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).
Letter discussing wind tunnel figures and correction factors for a T.T. model car.
| Identifier | ExFiles\Box 90a\4\ Scan011 | |
| Date | 13th January 1936 | |
| x762 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}5/KW. 13th January, 1936. Mrs. E.R. Hall, 53, Berkeley Court, London, N.W.1. Dear Mrs. Hall, Thank you for your letter of January 9th. I was most interested to see your wind tunnel figures. I do not know whether Vickers are using the same method as previously in taking the drag figures but from the results I do not think they are. Whether they are or not, I think it is absolutely imperative that you should get a check figure while these tests are in progress on an exact replica of the car as it ran in last year's T.T. If you get this figure you will know what increase in speed to expect approximately with a new body, because you know the lap speed at Brooklands of last year's T.T. car. I expect you will find when you put last year's T.T. model in the wind tunnel that it should have lapped Brooklands at 110 M.P.H. This means that the correction factor for the wind tunnel on these particular models is somewhere about 10% in speed. When you have got all the figures I think it might be useful if I came down to Vickers and discussed them with the wind tunnel operator and yourselves, to see we get a common basis. Please get one of the models converted back to last year's T.T. and get this figure, because without it I think the others lose most of their value and we shall all be very disappointed in the results unless we get the right correction factor. | ||