The accuracy of an A.C. revolution counter and speedometer, with recorded water temperatures during a road test.
| Identifier | ExFiles\Box 83\2\ scan0125 | |
| Date | 8th November 1937 | |
| -2- Rm {William Robotham - Chief Engineer} /IMW. {Ivan M. Waller - Head of Chateauroux} 11/MH. {M. Huckerby} 8.11.37. It will be noted that the A.C. revolution counter underestimates the engine speed by approximately 1.7% and that the A.C. speedometer is to all intents and purposes accurate. Water temperatures were also taken on the road. With the air at 12°C the mean of ten readings in 140 miles was - Rear of block 78.7°C. Top water pipe 77.6°C. The maximum running temperatures were 80°C and the minimum 76°C on both thermometers. After five minutes idling at a level crossing the water temperature rose to 95°C. Rm {William Robotham - Chief Engineer} /IMW. {Ivan M. Waller - Head of Chateauroux} | ||
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).