Evaluation of viscous drag reduction schemes for subsonic transports

The results are described of a theoretical study of viscous drag reduction schemes for potential application to the fuselage of a long-haul subsonic transport aircraft. The schemes which were examined included tangential slot injection on the fuselage and various synergetic combinations of tangential slot injection and distributed suction applied to wing and fuselage surfaces. Both passive and mechanical (utilizing turbo-machinery) systems were examined. Overall performance of the selected systems was determined at a fixed subsonic cruise condition corresponding to a flight Mach number of free stream M = 0.8 and an altitude of 11,000 m. The nominal aircraft to which most of the performance data was referenced was a wide-body transport of the Boeing 747 category. Some of the performance results obtained with wing suction are referenced to a Lockheed C-141 Star Lifter wing section. Alternate designs investigated involved combinations of boundary layer suction on the wing surfaces and injection on the fuselage, and suction and injection combinations applied to the fuselage only.