Wind Tunnel Investigation of an Improved Upper Surface Blown-Flap Transport Semi-Span Model

The ASUKA was based upon the airframe of the home produced C-1 tactical transport which was modified into an Upper Surface Blowing (USB) powered high lift STOL aircraft. But the wing configuration was not changed. Therefore, this Experimental Aircraft doesn't always have the optimum configuration of a USB type aircraft. This paper describes the investigations which have been conducted to improve the aerodynamic characteristics of a subsonic jet transport semi-span model with an Upper Surface Blowing Flap system which has been newly designed using the NAL STOL-CAD program.

The tests were conducted in the NAL 2- by 2-meter Gust Wind Tunnel and results were obtained for several flap and slat deflections at engine thrust coefficients from 0 to 1.85.

As compared with the aerodynamic characteristics of the ASUKA model, we obtained the possibility of reduction of the airframe weight and significant improvement of the aerodynamic characteristics.