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).
Determining the moment of inertia for various car body types and the effects of weight distribution on spring suspension.
| Identifier | ExFiles\Box 43\2\ Scan150 | |
| Date | 4th May 1926 | |
| Oy1-L-5426 -3- May 4th, 1926 III. (b) We have been considering whether we ought not to take off the axles and swing cars with each of our 6 typical body types as a pendulum from a beam in the roof in order to get an accurate figure for the moment of inertia of each type. We wish to suggest that by doing this and adjusting weight on each body so as to bring about the relation K² = ab, it would then be possible to mount the body, so altered, on its axles, and ascertain on the road whether a benefit in riding was actually obtained by making the spring suspension independent at either end. IV. If all the spring mass of the car were concentrated above the two axles, K² would be equal to a.b. With four passengers in the car (12-MC) giving sprung weights of 2420 front and 2680 rear, "a" would be 6.570 feet, "b" 5.930 feet, and K² = 39 feet ². Obviously it is something considerably less than this on all our cars, and if 30 feet² is a reasonable approximate figure with 4 passengers we find that the C.G. of the car should be only 3.25 feet from either the front or the rear end of the car. Obviously this is quite impossible, and therefore apparently the only way in which the springing can be made independent either end is by concentrating the weight so far as possible above the two axles by moving the battery to the front, spare wheels to the rear etc. so as to increase the moment of inertia as much as possible. V.{VIENNA} We wonder whether it would be useful to England if we took cars of several standard body types and swung them as suggested above in order to obtain their moments of inertia. Possibly it could be arranged to do this on imported Phantom cars with standard coachwork. Oy. MO/E | ||