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).
Page discussing high-speed performance, covering windage, exhausts, and streamlining, with an accompanying performance graph.
| Identifier | ExFiles\Box 178\1\ img011 | |
| Date | 12th October 1925 | |
| - 9 - REF. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG121025. Graph Labels: Vertical Axis: ROAD WHEEL H.P Horizontal Axis: ROAD SPEED M.P.H. A B = Loss in max. speed due to under-gearing (1.5 m.p.h.) C D = Loss in max. speed due to silencer. (2.25 m.p.h.) (4) HIGH SPEED PERFORMANCE. Windage. With a normal touring car, a large increase in engine power will only produce a very small increase in max. speed due to the rapid increase in wind resistance. A good example of this is the New PhantomCodename for PHANTOM I and Silver Ghost cars. The former has 33% more power but a max. speed less than 10% greater than the latter. Exhausts. In the same way, a free exhaust (cutout), though it effects an appreciable gain in horse power, increases the max. speed but little. The main function of a cutout is to improve the high speed acceleration which it undoubtedly does. Projected car area. Streamlining. It should be remembered in considering a sporting car body that figures for the projected windage area of the car do not mean very much. It is possible to reduce the wind resistance of a given projected area 50% by careful (contd). | ||