Sikorsky Tests Active Rotor with Flaps
Sikorsky Innovations has completed wind-tunnel testing of an active rotor system equipped with “high authority” flaps, thus paving the way for improvements in noise, vibration and–marginally–efficiency on future rotorcraft. A 28-foot-diameter S-434 production main rotor retrofitted with the flaps was tested in a NASA wind tunnel. Electromechanical actuators were used to move the trailing-edge devices. The system performed “extremely well over a variety of forward flight conditions up to 140 knots,” according to the company. Goals were met in noise (-6dB) and vibration (-20 percent). Performance was improved, too. “Our active flap rotor is more effective on noise and vibration than on cruise efficiency,” said Russ Gray, chief engineer for advanced programs. Sikorsky claims to have a much higher-authority system than the one Eurocopter test flew in 2005. The U.S. helicopter company said its design can deflect by up to plus or minus 10 degrees and “is not limited to low frequencies.” Moreover, the flap can move up to five times for every rotation of a blade.