The Auster AOP.9 was designed as a successor to the Auster AOP.6. Like its predecessor, it was a braced high-wing single engined monoplane with a fixed tailwheel undercarriage. Although having the same general appearance, the AOP.9 was a new design, with larger wing area and a more powerful engine. The wing and tail were metal-skinned, but the fuselage and ailerons were fabric-covered. The fin and rudder assembly were more angular in the new aircraft with a noticeable dorsal fillet. A combination of the more powerful 180 hp Blackburn Cirrus Bombardier engine, larger wings and large flaps gave it an improved take-off and landing performance compared with the AOP.6. It could operate from ploughed fields and muddy surfaces using low pressure tyres and strengthened undercarriage. The cabin held three seats, pilot and passenger side-by-side and the observer behind, facing either forwards or rearwards. The aircraft was also designed to be convertible into a two-seat light transport with an interchangeable rear floor. In this configuration the observer sat alongside the pilot. The prototype WZ662 first flew 19 March 1954. Auster Aircraft allotted its model designation B5 to the AOP.9 design.
Operational history
Deliveries started to the Royal Air Force in February 1955, replacing AOP.6s in the regular AOP squadrons, the auxiliary squadrons disbanding in March 1957 before receiving AOP.9s. Until the formation of the Army Air Corpsin September 1957, Army personnel flew RAF aircraft based in RAF squadrons. The aircraft were in action with No. 656 Squadron from September 1955, flying an average of 1,200 sorties per month. By the end of Operation Firedog in Malaya on 31 July 1960, 656 Squadron's AOP.6 and AOP.9s had carried out 143,000 sorties. The AOP.9s were involved in several of Britain's other end of Empire conflicts; 653 Squadron AAC used them in Aden in the early 1960s, flying from Falaise, Little Aden. They stayed in service until 1966 and were the last fixed wing AOP aircraft used by the AAC, though their light transport role was taken over by Beavers. The South African Air Force operated its AOP.9s from 1957 to 1967. The Army Historic Aircraft Flight maintain an AOP.9 in flying condition at Middle Wallop. In the 1970s, 19 AOP.9s joined the UK civil register, and in 2008 14 remained, though only about three of these had a current certificate of airworthiness. The sole Beagle E3/Auster AOP.11 G-ASCC was flying until an accident in 2007.
Variants
;Auster AOP.9 in September 1961 ;Auster AOP.11 ;Auster 9M
