PURPOSE: To counteract the inclination of an airframe resulted from the rotation al reaction force of a propeller and make the recovery of stability from rolling and yawing possible by making tabs provided on the upper and lower sides of a vertical tail to generate torque in the direction that rotates a main body in the same rotational direction as the propeller by the slip stream of the propel ler.

CONSTITUTION: The slip stream of a propeller flowing both the sides of a verti cal tail 7 alters direction when it dashes against tabs 7R and 7L, causing a force in the direction of an arrow R on the tab 7R and a force in the direction of an arrow L on the tab 7L respectively as the component force of the reaction force generated on that occasion. Since these respective forces act on the upper and lower parts of a virtually horizontal frame 5 as couple of forces, torque in the direction of an arrow T, namely, of anticlockwise rotation against the proceeding direction is generated on the frame 5, which, consequently, works to offset the anti-torque of a propeller 3 rotating in anticlockwise direction, and the liquidation of rightward inclination of the airframe and the ideal rectilin ear propagation innate to para-plane are obtained.