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).
Appendix detailing notes on tyre loss results and further areas for investigation.
| Identifier | ExFiles\Box 158\2\ scan0043 | |
| Date | 9th June 1939 | |
| -5- RM{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}5/JH.9.6.39. Appendix - Notes on tyre loss results so far obtained. A glance through the preceeding report reveals that as more results are obtained, so further fields for investigation are opened up. This is particularly so with regard to the full throttle losses in each gear. Here it would be interesting to know whether it is the tread pattern or the internal construction of the Dunlop tyre which is making it perform differently to the India tyre. To discover an answer to this, tyres would have to be used having had their treaded portion removed before use, since there is no certainty that the loss due to the internal construction of a tyre remains constant throughout its life. The effect of rear axle loading might perhaps better be investigated with the dyno. declutched and no torque on the tyres. Some satisfactory answer has yet to be given for the extremely low loss shown with the 6.50 x 16 trackracing tyres. Apparently there is no end to the number of variations which may be played on the theme of a chassis dynamometer. It remains to be seen how many of these have a real bearing on the performance of a motor car on the road. In other words, the torque effect shewn on the drums is presumably due to tyre deformation, and that deformation may be a very different thing on a flat road surface vibrating relative to the wheel. If the direct reading accelerometer which is at present being made by the Electrial Department is a success then such effects can be investigated on the road and dyno. figures which at present should not be applied too literally to the road can be given a real road value. Power losses in tyres. Appendix 2. Verification of losses in direct gear by recording the effect of changing rear tyres. The acceleration times given below were each observed to be exactly the same three times in each direction. The only change made between the two tests was to the rear tyres. | ||