Abstract: Experimental investigation of the aerodynamic design of the vee tail featuring low RCS has been carried out. The effects of the wing dihedral angles, and aileron positions on the aerodynamic characteristics of the complete aircraft with vee tail are studied. Aircraft models with two types of vee tail and two conventional tails have been tested and the longitudinal/lateral performances compared. The results show that off-shipping moment curves are caused nonlinear by the wing with dihedral, and that the same order of off-shipping efficiency of aileron as that of its rolling efficiency is caused by the deflection of inboard aileron. Therefore, it is an important criterion that vee tail should avoid the effect of the asymmetric downwash in aerodynamic design.