Hybrid Control Concept

You are here: Home » Hybrid Control Concept

APL in whirl tower

Active Pitch Link


Actively Controlled Flap


Hybrid Control Concept


Analyses & Simulations


Composite Rotor Blades








Smart Hybrid Active Rotor Control Systems (SHARCS)





Hybrid Control Concept




The major advantage of any actively controlled system is its adaptability, i.e. its ability to control vibration (or noise) at various flight regimes. This is accomplished by different actuation schedule for reduction of different types of vibration (i.e. Blade Vortex Interaction (BVI) vibration, cabin vibrations, rotor imbalance vibrations) as well as noise (i.e. BVI noise).


It has been proven that  with one single system (such as the Actively Controlled Flap), one cannot control two phenomena simultaneously. For example, cabin vibrations and BVI noise could not be reduced at the same time.


What worse: in many cases not just that one cannot control two phenomena at the same time, but when one phenomena is reduced, the other becomes deteriorated, e.g. when vibration is reduced, noise increases and vice versa.









The proposed hybrid control concept aims to address this shortcoming. The baseline idea of “hybrid control” is to use two or more independent control systems on a single rotor blade. Thus, when one is optimized to reduce vibration, the other one can be optimized to reduce noise or yet another mode of vibration (such as cabin vibration or rotor imbalance). Thus, the hybrid control concept promises to achieve simultaneous reduction of vibration and noise.


A specific aspect of the hybrid control concept is that it is based on combining not just two flow control systems (i.e. any two of the ACF, ATR, ACT) but a flow control and a structural control system, where structural control means “stiffness control” of the blade root –  Active Pitch Link.


Furthermore, hybrid control concept promises to improve the efficiency of Flow Control devices by adaptively lowering the torsional stiffness of the blade with the aid of a structural control device.