Identification Modeling and Analysis of the Coupled Drive-Train/Inflow in Miniature Rotorcraft Axial Flight Dynamics

Helicopters exhibit significant nonlinearities in their dynamic behavior that can be challenging for automatic control. The main rotor and the engine/drive train system are important sources of nonlinearities. Effects of these nonlinearities are noticeable when performing aggressive maneuvers both in heave and in translational flight. To better understand these effects and determine ways to develop appropriate models for control design and simulation we performed a series of in-flight experiments including, rotor inflow measurements and load tests in hover flight, and vertical maneuvering flight. We used a small-scale coaxial helicopter (Blade CX) in our indoor flight test facility. This paper describes the flight experiments illustrating these effects and the preliminary modeling and analysis.