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).
Vehicle handling characteristics, focusing on experiments to induce understeer.
| Identifier | ExFiles\Box 155\4\ scan0028 | |
| Date | 11th March 1937 | |
| -2- Rm.{William Robotham - Chief Engineer} tried the car like this just before going to the States. He agreed about the improvement in handling. The car wandered very much less than an ordinary Bentley. It was no longer necessary to slow down when meeting an approaching car on a narrow road. At first we could not obtain pronounced understeer at a front tyre pressure of more than 25 lbs. We, therefore, tried two of the other methods applicable to a car with orthodox springing. Firstly, lowering the rear end of the front springs, and, secondly, lowering the front end of the rear springs. Both these experiments provide understeer because the axles become inclined to their normal direction when the car rolls. Although understeer was evident on the skid pan the car on the road changed its direction during independent movement of any of the wheels, making it very unpleasant to drive. This line of attack was, therefore, of no use. The remaining lines of development are:- (1) An increase in rolling rate of the front of the car. (2) A search for a type of tyre which can be fitted to all four wheels, and by suitable adjustment of pressures provide understeer without making the steering heavier or spoiling the ride. The weather greatly affects the use we can make of the skid pan. It is often under water. Some of this drains from the surrounding land up through the expansion joints on to the pan. We have done all our recent testing round the banking. It seems we shall have to continue using the banking till finer weather arrives. The disadvantage is that we have no margin of safety for an unexpected skid. The original purpose of the banking was to provide a safety zone for getting out of trouble. We have tested many other cars on the pan to get information of how they behave. The Bentley car fitted with Gordon Armstrong independent front suspension understeered. On the road it handled very well, the steering being far more accurate than a standard Bentley. The preliminary results of | ||