Abstract: Some research efforts of advancing Active Flow Control (AFC) technology to enhance the aerodynamic efficiency of a vertical tail is discussed in this paper. With the support of NASA ERA project, wind tunnel tests are performed on the synthetic jet AFC technology for 4% and 5% subscale vertical tail models at the Rensselaer Polytechnic Institute, and wind tunnel tests are conducted on oscillating jet AFC technology for 14% subscale vertical tail model at the California Institute of Technology. The latter experiment shows that 50% side force enhancement is achieved when the momentum coefficient is 1.7%. Based on research on feasibility of integrating the two AFC technologies for the aircraft system, Boeing completed a wind tunnel test (40 ft×80 ft) on a full-scale B-757 vertical tail model at NASA Ames NFAC, and found that 20% side force enhancement can be achieved using 31 oscillating jet actuator configuration at 100 knots, 30°rudder deflection, and the side slip angle ranging from 0° -7.5°. Afterwards, flight test of B-757 ecoDemonstrator equipped with 31 oscillating jet actuators is performed in the spring of 2015 with the cooperation of NASA ERA project team and Boeing. Both the pilot feedback and the result of 13%-16% side force increment confirmed the success of the oscillating jet AFC.

Key words: active flow control, synthetic jet, oscillating jet, enhanced vertical tail efficiency, wind tunnel test, flight test