The main wing (2) has a shaped recess (10) under the rear profile into which the secondary wing profile is located during normal flight, to form a complete wing profile with the main wing. For take-off and landing this secondary wing is extended away from the main wing by two support struts (5) hinged between the wings i.e. the wing shape becomes a biplane. The support struts are fitted with servo cylinders at each end to control the extension and to control the relative pitch of the two wings. Additional adjustable flaps (3, 7) at the trailing edges of the two wings enable the aircraft to be trimmed. The extended wing setting can also be used to improve slow speed manoeuvrability.
