Researchers at the California Institute of Technology (Caltech) and the University of Arizona received a NASA group achievement award for a full-scale wind-tunnel test that proved the feasibility of active flow control. The system has been designed to blow air on the tailfin surface, making it more effective at low speed and enabling the vertical empennage to be smaller.
On trial at the Moffett Field facility was a Boeing 757 tail, and results confirmed that sweeping jet actuators could increase the airflow around the rudder sufficiently to steer the airplane in the event of an engine failure. The actuators were installed under the skin of the tail, along its vertical length.
With such a system installed, aircraft manufacturers could thus reduce tail size by 20 percent, according to project manager Emilio Graff. This would translate into reduced drag and weight. The sweeping jet actuators, powered by the APU, would need to be activated only during the low speeds of takeoff and landing. Boeing plans to flight-test the system on its ecoDemonstrator 757 next year.