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).
Speedometer scale calibration report showing drive shaft RPM vs indicated and correct MPH, with percentage error.
| Identifier | ExFiles\Box 59\2\ Scan291 | |
| Date | 15th December 1933 guessed | |
| Speedometer. G.847. Scale Calibration :- Revolutions per minute of drive shaft. M.P.H. reading bn{W.O. Bentley / Mr Barrington} dial Correct M.P.H. when driven at R Revs. per mile. Percentage error Fast. Slow. 133 10 9.85 1.5% 260 20 19.3 3.5% 390 30 29.0 3.3% 524 40 38.8 3.0% 648 50 48.0 4.0% 773 60 57.4 4.3% 930 70 67.8 5.1% 1030 80 75.6 5.5% 90 100 Remarks :- | ||