Wind tunnel testing and drag coefficient correlation for a streamlined Bentley car.
| Identifier | ExFiles\Box 161\1\ scan0042 | |
| Date | 29th October 1937 | |
| Hs. {Lord Ernest Hives - Chair} from Rm. {William Robotham - Chief Engineer} c. Hy. {Tom Haldenby - Plant Engineer} W/P {Derby Works / Production} - Sr. Ev. {Ivan Evernden - coachwork} Rm {William Robotham - Chief Engineer} 3/R.29.10.37. STREAMLINEExperimental Streamline Bentley B.23.A.ED CAR - BENTLEY. During the previous tests which we carried out on Bentley cars having bodies fitted with reduced wind resistance we evolved a correction factor which enabled us to accurately determine the maximum speed of any particular car from the drag figures estimated in the wind tunnel. Even when the reflection method of measuring drag was used in the wind tunnel, which invariably gives the highest drag co-efficient and is considered to be the most accurate experimental method, we found that the drag figures obtained had to be increased by about 10% to correspond with the results obtained on the finished car. That we can accurately predict the speed of the car is indicated in Hs {Lord Ernest Hives - Chair} 2/MJ. 7.11.33.attached. In view, therefore, of the expenditure which will be incurred by sending a car over to France and having a body built, we are proposing for the model left by Sr. to be tested in the Vickers wind tunnel against our streamlineExperimental Streamline Bentley B.23.A.Ed model. We should then be able to ascertain immediately what we are likely to get out of the experiment. Incidentally, if anything like the anticipated speeds are realised there is only one way of satisfactorily gearing the car to take advantage of the body, and that is to fit an overdrive gearbox. We have arranged to have one day in the Vickers wind tunnel early next week. Rm. {William Robotham - Chief Engineer} | ||
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).