\Box 35\4\ scan 035 | |
| Date | 1st July 1921 guessed | |
| -2- Contd. allow for torque losses, i.e. 72.7 lb-inches. Suppose we take a useful polar flux density of 6500 lines per cm.2, reckoned on minimum pole face. This is necessarily low to give a reasonable armature tooth density. Armature diameter = 2.850" Armature circumference corresponding to five slot pitches = 5/29 x π x 2.850". 5/29 = .1725 = 1.54" = 39 mm. Length - 2.50" - 63.5 mm. This gives a useful flux per pole of 6500 x 6.35 x 3.9 = 161,000. Number of conductors = (Tb x 10^8) / (1.41 P Ø C) = (72.7 x 2 x 10^8) / (1.41 x 4 x 161000 x 137) = 117. This agrees with 29 slots and coils, with two turns per coil, i.e. 116 conductors. Motor speed = 810. Contd. | ||