The object of this thesis is to determine the directional stability of a tricycle-geared aircraft during the landing roll. The motion of the aircraft is simulated by a computer program based on the appropriate equations of motion. Empirical aircraft and tire data are utilized in order to improve the simulation process. The stability of the aircraft is obtained by analyzing the motion of the vehicle after an initial disturbance about the vertical axis of the aircraft. The influence of the aircraft's velocity and other parameters on the stability is then determined. For the single-engine Cessna, the results show that a steady-state yaw angle is obtained after an initial disturbance. The results are presented graphically to show the effect of various parameters on the aircraft's stability. / Master of Science