The fuselage of the 17 was built around four ash longerons which tapered from the rectangular sheet steel engine mounting to the rudder post, with the upper longerons bowed around the cockpit, giving most of the fuselage a trapezoid cross section. This was braced with spruce struts held with diagonal bracing wires and steel plate joints. The sides and top of the forward fuselage were covered in light molded plywood panels while the rear fuselage sides were covered in fabric. Behind the pilot was a headrest, molded into the plywood top decking, which was supported by longitudinal stringers. The cowling was made of aluminium, had strengthening ribs and a pair of inset holes to provide ventilation and egress of the engine exhaust underneath. It was faired with the forward fuselage via molded side pieces. A (), resembling a spinner that didn't spin, was bolted to the front of the stationary engine crankshaft on some early examples but was generally dispensed with on later machines