The engine cowling, rear fuselage and top decking are of fibreglass. These featured a Vokes air filter in a large "chin" fairing under the engine cowling. The B-2 also had an oil hydraulic system for closing the cowling flaps. The aircraft's structure is mostly aluminum with a fiberglass cowling. The later three-seat 47H had an enclosed cabin with full cowling and monocoque tail boom. A supercharger intake was centered on the top decking of the engine cowling. These aircraft were distinguishable by the addition of vents in the cowling face. The new powerplant requires a new cowling and baffles. The AP-4's big spinner was later removed and a new tight cowling fitted. They were also armed with two Breda-SAFAT machine guns mounted above the engine cowling. The standard XP cowling with adjustable mirrors and gauges returned. This resulted in an extensively modified cowling and nose for the aircraft. Some aircraft had their entire cowling thus painted. The VR-01 was also given a "shark fin" engine cowling. This was for fuel leaking from the auxiliary power unit cowling.