The first prototype, designated as XZ-37, first flew on 29 March 1963 (other sources:29 June). It was a cantilever low-wing monoplane of tubular metal construction, the wings and stabilizers covered with duralumin and the fuselage and control surfaces made of fabric. It had a fixed undercarriage with a fully castering tailwheel, but locked to the rudders for ground handling.
The initial XZ-37 prototype made its maiden flight on 29 March 1963 (or possibly 29 June). This early aircraft had a tubular metal frame, with duralumin covering the wings and stabilizers, and fabric used for the fuselage and control surfaces. It was equipped with a fixed undercarriage and a rotating tailwheel that was locked to the rudders during ground operations.