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).
The performance testing of the Paulins Streamline Bentley car, comparing actual track results with wind tunnel predictions.
| Identifier | ExFiles\Box 161\1\ scan0116 | |
| Date | 15th July 1938 | |
| 1380 SECRET. Sg.{Arthur F. Sidgreaves - MD} From Rm.{William Robotham - Chief Engineer} Dr. Ds. Ds/EV.{Ivan Evernden - coachwork} Dr.Jar. Dr. - Sr. RmS/R.15.7.38. PAULINS STREAMLINE BENTLEY CAR. The speeds which we expected to get from this car after calculations from figures obtained in the wind tunnel were given in DA{Bernard Day - Chassis Design}/EV{Ivan Evernden - coachwork}17/M.10.11.37., the car was taken to Montlhery on Tuesday and Wednesday last week by Sr. and RM.{William Robotham - Chief Engineer} The weight of the car, without bumper bars, was less than 38 cwts. Considerable weight savings have, of course, been effected by generous use of Duralumin. For some unexplained reason the cost of the body was reasonable. The car lapped @ 103 m.p.h. The standard Paris saloon lapped @ 90 m.p.h. We carried out some tractive resistance tests to separate the wind resistance of the car from the horse-power, and our conclusions show that, although the wind resistance was not as good as anticipated from the wind tunnel tests, it should have given an appreciably higher lap speed than actually recorded. We attribute some loss in speed to:- (1) The fact that the car was slightly over-geared for the track as 4,100 revs. were never exceeded. (2) The engine being a new production unit was not quite free for continuous high speed work. It will be extremely interesting to repeat the tests with smaller road wheels when the car has covered a considerable mileage on the road. In view of the somewhat optimistic predictions as a result of the wind tunnel tests, a speed of 103 m.p.h. may, at first sight, seem disappointing. However, since the horse-power required to propel a car at high speed varies | ||