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).
Test report and analysis of a Lucas motor's performance specifications and brake test results with a Goshawk engine.
| Identifier | ExFiles\Box 51\5\ Scan075 | |
| Date | 1st January 1922 | |
| Contd. -2- EFCl/T3.1.22. Air gap .015" = .38 mm. No. of wound poles 4 Arrgt.of field coils. All in series. Resistance of field circuit. .0088 ohm. at 18°C No. of armature slots 29 No. of commutator bars 29 Armature resistance .0098 ohm at 18°C Commutator diameter 1.375" useful length .700" Brush contact area 2 x .50" x .30" = .300 sq.in. Ratio of field resistance to armature resistance. .898 Length of armature overhang - at driving end. .650" Length of commutator connections (excluding spokes) .700" Ditto (including spokes) - .850" The motor behaved very well on the bench brake test. Attached are blueprints of the curves obtained with a volt-ampere characteristic of supply to the motor to our standard amount of 1 volt drop from 12 volts per 50 amperes. With the Goshawk engine cold, requiring according to our estimation, a motor torque of 66 lb-inches, the motor speed would, with these results, be 750 r.p.m., and the engine speed 89 r.p.m. The other quantities at this point would be as follows :- Amperes 187.5 Volts 8.25 B.H.P. .80 Efficiency. .38 It will be seen that this Lucas motor would be working at a higher torque than that corresponding to its maximum power, and therefore it does not seem that the motor as wound is best suited to the 8.4 ratio. If the ratio were, | ||