Design and testing of devices to prevent horizontal tail stall of the Ball-Bartoe Jetwing research aircraft

Since its inception, the Ball-Bartoe Jetwing Research Aircraft has been plagued with the problems of horizontal tail stall and static longitudinal instability. The tail stall problem is primarily due to the large downwash at the tail due to the Jetwing's Upper Surface Blowing concept of propulsive lift, and due to the thin, symmetric NACA 0008 airfoil section used for the aircraft 's horizontal tail. These characteristics also contribute to the instability of the Jetwing, as do the aircraft's center of gravity and low tail volume coefficient.

Several possible aircraft modifications were examined to determine if they alleviated the tail stall and stability problems. The two most promising modifications, a leading-edge slat and a leading-edge droop device, were tested on a quarter-scale half span model of the Jetwing horizontal tail in the University of Tennessee Space Institute's Low Speed Wind-Tunnel .The results of these tests show that while both the slat and droop configurations improve the Jetwing's horizontal tail stall capabilities, neither modification affected the aircraft's stability problem significantly.