A helicopter is described comprising a fuselage elongated along a first axis and extending between a nose and a tail boom; a tailplane with a pair of first aerodynamic surfaces elongated along a second axis; the first and second axis define a first plane; the helicopter comprises a pair of elements transversal to the first aerodynamic surfaces; and a pair of second aerodynamic surfaces generating respective second aerodynamic forces, connected to first elements, and facing and spaced from respective first aerodynamic surfaces; each second aerodynamic surface comprises one first root end connected to the respective said element, a second free end spaced from said tail boom, a first leading edge, a first trailing edge opposite to said first leading edge, a first chord at said first root end and a second chord at said second free end parallel to said first axis; the first and the second chord define a second plane tilted with respect to said first plane.