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 impact of streamlining, gear ratios, and braking systems on vehicle performance.
| Identifier | ExFiles\Box 160\2\ scan0060 | |
| Date | 12th October 1925 | |
| R.R. 493A (50 H) (D.D. 31. 12-6-25) J.H.D. EXPERIMENTAL REPORT -10- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/L/121025 realised that the outline of a car beneath the frame is of great importance with regard to wind resistance, a cushion of air tries to form between the car and the road, which can be eliminated by streamlining. Gear ratio: Owing to the high wind resistance of the bodies they carry, normal cars (touring) are not geared for max. speed but rather, lower. They are therefore rather over the peak of the power curve when all out on the road and lose perhaps 5% in H.P. This loss in H.P. can hardly be detected. The gain in acceleration, however, is appreciable. When the windage of the car is reduced considerably, 5 HP. can make an appreciable difference in speed. A sports car may therefore benefit by a high axle ratio, where a touring car would lose in acceleration, while the increase in maximum speed would not be detected. (5) BRAKING. Fundamental laws. Weight of car. Gradients. Distance, and time to rest. Windage. Rotating parts, and pedal pressure. Max. rate of retardation. Personal comfort. Fundamental laws. (road surface): The rate at which a car can stop is not under the control of the designer. When the braking system has been arranged to give smooth and pro-gressive action and to lock all four wheels (if required) with a reasonably light pedal pressure, the engineer has done every-thing possible, external conditions dictate the way in which contd :- | ||