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).
Secret report on full-scale tests comparing the wind resistance of American and British cars.
| Identifier | ExFiles\Box 161\1\ scan0174 | |
| Date | 15th August 1938 | |
| Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} Hs.{Lord Ernest Hives - Chair} o.{Mr Oldham} to By.{R.W. Bailey - Chief Engineer} o.{Mr Oldham} to Da.{Bernard Day - Chassis Design} o.{Mr Oldham} to Mx.{John H Maddocks - Chief Proving Officer} o.{Mr Oldham} Da{Bernard Day - Chassis Design}/Sv. SECRET. 1380 Hm{Capt. W. Hallam - Head Repairs}6/H.15.8.38. WIND RESISTANCE OF AMERICAN CARS. We have been making some full scale tests of the American Cars that we have and also a 1938 Ford and comparing them with our own products. The method used is to measure accurately the H.P. at the road wheels by means of the experimental dynamometer and then get a timed lap speed for the car on the track. From this the H.P. required to lap at a given speed of 80 M.P.H. can be calculated with a possibility of error which is unlikely to exceed 2%. The results would be surprising if one did not remember that the Americans use the wind tunnel continuously when developing new designs, in fact we saw quite a dozen models last time we were at Chryslers. The basic facts are that a close-coupled Wraith, which has little if any more room in it than the Oldsmobile, requires 15% more road wheel horse-power (or 24%) to achieve a speed of 80 m.p.h., and Bentley III, which sells largely on performance, requires 27% more road wheel H.P. than the vee 8 Ford to lap at 80. We have inserted some tentative figures for the Paulin Bentley which we shall have to confirm when it comes over. It may be appreciably better than this estimate, but it indicates that, since the Ford is a four-door saloon with plenty of head room, its low wind resistance is a very excellent achievement. The Packard figures are rather illuminating, as this Company have stuck to their original radiator outline and, in consequence, though much better than the Wraith, are inferior in wind resistance to the Oldsmobile. | ||