Effect of flaperons on a biplane configuration

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Johnson, Bonnie L.

The use of full span flaperons on low speed biplane configurations i~ a unique synergistic concept that has yet to be evaluated. The well-executed biplane configuration is useful for performing low speed aerobatics, providing the benefit of relatively low induced drag at high load factors along with high roll rates, important parameters in performing smooth and efficient aerobatics. Since the conventional use of flaps in the presence of ailerons would decrease the span of the ailerons, it seemed beneficial to the biplane configuration to combine the flap and the aileron into a full span flaperon. Biplanes historically have had poor forward visibility in the landing configuration; the use of full span flaperons would improve the aircraft attitude in the landing phase without significantly compromising its roll rate capability. The biplane configuration, a 1/5 scale model of the Merkel Mark II Maverick, was tested in the Wichita State University 7 X 10 Foot Low-Speed Wind Tunnel at a Reynolds Numbers of 922,000. The flaperon data are presented for deflections from -8 · to 16 degrees. Tail on and off data are presented to show the biplane was still trimmable with flaperons deflected symmetrically. Evaluation of the wind tunnel results indicates that the flaperons would be beneficial to improving the landing attitude for improved visibility at a given approach speed without loss of lateral control. Also, for improved high "g" maneuvering performance, the full span flaperons showed a reduction in both the profile and the induced drag at symmetric deflections of -4 degrees.

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Thesis (M.S.)-- Wichita State University, College of Engineering, Dept. of Aerospace Engineering