STOL Progenitors: The Technology Path to a Large STOL Aircraft and the C-17A

Active flow control applied to high-lift systems is a promising solution to improve low-speed flight capabilities and reduce noise emissions of commercial aircraft. However, too high power requirements in relation to the achieved lift gains have prevented active high-lift systems from being largely employed in the aeronautical industry. 
In this context, this work develops technologies to enhance the aerodynamic efficiency of an active high-lift system by means of RANS numerical simulations. 
The transonic airfoil DLR-F15 is equipped with an active internally-blown flap, which consists of a thin air jet tangentially blown over the shoulder of a simple-hinged flap deflected by 65°. To improve the lift generated by the airfoil, the effects of a flexible droop-nose device, wall suction and unsteady blowing are investigated. The fundamentals of gap-less droop-nose design are presented, describing the aerodynamic sensitivities of the main geometrical parameters and the physical phenomena that determine the lift performance. The efficiency of the resulting droop-nose configuration is also tested on a wing-body aircraft model. The analysis reveals three-dimensional flow mechanisms that limit the lift performance in operative conditions.
The airfoil efficiency is then further improved by adding a boundary-layer suction device. The effects of shape and location of the suction slot are studied to maximize the lift coefficient and pressure recovery. Finally, the effectiveness of unsteady excitation of the mixing layer by means of dynamic blowing is investigated. As a final result, a target maximum lift coefficient of 5.0 can be achieved with a 43% lower jet-momentum coefficient with respect to the baseline airfoil configuration.

Design of Efficient High-Lift Configurations with Coanda Flaps

The Upper Surface Blowing STOL aircraft named ASKA was developed and flight tested by the National Aerospace Laboratory of Japan between 1977-1989. The aircraft was a conversion of the Kawasaki C-1 medium transport, with four newly developed FJR710/600S turbofan engines on the wing. The short takeoff and landing performance, including the stability and control augmentation system and boundary-layer control, was intensively examined by the flight test. Flight-test data were obtained at altitude and converted to the standard sea level conditions to compare with the design data. From the viewpoint of the lift-and-drag and related performances, the design STOL capability was proven by the flight-test program.

Flight test of the Japanese Upper Surface Blowing STOL experimental aircraft ASKA

This paper focuses on the flight mechanical characteristics of an active high-lift supported transport-type aircraft. The presented configuration combines a boundary-layer controlled flaps system w...

Toshio Bando

Papers

Flight test of the Japanese USB STOL experimental aircraft ASKA

Flight test of the Japanese Upper Surface Blowing STOL experimental aircraft ASKA

Some Topics of ASKA's Flight Test Results and Its Future Plan

Stability and Control Augmentation System of “ASKA”