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 graph showing the results of main-brush position tests on a Goshawk dynamo.
| Identifier | ExFiles\Box 50\5\ Scan172 | |
| Date | 11th January 1937 | |
| AMPERE OUTPUT DYNAMO RPM MAIN-BRUSH POSITION TESTS OF R GOSHAWKAero EngineCodename for 20HP Car / Aero Engine after KestrelAero Engine DYNAMO WITH 20 S.W.G FIELD Control brush adjusted in each case to give a final temperature, of from 70° to 78°C at maximum load. Final ambient temperature 19°C CURVE 4 Brushes - 4° retarded 70°C '' 3 '' - 3° '' 72°C '' 2 '' - 2° '' 72°C '' 1 '' - 1° '' 75°C '' N '' - in neutral position 70°C '' 1A '' - 1° advanced 72°C '' 2A '' - 2° '' 74°C '' D '' - *S Performance before end-plate slotting [Brushes about -0.5° retarded] Positions measured circumferentially on carcase from neutral position TEST | ||