EDWARDS AIR FORCE BASE,   An F-35A Lightning II conventional takeoff and landing (CTOL) aircraft rapidly expanded its high angle of attack (AOA) test envelope to its 50 degree limit in only four flights during recent flight testing here. F-35A test aircraft are limited to AOAs of 20 degrees until their controllability is proven at a higher AOA limit of 50 degrees.  The ability to rapidly progress to the maximum AOA indicates a sound aerodynamic and flight control system design. High AOA testing will continue on the F-35A for several months testing the capabilities of all design loadings and the flight control system.