Boeing has begun flight testing a hybrid laminar flow control (HLFC) surface aboard one of its 787 test aircraft, aimed at cutting the drag of its 787-9 horizontal and vertical stabilisers.

The HLFC modification is installed on test aircraft ZA003 in a limited area on the leading edge of the Boeing-built vertical stabiliser, one-quarter to one-half of the way up the fin, estimated to be positioned on the adjacent forward panels between ribs 3 and 7, and below the HF antenna.

Boeing declined to comment on the tests.

It is believed that Boeing aims to cut stabiliser drag by 1% for the upcoming -9 model, due for entry into service in late 2013.

HLFC surfaces are designed to suck in the surface airflow, allowing the boundary layer to remain attached, moving the onset from laminar to turbulent flow further back along the surface, reducing overall drag.

Testing on aircraft ZA003 began on 9 June in San Bernardino, California, after an extended period of maintenance lay-up.

Boeing has already employed a natural laminar flow surface on the 787's engine nacelles, although the hybrid system - if implemented on the larger -9 - would represent the first commercial application of HLFC technology.

Unlike the -8 horizontal stabiliser built by Alenia Aeronautica, the 787-9's tail will be built entirely by Boeing, as the airframer looks to reduce weight and improve manufacturability with an integral multispar box design that will see the spars and skins of the main stabiliser boxes being co-cured together.

Source: Flight International