DOW-UNITED Technologies Composite Products (Dow-UT) has delivered the first ship-set of 44 sine-wave spars for the Lockheed Martin/Boeing F-22 wing. The spars were produced using an advanced resin-transfer moulding (RTM) process developed by Dow-UT (Flight International, 24-30 January).

Boeing, which is responsible for the F-22 wing, calculates that advanced RTM will save an average of some $250,000 an aircraft, compared with hand lay-up of composites, based on an anticipated purchase of 442 F-22s.

"Compared with other forms of composites manufacturing, the Dow-UT method also significantly reduced required manufacturing time and increased the quality of the parts," says Boeing. Under a $30.2 million contract, Dow-UT is producing the spars and some 100 other parts for the first 11 development F-22s. In RTM, resin is injected into a closed mould containing a pre-form of dry fibres.

Source: Flight International