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).
Windage tests conducted on a Bentley II car using deceleration methods.
| Identifier | ExFiles\Box 161\1\ scan0247 | |
| Date | 1st November 1938 | |
| -3- BENTLEY II (6.B.IV) WINDAGE BY DECELERATION METHODS. The following results and deductions are the outcome of deceleration tests carried out on the Bentley II, 6.B.IV. Flat, straight concrete road, 1½ miles long with fast approach curves at either end was used for the test, deceleration being measured accurately by means of the chronograph in conjunction with a contact on the O/s rear wheel. These tests were carried out (1) with the car in normal condition, and (2) loaded to an approx. addition of ½ ton, the original idea being to derive K direct from the two curves thus obtained, and hence find values for rolling resistance by substituting back in one of them. Despite the fact that a curve was obtained under ideal conditions, i.e. no difference in curves obtained in either direction, this method depending as it does on reading off the difference between the differential curves of deceleration, was found to be insufficiently accurate to indicate possible small variations in K especially at high speeds. The more accurate differential curve - that obtained in the loaded condition - was therefore taken and used to derive K from the Andreau formula. K = W / (2255V1V2 A) * { (101.7 (V1 - V2) / t) - RT } Rm{William Robotham - Chief Engineer} being the value obtained from the Andreau formula for rolling resistance. Cont'd.{John DeLooze - Company Secretary} | ||