United Aircraft (UAC) subsidiary AeroComposite has delivered the first centre wingbox for the Irkut MC-21 - with the nar-rowbody scheduled to complete first flight by the end of the year. The centre wingbox and wing skins of the MC-21 are two of the most interesting aspects of the development programme. Irkut selected an out-of-auto-clave manufacturing process to cure the epoxy resin for both structures. Although such vacuum-assisted resin transfer infusion processes have become common in very small aircraft, it is the first time a manufacturer has attempted to avoid autoclave curing for the primary structure of a large, passenger-carrying aircraft intended to receive civil certification. The out-of-autoclave process is expected to dramatically reduce manufacturing costs compared to an autoclave curing pro- cess. The lightweight composite material is also expected to improve fuel efficiency by reducing the weight of the airframe and allowing designers to craft a more advanced wing with a higher aspect ratio than permitted by metallic structures. An Antonov An-124 freighter delivered the centre wingbox from the AeroComposite plant in Ulyanovsk to the Irkust Aviation Plant, where Irkut is assembling the first MC-21-300.
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