DIRECTIONAL STABILITY AND CONTROL OF A FOUR - WHEELED VEHICLE IN A FLAT TURN 600208
The directional stability and control of a four-wheeled vehicle is studied by means of a simplified analysis which takes into account the variation of the cornering performance of the tires with changes in their vertical loading. A detailed investigation is made of the steady, flat turn in order to appraise the effects of turn radius and forward speed on steering characteristics and dynamic directional stability.
The results of exploratory calculations are presented for a vehicle series in which the fore-and-aft location of the center of gravity is varied; also, a variety of tire configurations and inflation pressures are used on the front and rear wheels. It is shown that both turn radius and speed substantially affect the directional stability and control characteristics of the vehicle. In particular, it is demonstrated that calculations based on straight runs are not indicative of the performance in turns. Vehicles displaying acceptable driving characteristics at low speeds and large turn radii may exhibit oversteering and directional instability in tight, high speed turns.
The calculations also bring to light a variety of interesting conclusions regarding the influence of c. g. location, tire tread width, and tire inflation pressure on the directional performance of vehicles.