What is the AV-8B's wing made of?

Engineers designed a new, single-piece supercritical wing that improves cruise performance by delaying drag rise and increasing the lift-to-drag ratio. The wing is almost entirely graphite-epoxy. Made from composites, it is thicker and has greater span than the AV-8A's wing. The structure of that new supercritical wing, the largest aircraft part made of composite material up to that time, weighed 1,374 pounds including control surfaces yet to be fitted; the spars and upper and lower skins are graphite-epoxy and save 330 pounds compared with conventional materials.

Compared with the AV-8A's wing, it has a greater aspect ratio, less sweep (from 40° to 37°) and an area that grows from 200 sq ft (18.6 m²) to 230 sq ft (21.4 m²). Being almost entirely composite, it is 330 lb (150 kg) lighter than the AV-8A's smaller wing. The new supercritical wing also provides more fuel volume, more load-carrying capacity and greater cruise efficiency than the AV-8A's. With the leading-edge root extensions, it allows a 6,700 lb (3,035 kg) increase in payload over first-generation Harriers after a 1,000 ft (300 m) takeoff run.

26% of the aircraft's structure is made of composite materials, reducing its weight by 480 lb (217 kg) compared with a conventional metal structure. Weight was also reduced with a composite forward fuselage, stabilizers and parts of the rear fuselage.