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).
Analysis of aerodynamic improvements comparing open cars and streamline saloons, with proposals for new body designs.
| Identifier | ExFiles\Box 160\2\ scan0200 | |
| Date | 22th August 1934 | |
| -2- From the appendix it will be seen that the Streamline Saloon with the extra horse power of E.R. Hall's car would lap Brooklands at 104.5 M.P.H. as against the lap speed of 99.5 M.P.H. for his car. The value of 'K' for the open car is .00278 as against that for the Streamline Saloon of .001845, i.e. 51% higher. The greatest improvement to the open car was achieved by faring the front wings, giving 3 M.P.H. Subsequent modifications to the rear would have given greater benefit, had the front of the car not still have been very bad, and the maximum section not have been so far aft. Illustration 3 shows the chalk dust deposit on the ground, and from it may be seen how the front of the car causes the air to go wide of the body. Until this is cured by an improved frontal aspect no modifications to the rest of the car will produce any great result. Similar chalk records were made for the vertical section on a blackened plate and these showed a condition of turbulence occuring aft of the screen sections. From the streamline factor 'K' it will be seen that the open car has no semblance of an aerodynamic form, and that it is only better than the Standard Saloon or the Streamline Saloon for its drag due to its smaller projected area. For track work or a road race consisting of a number of straight stretches, it would appear that one can do equally well with a saloon as once can with an open car. Having done all we can with the body as fitted to E.R. Hall's car (B-35-AE), we propose to design a body complying with the Ulster Race requirements, giving it the best aerodynamic form we know of, and to test a model of it in the Wind Tunnel. We also propose to develop at the same time a design of 2-seater Saloon and an unrestricted open body. | ||