Boeing GA - 1 The Boeing GA - 1 ( company designation Model 10 ) were armored triplanes . Designed in 1919 , it was powered by a pair of modified Liberty engines driving pusher propellers . The first of the Engineering Division ' s heavily armored GAX series ( ground attack , experimental ) aircraft , the ponderous airplane was intended to strafe ground troops while remaining immune to attack from the ground as well as from other enemy aircraft . It was so well armored its five - ton weight proved excessive . Development . Soon after the end of World War I , the US Army sought to explore highly armored and - armed specialist ground attack aircraft . This was a pet project of General William Mitchell . The Army Air Service Engineering Division issued requests for proposals to U . S . aircraft producers on October 15 , 1919 . There were no designs offered , so the Engineering Division ordered one of its engineers , Isaac M . Laddon , to attempt what the aviation industry clearly considered impossible . His design , designated GAX , first flew at McCook Field on May 26 , 1920 . The GAX was McCook Field Project P129 and wore AAS serial number 63272 . Design characteristics . Aerodynamic cleanliness was sacrificed to fields of fire for its eight machine guns . The sturdy structure was able to carry a heavy load of ammunition along with about 2 , 200 lb ( 998 kg ) of armor plate . The result was an angular machine of wire - braced wooden construction with plywood and fabric covering . A rectangular - section fuselage carried the forward gunner in an open nose position , the pilot in a semi - enclosed cockpit with armored shutters for forward vision , and the rear gunner in an open dorsal position . The engines were carried in mid - wing nacelles . At the front of each nacelle was a gunner ' s position . As designed the armament was comprehensive . The pilot was in control of a 37mm cannon , four fixed Lewis gun s firing down and forward , and a machine gun firing forward and upward over the wings . A further two Lewis guns fired to the rear and downwards ( through a fuselage tunnel ) and a single machine gun up and over the wings . The armor covered the front half of the fuselage and the engine housings . The top wing was of larger span than the lower ones ; the middle and top planes carried ailerons . Span decreased from 65 ft 6 in to 58 ft 6 in between top and lower planes . Service . On June 7 , 1920 , Boeing was awarded a contract for 20 production models designated GA - 1 . Before the first was delivered in May 1921 , the order had been reduced to 10 . The production aircraft wore Boeing constructors numbers 200 - 209 and AAC serial numbers 64146 - 64155 . Number 64146 was evaluated at McCook as project P187 . The follow - on GA - 2 was flown at McCook field in December 1921 with orders to construct two more aircraft . The GA - 1 were sent to Kelly Field , Texas , in early 1923 for service tests with the only US aerial attack formation , the 3rd Attack Group . These tests showed the aircraft to be unacceptable . They had poor visibility and performance , particularly in rate of climb , maneuverability , and range . The aircraft suffered from noise and vibrations caused by the 3 / 16 - inch ( 4 . 75mm ) - thick armor . Take - off runs were very long by the standards of the day . The GA - 1s were extremely unpopular with the pilots conducting the evaluation . As a result , in 1925 the entire country ' s attack air force ( 3rd Attack Group that is , as differentiated from the bomber force ) consisted of fourteen Airco DH - 4 machines , inadequate even for training , lest for combat . It was rumored the GA - 1s survived until surveyed on January 14 , 1926 so Kelly Field pilots could be threatened with being forced to fly them for disciplinary infractions . All were scrapped in April 1926 .