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 log sheet for various 48 coil medium output dynamo machines.
| Identifier | ExFiles\Box 62\3\ scan0160 | |
| Date | 23th January 1931 | |
| X6004 /50 N.B. MACHINES. PERFORMANCE COMPARISON OF DYNAMOS. 48 Coil Medium Output Machines (on routine procedure of 1.4.27) Date | Dynamo. | Particulars and remarks. | (1) | (2) Brush angles. | | (3) Temperatures. | | | Peak | | | | | Main. | Control | Amb. | Rise. | Machine. | Amps. | Speed. 5-1-31 | XI.1S.SS.{S. Smith}X | First machine arranged with 65c' setting and fitted to Sg{Arthur F. Sidgreaves - MD}'s car. | OK | 16° | 128.5° | 13 | 64 | 77 | 15.4 | 1,680 15-1-31 | Y.5S.M | From Production. | O.K. | 15° | 128.5° | 17 | 63.5 | 80.5 | 16.4 | 1,630 19-1-31 | Y.6S.M | " " | O.K. | — | 129° | 15.5 | 57.5 | 73 | 14.7 | 1,620 20-1-31 | Y.7S.M | " " | O.K. | — | 127.5° | 18.5 | 59.5 | 78 | 14.3 | 1,550 21-1-31 | Y.8S.M | " " | O.K. | — | 128° | 15.5 | 65.5 | 81 | 14.6 | 1,690 23-1-31 | Y.9S.M | " " | O.K. | — | 128° | — | — | — | — | — | ||