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 specifications for a sequence starter motor.
| Identifier | ExFiles\Box 64\2\ scan0160 | |
| Date | 16th June 1928 | |
| X.7625B. 16.6.28. SEQUENCE STARTER MOTOR. Motor torque 100 lb-inches = T. If C = amperes, then on characteristic of supply assumed E = 12 - .02C. and E.H.P. = 12C - .02C² watts. If efficiency = η then B.H.P. = η(12C - .02C²) watts. Hence, taking motor speed = N R.P.M. η(12C - .02C²) = α.TN(watts) when α = .01184 and .02C² - 12C + (α.T.N / η) = 0 Taking the running torque T the static torque (Ts) will be 10% greater, i.e. 1.1 T. Assume a useful polar flux density of B lines per cm² reckoned on the minimum pole face. Armature dia = D in inches. Armature circumference corresponding to 69% polar embrace 2.54 x (69/100) x π x D = 1.377 D cm. Armature length = L in inches. Then useful flux per pole Ø 1.377 D x 2.54 L x B = 3.50 BDL. Contd. | ||