The Grumman JF Duck was manufactured from 1934 until 1936, when production switched to the J2F Duck and later variants.[1] The more obvious external appearance clue to distinguish a JF from an early J2F is the deletion of the inter-aileron strut between the wings on the J2F; less noticeable perhaps is the J2F's slightly longer rear fuselage/float joining fillet beneath the tail.[1]The Duck's main pontoon was part of the fuselage, almost making it a flying boat, though it appears more like a standard aircraft with an added float. This general configuration was shared with the earlier Loening OL. The XJF-1 prototype first flew on 24 April 1933 piloted by Grumman test pilot Paul Hovgard