Advanced Helicopter Rotor Control Phase I SBIR Project funded by US Army

Helicopter rotors typically operate in a highly unsteady aerodynamic environment. In forward flight, the rotor blade sections experience large variations in angle of attack over one revolution. This is the primary source of a variety of problems such as high vibration levels and retreating blade stall. Actively changing the angle of attack of the blade sections as a function of azimuthal position has been shown to significantly alleviate vibration levels as well as improve aerodynamic performance of the rotor. The change in angle of attack can be accomplished in a variety of ways. High bandwidth hydraulic actuators in the rotating frame that can actively change the root pitch of the rotor blades have been demonstrated in scale models and in full scale tests. However, implementation of such systems in production helicopters is a challenging task due to the complexity of the system, and the increase in maintenance associated with the large number of moving parts as well as the hydraulic slip ring.



Techno-Sciences, Inc. (TSi), has assembled a collaborative development team of TSi, the Smart Structures Laboratory of the Alfred Gessow Rotorcraft Center at the University of Maryland, and our commercialization partner, Bell Helicopter Textron to develop an innovative Active Conformal Camber Actuator (ACCA) Technology for improved rotor performance. The ACCA effectively consists of a piezohydraulic pump coupled to hydraulic artificial muscle (HAM) actuators that deform a honeycomb structure covered with a flexible skin. In the piezohydraulic actuator, the high frequency, low stroke of the piezoceramic stacks is converted into a lower frequency, higher stroke output from the hydraulic actuators. The result is a solid state piezoceramic actuator with both high force and high stroke capability that is ideally suited to the force and stroke requirements for adaptive camber control. While conventional hydraulic cylinders embedded in the rotorblade have been used in the past to actuate a trailing edge flap on a model scale rotor, the present approach eliminates the need for a hydraulic slip ring, and replaces the rigid hydraulic cylinders with flexible HAM actuators that conform to the airfoil shape.

Download the spec sheet for TSI Pneumatic Actuators

PAM_brochure