Composite design features revised high-lift system compared with previous variants - and folding tips

The launch of flight-testing of the Boeing 777-9 provides the opportunity to examine how one its most significant changes– the all-new carbonfibre wing - compares with that of its predecessor.

777-9 first flight wing trailing edge

Source: Boeing

The new 777X family, of which the -9 is the first variant, features a larger wing with span increased by 7m (23ft) over the 777-300ER, to 71.8m (above). This huge span is the reason for its most notable feature - folding wingtips (below) - which is a first on a commercial aircraft. When folded, the 777X span reduces by 7m to 64.8m to ensure airport compatibility.

Boeing 777-9 folding wingtip

Source: Boeing

Boeing describes the 777X wing as a “fourth-generation composite” design, incorporating an “advanced high-lift” system. The new wing’s trailing-edge system is similar in concept to its predecessor’s, with some interesting changes.

777X wing 777-300ER wing comparison

Source: Boeing

The 777X wing (top) has greater span and revisions to trailing edge, compared with earlier -300ER design (bottom)

Both generations have inboard double-slotted and outboard single-slotted flaps (above). But due the greater span of the outboard trailing edge, the 777X’s outboard flap comprises two sections, compared with one on the earlier generation. Each flap section incorporates two actuator/canoe fairings, meaning it has double the number of the original 777.

The inboard flaps on the 777X have greater span than the original version. As a result, the flaperon installed between the inboard and outboard flaps has moved further outboard into the more swept part of the wing trailing edge.