Tail-wheel aircraft exhibit more P-factor during the ground-roll than aircraft with tricycle landing gear, because of the greater angle of the propeller disc to the vertical. P-factor is insignificant during the initial ground roll, but will give a pronounced nose-left tendency during the later stages of the ground roll as forward speed increases, particularly if the thrust axis is kept inclined to the flight path vector (e.g. tail-wheel in contact with runway). The effect is not so apparent during the landing, flare and rollout, given the relatively low power setting (propeller RPM). However, should the throttle be suddenly advanced with the tail-wheel in contact with the runway, then anticipation of this nose-left tendency is prudent.