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).
Performance comparison of dynamos on single modification 20 HP machines.
| Identifier | ExFiles\Box 165\6\ img155 | |
| Date | 1st April 1927 | |
| X.5660 PERFORMANCE COMPARISON OF DYNAMOS. (on routine procedure of 1.4.27). SINGLE MODIFICATION 20 HP. MACHINES. Date. D/No. Particulars and remarks. (1) Brush angles. min. control (2) Brush angles. max. (3) Temperatures. Amb. Machine. Peak Amps. Speed. 17.2.27 P2KM Opt from Test Dept 16/40ss{S. Smith} off CB atard. 1° OK 12° 126° - - - 4.3.27 P6KM " 2° OK 12° 127° - - - 1.4.27 I2RM{William Robotham - Chief Engineer} " 0° OK 13.5° 122.5° 17°-49°-66° 11.1 2030 23-6-27 L70M " 1/2° OK 12.5° 122.5° 20-56°-76° 11.4 2000 H 4.27. | ||