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).
Technical memorandum discussing torque effects, tyre losses, and the results of various tyre tests.
| Identifier | ExFiles\Box 158\2\ scan0042 | |
| Date | 9th June 1939 | |
| -4- should come to overdrive losses. This torque effect should not prevent the application of figures already obtained to full throttle maximum speed running. In estimating the tyre loss at part throttle speeds however, it would probably be more accurate to use the figures shewn in the previous memo. which were obtained with the dynamometer declutched for use as front wheel losses. Changing the rear tyres from new Dunlop at 28 lb.in.2. to new India at 40 lb/in.2. should make 7% improvement to acceleration at 50 m.p.h. in direct gear. (5) The effect of rear axle loading on tyre loss. Curve sheet 12. These curves were taken in direct gear for the sake of accuracy of readings and suffer from a torque effect in consequence. Only at the higher speeds (85 m.p.h.) do the top two curves begin to give losses proportional to loading and even there the lightest loading curve is a long way out. (6) The effect on curves obtained of the time allowed for warming up. This test was carried out with 6.50 x 19 Dunlop Track Racing tyres. The tyres were warmed up for 15 minutes at 60 m.p.h. full throttle and a curve was then taken. They were then run for a further 10 minutes at the same speed and another curve was taken. This was repeated again and then a further curve was obtained immediately after stopping for 40 minutes. On the following day a curve was taken after warming up for 15 minutes at 60 m.p.h. as in the first instance. No definite change in loss over the whole range was noted under any of the above conditions. In other words a curve obtained after warming up for 15 minutes is as good as any. This may be due to the extremely rapid warming up which is experienced on the drums at 100 m.p.h. The tyre pressure certainly never changes if the tyres are kept running when once they have been run up to this speed. Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} | ||