Non-inflammable plastic was used for the engine cowling, with aluminium sheet behind.
Other modifications included a slightly broader wing and revised aerodynamics around the cowling.
The left cowling held a combination oil tank and surface cooler.
This installation had a more pointed cowling, with more cylinder head exposed for better cooling.
In the meantime they had been upgraded with the addition of a new rudder, balanced ailerons and a cut-away cowling for better cooling.
The engine cowling and fairings are made from composites, with the cockpit doors fashioned from carbon-fibre.
Apart from a glass fibre engine cowling the fuselage is a trapezoidal cross-section semi-monocoque with plywood stressed skin and rounded dorsal decking.
The landing gear legs, fuel tank, wink tips, wheel pants, and cowling were also formed out of fibre-glass.
