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Japan Aerospace Exploration Agency

Eco-wing technology


December 22, 2014

Verification of the effect of applying Krueger flaps

A car equipped with model Krueger flaps. It was preliminarily driven at the Tsukuba Space Center.

JAXA is undertaking research to reduce fric tion drag on wings and improve the fuel efficiency of aircraft.

It is known that an effective way to reduce friction drag is a natural laminar flow design that maintains laminar boundary-layer flow*1 over the surfaces of the wing. However, because insects get stuck to the leading edge of aircraft wings during landing and takeoff, the effect of natural laminar flow design may be reduced. Therefore, we have applied Krueger flaps*2 to the leading edge of the wing and tested its effectiveness at preventing insects and other materials from sticking.

In an experiment conducted in October 2014, a model was created with Krueger flaps with different cross-sections arranged side-by-side and placed atop an automobile, which was then driven. The results confirmed that the effectiveness of preventing insects from sticking differs depending on the shape of the Krueger flap's cross-section and its positional relationship with the main wing to which it is attached.

The results of this experiment will lead to the development of technology to maintain smooth leading edges of wings in order to reduce friction resistance.

This experiment was conducted with public donations given during fiscal 2013.

*1:Refers to a state in which air flows evenly and smoothly over the surface of a wing.
*2:A forward flap device to generate lift for the wings. Such flaps are stored under the wing when cruising, then deployed in front of the wings while landing to generate the necessary lif t at lower speeds.