Calculations and specifications for a Japan Sequence Starter Motor.
| Identifier | ExFiles\Box 62\1\ scan0100 | |
| Date | 9th December 1932 | |
| X6091 9.12.32. JAPAN(Experimental Engine) SEQUENCE STARTER MOTOR. Engine torque when turning cold (0°C.) estimated at 600 lb.inches. Engine speed at this torque estimated at 68 R.P.M. approx. Gear ratio 12.7 : 1.00 Motor speed = 880 R.P.M. Assuming an overall mechanical efficiency of 76.5% the required motor torque will be 60 lb. ins. The motor power is therefore :- .01184 x 60 x 880 = 668 watts. Assuming an electrical efficiency of .40, under the above conditions, the applied power would be 1670 watts or 220 amperes at 7.60 volts. Assume a useful flux density reckoned at the pole face of 6500 lines per sq.cm. Armature diameter = 2.800" (average) Armature circumference corresponding to 70% Polar arc = (70/400) x 3.142 x 2.800 = 1.54" or 3.91 cm. Armature length 3.000" or 7.62 cm. Flux per pole = 3.91 x 7.62 x 6500 = 194 x 10³ lines Number of armature conductors required therefore :- = (Tb x 10⁸) / (1.41 x P x ΦC) = (60 x 2 x 10⁸) / (1.41 x 4 x 194 x 10³ x 220) = 50 Suggest trying a 29 slot armature with 29 coils, one turn per coil. ----------------- | ||
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).