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).
Page detailing the methodology for calculating air drag from dynamometer horsepower figures and test results.
| Identifier | ExFiles\Box 161\1\ scan0219 | |
| Date | 10th September 1938 guessed | |
| -2- It would be inadvisable, however, to judge from one isolated case. In calculating these values of K it has been assumed that dynamometer horse power figures given for the various speeds have been those available after subtracting the rolling resistance for the rear axle weight, i.e. for each particular speed and horse power the corresponding tractive effort is calculated and from this the rolling resistance of the front wheels only is subtracted to obtain the air drag figure. For the three throttle stop positions of 28-G-VI. the lap speeds given were 50, 65 and 73 m.p.h. and the corresponding dynamometer horse powers were 26.2, 42.6, and 59.2. Increase of weight from 41 1/2 to 51 1/4 cwt reduced lap speed from 73 to 71.4 m.p.h. Da{Bernard Day - Chassis Design}/DB.{Donald Bastow - Suspensions} | ||