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).
High-speed performance, discussing wind resistance, exhaust systems, and streamlining with a performance graph.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan42 | |
| Date | 12th June 1925 | |
| R.R. 433A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -5- Expl. No. REF: Hm{Capt. W. Hallam - Head Repairs}/Rm{William Robotham - Chief Engineer}2/LG121025. Graph: Y-axis: Road Wheel H.P. X-axis: Road Speed M.P.H. AB = Loss in Max. Speed due to Under-gearing (1.5 MPH) CD = Loss in Max. Speed due to Silencer (3.25 MPH) (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 [strikethrough] a maximum 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 maximum 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 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 streamlining. This was actually accomplished on The Thomas Special car this year. contd :- | ||