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).
Critiquing the accuracy of performance tests on a Renault car published in motoring magazines.
| Identifier | ExFiles\Box 23\4\ Scan054 | |
| Date | 21th March 1925 | |
| R.R. 493A (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -3- Exptl. No. REF.Hs{Lord Ernest Hives - Chair}/RmL/LG21.3.25. car Renault can do over 85 m.p.h. with its 3.5 axle ratio. As will be seen from our figures, we estimate the maximum speed at 79 m.p.h. The general laxity of motor papers in quoting information is deplorable. In this weeks 'Autocar' the Renault is stated to develop 140 H.P. at 3000 r.p.m., in 'The Motor' tests 140 H.P. at 2400 r.p.m. The Autocar states that the Renault is turning over at 900 r.p.m. at 30 m.p.h; the car was fitted with a rev. counter. Using the tyre diameter and axle ratio we find that actually the engine should be doing 1025 r.p.m. at 30 m.p.h. so that the speedometer was reading 11% fast or very improbably, the rev. counter was slow. This is typical of these tests. The only method we know of getting even approximate comparisons between different cars is to use some independant instrument such as the 'Wimperis Accelerometer' which can be transferred from car to car. We cannot but think that the people who carried out these tests are not conversant with the fundamental principles of mechanics, or they would hesitate before publishing such figures. We have only thought it necessary to discuss briefly the way in which we have drawn our conclusions; should any question arise, we can let you have all the figures. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||