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).
Results and comparison of wind tunnel tests on a Bentley saloon car.
| Identifier | ExFiles\Box 160\2\ scan0161 | |
| Date | 4th December 1933 | |
| X+Y781. To Wox. from EV.{Ivan Evernden - coachwork} C. Eg. S. C. Gr.{George Ratcliffe} Hs.{Lord Ernest Hives - Chair} C. __. Da.{Bernard Day - Chassis Design} C. Ph. Bn.{W.O. Bentley / Mr Barrington} EV.{Ivan Evernden - coachwork}1/KT.4.12.33: WIND TUNNEL TESTS - BENTLEY. We have already reported on tests No.1 to 21 in our EV.{Ivan Evernden - coachwork}14/KT.27.6.33. All of those tests were on the standard Saloon Body with modifications to the wings, screen, and tail. They were carried out by the "Flat Plate Method". The attached data sheet includes all the figures for the first experiments, and those for the second series. A comparison was made to discover the effect of the three accepted methods of testing. (1) Model suspended in space. (2) Flat plate slightly inclined as a ground. (3) The Reflex method. From the attached table it will be seen that the "Flat Plate" method gives a drag approx. 85% of the Reflex method. In view of this, all the drags of the first series of tests have been increased proportionately. If one takes the tunnel drag and calculates the drag of the full size car at any given speed, this drag will be anything from 20% to 38% too low. From the appendix attached it will be seen that the drag due to windage can be computed for any known car, given the horsepower and the speed. This we have got for the standard saloon Test No.3. of the first series, and for the streamlined saloon Test No.28. All the full size drags have been computed proportionately from these two known actual drags, in the ratio of the Tunnel drags. From these car drags we have computed the actual "K" for each car, and the maximum lap speed. The estimated half mile and maximum road speeds are taken pro rata with the standard saloon and the streamlined car. | ||