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).
Analysis of a Brooklands test on the Sports Phantom, discussing methods to increase maximum speed through gearing changes and weight reduction.
| Identifier | ExFiles\Box 70\1\ scan0111 | |
| Date | 8th September 1927 | |
| to Hs{Lord Ernest Hives - Chair} from Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} X8774 EV{Ivan Evernden - coachwork}3/8.9.27. copy to E.{Mr Elliott - Chief Engineer} W. H.{Arthur M. Hanbury - Head Complaints} RE 10.EX. On analysing the report of the test on Brooklands of the Sports Phantom we have come to the conclusion that such changes as, removing the wings and tail, hood up or down, etc., make a relatively small difference to the maximum speed because one is operating at the peak of the engine power curve. A decrease in head resistance does not result in a proportional increase in speed. If we wish to obtain a higher maximum speed, we can do so by either (1) moving the power curve peak to a point of higher engine revs. (2) reducing the weight of the car, so that we can use a 17 tooth pinion and get the same accelerations as have been obtained with a 16 tooth pinion. We believe that suggestion (2) is well within the bounds of possibility, as the total weight of 10 EX. is excessive even for an ordinary open car. The complete car with one spare wheel weighs 5200 lbs. (2ton.6cwt.1qr.20lbs.) which gives a coachwork weight of 11.750 cwts. Everything points to the desirability of using a 17 tooth axle, save on account of acceleration. We believe that this objection could be overcome by reduced weight in the coachwork. The calculations, attached herewith, indicate that a reduction of 324 lbs in the weight of 10.EX as run on Brooklands would enable the higher gear axle to be used without any loss in acceleration. We consider that we shall have to make a sports body weighing at the most 7cwts if our Sports car is to be any good. The efforts of established coachbuilders with their heavy and unscientific constructional methods cannot succeed in this. 5.3 | ||