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).
Comparing car performance data from published tests with calculated figures and independent measurements.
| Identifier | ExFiles\Box 73\3\ scan0292 | |
| Date | 21th March 1925 | |
| R.R. 493A (50H) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -3- Expl. No. REF. Hs{Lord Ernest Hives - Chair}/Rnl/LG21.3.25. (from the illustrations and Reg.No., is the same car as was used for 'The Motor' tests), is stated to develop 140 h.p. at 3000 r.p.m. and The Motor states 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 11½% fast or very imporbably, the rev. counter was slow. This is typical of these tests. The only method we know of even approximate comparisons between different cars is to use some independent instrument such as the 'Wimperis Accelerometer' which can be transferred from car to car. 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}/Rn{Mr Robinson} | ||