Full-speed flap fish tail fin

The utility model relates to a full-speed flap fish tail fin which comprises a main wing, a flap, a flap shaft, a main wing hinged support and a flap hinged support. The fin shaft of the main wing and the flap shaft of the flap anticlockwise rotate by a preset included angle by taking the intersection point of the axis of the fin shaft and the fin root as well as the intersection point of the axis of the flap shaft and the fin root as the center; the fin shaft and the flap shaft are arranged in parallel; the main wing hinged support is arranged at the bottom end of the main wing, the flap hinged support is arranged at the top end of the flap, the flap shaft penetrates through the main wing hinged support, the flap hinged support is connected with the main wing and the flap, and the main wing and the flap can relatively rotate around the flap shaft. Under the condition that the aspect ratio of the fin is kept unchanged, the lifting force generated by active flapping of the fin under the working condition of fu