Laminar flow control leading-edge systems in simulated airline service

Abstract

Achieving laminar flow on the wings of a commercial transport involves difficult problems associated with the wing leading edge. The NASA Leading Edge Flight Test Program has made major progress toward the solution of these problems. The effectiveness and paracticality of candidate laminar flow leading edge systems were proven under representative airline service conditions. This was accomplished in a series of simulated airline service flights by modifying a JetStar aircraft with laminar flow leading edge systems and operating it out of three commercial airports in the United States. The aircraft was operated as an airliner would under actual air traffic conditions, in bad weather, and in insect infested environments. Two leading edge systems were flown. One used a perforated titanium suction surface with approximately 1 million, 0.0025 inch diameter, electron beam drilled holes to maintain laminar flow on the wing upper surface to the front spar. This leading edge also had a Krueger-type flap which served as a protective shield against insect impacts. The second leading edge had suction through a slotted titanium skin with 27 spanwise slots (about 0.004 inch wide) on the upper and lower surface; fluid dispensed through some of these slots near the attachment line provided wing surface wetting during takeoff to protect against insect impacts. Both leading edges were equipped with de-icing and fluid purge systems.