The US Army's GAX programme was an early attempt at an armoured ground attack aircraft, to be fitted with a 37-mm cannon firing through the propeller hub. Built by the Aeromarine Plane and Motor Company of Keyport, New Jersey, the PG-1 was, not surprisingly, a poor performer and unpopular with Army test pilots. The first of three machines delivered to the USAAS, 64245 is seen wearing McCook Field project number P-240.