F-35B BF-4 Flies STOVL Mode

BF-4, the fourth F-35 short takeoff/vertical landing (STOVL) test aircraft, flies mode 4 for the first time on April 7, 2011, at Naval Air Station Patuxent River, Md. Mode 4 engages the F-35 STOVL’s shaft-driven LiftFan system that allows the aircraft to hover, perform short takeoffs and land vertically. BF-4 is the first aircraft equipped with full mission systems to fly mode 4.