An aircraft (1) having a fuselage (2), the aircraft (1) comprising a rotary wing (9) above the fuselage (2) and an extra fixed wing (10), the rotary wing (9) being above both the fuselage (2) and the fixed wing (10), said fixed wing (10) comprising at least one closed wing (20) comprising a first half-wing (21) and a second half-wing (22). Each half-wing (21, 22) is provided with a top lift portion (30) and a bottom lift portion (40), said bottom lift portion (40) of a half-wing being arranged in the wake (S) of the top lift portion (30) of that half-wing, the wake (S) being generated by a stream of air (F) coming from said rotary wing (9) and impacting against the top face (30′) of the top lift portion (30) when said aircraft (1) has a forward speed less than a predetermined threshold.