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 accuracy and maximum speed tests for car number 37-AU conducted at Brooklands.
| Identifier | ExFiles\Box 47\1\ Scan136 | |
| Date | 25th July 1925 | |
| S/W(Hto) X4117 BJ. c. to H.{Arthur M. Hanbury - Head Complaints} S/W. EF. S/W. Hs.{Lord Ernest Hives - Chair} CWBG/LHG.7.25. Please note re X page 2, & page 3 CAR NO. 37-AU - MRS. SOPER WHITBURN. I tested this car at Brooklands on Friday last to ascertain the maximum speed and to check the speedometer readings. One is only allowed to drive in one direction round the track, so that runs with and against the wind could not be made, but there is a measured mile each side of the track, and the figures given are the mean of those obtained on the two separate miles. In each case, under the particular conditions of Friday, the separate figures for each mile corresponded very closely. Five runs were made round the track, the first; keeping the speedometer reading steady at 40 m.p.h. and taking the time over the separate miles. the second; similar conditions, speedometer reading 50. the third; similar conditions, speedometer reading 60. the fourth; throttle full open, exhaust cut out, closed. the fifth; throttle full open - exhaust cut out, open. and the reading were as follow: Speedometer Reading. Time for one mile in seconds. Correspond-ing speed. Percentage errors. 40. 92 1/2 sec. 38.7 3.3 50. 75 48 4 60. 62.5 57.6 4 68 max. 56.6 63.6 70 max. 53.3. 67.67 | ||