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 M. Olley of Cadillac discussing the challenges of car stability and steering in side winds, specifically regarding oversteer and slip angles.
| Identifier | ExFiles\Box 170\3\ img092 | |
| Date | 6th July 1936 | |
| Exptl. Dept. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}16/KW. 6th July, 1936. M.{Mr Moon / Mr Moore} Olley Esq., The Cadillac Motor Co.Ltd., Detroit, Michigan, U.S.A. Dear Oy, We are up against the problem of making a racing car of streamline shape steer in a side wind. We understand that several makes of car have the same trouble. I seem to remember your telling me that an oversteering car would by itself turn into the wind and require the driver to put on rudder out of the wind. For understeering the other way round. Next, I remember your saying that all products of R.R. oversteer considerably. I have been taking an interest in their handling in a side wind. I have not yet been able to find a car of any make that turns into the wind. I can only think that the effect of the castor angle more than neutralises the increased slip angle of the rear tyres. Even with no castor, surely the rear slip angle must exceed the front by a large amount to move into the wind. Is it possible to arrange the slip angles so that the steering is unstable and the following sequence of events takes place: (a) Side wind causes car to drift downwind but not shift in angular position; (b) Driver puts on rudder into wind; (c) Oversteering exaggerates (b); (d) Downwind rudder required; (e) And so on. Lastly, can we by altering tyre sizes, castor angle, etc, produce a car that steers like a racing car but doesn't mind the side wind. Can we predict results from model tests in a wind tunnel. | ||