Auster AOP 9
The AOP.9 was a completely new aircraft and not a development of a civil type. On the insistence of the British Army the fuselage is welded steel and fabric covered. A third seat can be fitted. A unique feature is the rear cockpit floor, designed to allow a complete and rapid change of role. With the removal of six bolts the floor may be lowered out of the aircraft and a new floor, complete with equipment, can be substituted in a few minutes.
Apart from plastic tips and a fabric covering aft of the main spar, the wings are all-metal and are built round a stiff leading-edge torsion box. The split flaps have a hydraulic assist. Drooping ailerons assist with short landings and take-offs. One of its main features is the Dowty liquid‑spring undercarriage with large‑diameter tyres, capable of withstanding a vertical rate of descent of 9 ft/sec and allowing operation from virtually any type of landing surface.
The Auster A.O.P. Mk. 9 first flew on 19 March 1954 with a 180 hp / 134kW Blackburn Cirrus Bombardier 203 (military version of 702) engine.