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 table for various dynamos based on routine procedures.
| Identifier | ExFiles\Box 60\1\ Scan199 | |
| Date | 1st April 1927 | |
| -2- 40/50 L.B. MACHINES. PERFORMANCE COMPARISON OF DYNAMOS. (On routine procedure of 1.4.27) Dynamo. (4) Speed for 10V. 14V. 17V. (5) Speed for 0 amperes. Peak Speed. Amperes. 2500 RPM. amperes. (6) Speed for 10V. 13.6V. 17V. (7) Speed for amperes. 0. 8 15. H.O.1. 805 805 1760 15.6 13.35 2. NB.HO 835 835 1740 14.9 13.2 3. NB.HO 870 870 1900 15.0 13.4 4. NB.HO 815 815 1700 16.4 14.3 18. HO. SS.{S. Smith} * 860 850 860 850 PII Type. 1910 14.9 1815 15.4 13.0 10.8 at 3,400 | ||