After spending an extended layup in maintenance at Boeing Field, ZA003 emerged with what at first glance looked to be a repair to the composite skin or maybe it was a change to the 787's HF antenna system? It was neither. The black, green and silver arrangement on the 787's vertical stabilizer is the first test of hybrid laminar flow control (HLFC) technology being evaluated for use on the 787-9.
HLFC is designed to reduce the drag on the leading edges of the horizontal and vertical stabilizers by sucking in the surface airflow through small holes, allowing the boundary layer to remain attached, moving the onset from smooth laminar to turbulent flow further back along the surface.
The test patch is installed in a limited area on the leading edge of the vertical stabilizer - which is built by Boeing - 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, just below the HF antenna. Boeing declined to comment on the tests.
The system, as Aviation Week's Guy Norris describes, is unlike previous testing by NASA, and the 787's system is "essentially passive":
This is important because passive systems are less complex, and lighter. Active systems, by contrast, require a turbocompressor, or other mechanical device, to suck the air into the wing.
It is believed Boeing aims to cut drag on the horizontal and vertical stabilizers by 1% for the 787-9, due for entry into service with Air New Zealand in late 2013.
The system underwent flight testing in early June at San Bernardino Airport in California and was spotted up close while on its visit. Those familiar with the system say the Boeing test includes a primer-colored perforated leading edge, pressure sensors, boundary layer rakes, the suction port at its base.
Photos Credit SBD Photo