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).
Letter to Mr. Royce regarding riding quality, comparing oscillation frequencies and the center of gravity of two different car models.
| Identifier | ExFiles\Box 43\2\ Scan210 | |
| Date | 10th November 1926 | |
| Oy13-E-111026 November 10, 1926. extra Mr. F.{Mr Friese} H.{Arthur M. Hanbury - Head Complaints} Royce, Rolls-Royce, Ltd., London, England. Dear Mr. Royce: Re Riding Quality We have recently done some interesting work in comparing two cars at the works with regard to their natural frequency of oscillation on the road springs. We think it is generally agreed that complaints of discomfort refer to the pitching frequency of the car (approximately 120 oscillations per minute) rather than the bouncing frequency of about 70-80 oscillations per minute which is of a speed to give a sensation of comfort rather than otherwise. This is obviously concerned not only with the distribution of the weight of the car (position of the center of gravity) but also with the distribution of the mass of the car, that is its radius of gyration about the center of gravity. To find the radius of gyration of the two cars, one a right-hand drive Silver Ghost with Cabriolet body and rear brakes, the other a left-hand drive Phantom with F.W.B. and large Sedan body, we swung each complete car as a pendulum about a transverse axis. Both cars were 143-1/2" wheelbase. The results we think would have been far more useful if we could have done the same for a 20 hp (but we had no car available). However our conclusions are summarized below:- (1) The C.G. of the sprung weight was further back on the Phantom Sedan than on the Silver Ghost Cabriolet. Phantom 75.875" from front axle. Silver Ghost 73.500" from front axle. | ||