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).
Tests to determine if a speedometer shows lag during vehicle acceleration.
| Identifier | ExFiles\Box 113\2\ scan0024 | |
| Date | 15th January 1923 | |
| X1725 15.1.23. TEATS CARRIED OUT (11.12.22) TO DETERMINE WHETHER SPEEDOMETER SHOWS ANY LAG IN FOLLOWING UP SPEED OR NOT. X1725 ~~X613~~ The object of these tests was to discover if accelerations, as determined from the speedometer, were sufficiently accurate for ordinary purposes. This was accomplished by passing a point at a fixed speed, accelerating, and taking time to a second point whose distance from the first was known. The first attempt made was on top gear and failed because the increment of time was too small in comparison with the resulting acceleration. Also, the timing was only done with one stop watch. The second attempt was made on 3rd. speed, the mean time being taken by two stop watches. The following results were obtained from six tests on 3rd. speed and six tests on 2nd. speed. Only those of the 6 that appear to be reasonably accurate, are appended. From these it will be seen that the lag, if any, is too slight to have any material effect upon accelerations taken by speedometer in the ordinary way up to 4 f.p.s^2. The errors on 2nd. speed are probably as much due to inaccurate timing (1/5 sec. makes a considerable difference) as to the speedometer. An Elliott speedometer was used for these tests. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||