Active Pitch Link

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APL in whirl tower

Active Pitch Link


Actively Controlled Flap


Hybrid Control Concept


Analyses & Simulations


Composite Rotor Blades








Active Pitch Link








The Active Pitch Link (APL) is the first novel, patented, and only piezoactuator-based, all-electric, high frequency active pitch link in the world. It offers a reduction of vibration of 90% in a fail-safe manner.


The APL is a stiffness control device, which is the only existing active control system designed deliberately to alter the blade root stiffness for vibration reduction in helicopters.






The Active Pitch Link (APL) is designed to replace a conventional pitch link on helicopter, which is inserted between the blade horn and the rotor swashplate, to perform Individual Blade Control (IBC) and reduce the transmitted vibration between the rotating to the non-rotating frames on a helicopter.


Based on state of the art computational models developed over several years of research, the form factor and performance characteristics of the APL can be easily scaled to meet different sizes and use requirements without any compromise to performance.








The Active Pitch Link has been tested for over 50 hours at the Whirl Tower Test Facility and confirmed 90% reduction of vibration of the 2/rev [N+1/rev] vibrations.





Periodic controlled vibrations have been generated by an implemented fan-system, with 14 m/s upwash and 20 degrees azimuth rotor radius in the rotating frame. The test results show that while the 1/rev vibratory load (corresponding to cyclic control in our system) remains largely unchanged, the 2/rev vibration is reduced by >90%.






competitive advantage