 They all had imported engines fitted, but trialled various small improvements for the production aircraft that included cooling vents for the crankcase, introduction of a pitot tube and static vent in the starboard upper wing, a faired headrest for the pilot, and a metal propeller whose pitch could be adjusted on the ground.The I-5 was a single-seat biplane with the upper wing slightly larger than the lower, and a fixed landing gear with a tailskid.The aircraft was of mixed construction, with the fuselage being made of a framework of welded steel tubes covered by a fabric skin over the rear fuselage, with the front fuselage section being covered by detachable duralumin panels as far back as the rear of the cockpit.