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).
The effects of wind resistance and hill climbing on car performance.
| Identifier | ExFiles\Box 39\2\ Scan211 | |
| Date | 12th June 1925 | |
| R.R. 493a (50 H) (D.D. 3), 12-6-25 J.H.D. -6- Expl. No. REF Hs{Lord Ernest Hives - Chair}/Rn{Mr Robinson}2/LG121025 EXPERIMENTAL REPORT. Wind resistance. As this increases as the square of the speed, it is obvious that it is of primary importance at high speeds. In judging a normal car performance we should say that if a criticism is to be made of its performance at speeds above 50 m.p.h., direct information of the wings and body should be obtained. The whole subject of streamlining is rather involved. A saloon body frequently has less windage than a touring body with the hood up. It is absurd to attempt to obtain high speeds with large front wings as fitted to R-R cars; we estimate that without alteration to the axle ratio the removal of these will put 6 to 7 m.p.h. on the speed of the car. The type of mud-wing fitted to the new 3-litre Sunbeam shews their appreciation of this point. We consider any information on the high speed performance of a car taken without a calibrated speedometer is useless unless the tests are timed on a track. (3) HILL CLIMBING. Connection with acceleration. If it were not for carburation troubles, the accelerating capacity of a car could be directly deduced from its hill climbing performance; as it is, however, most cars will function better when a steady power output is required from them as in hill climbing, than when full power and increasing engine speed is required from them as in acceleration. For practical purposes however, hill climbing performance is a very good guide to acceleration capabilities. In every case when a car is said to be able to climb a hill of a certain gradient, the car must be able to hold a given speed indefinitely on the hill; rushing a hill gives no information. | ||