A Flight Dynamics Model for a Small-Scale Flybarless Helicopter

Significance Statement

There has been considerable worldwide activity in research related to modeling and control of small-scale helicopter Unmanned Aerial Vehicles (UAVs). For low to high control input bandwidth, demonstration (or simulation) of automatic helicopter flight has been reported in numerous publications. However, none of the model-based published results are applicable for steep descent flight conditions, such as in the Vortex-Ring-State (VRS) or autorotation (i.e. helicopter flight with engine OFF). In this paper, we present a helicopter flight dynamics nonlinear model for a flybarless, articulated, Pitch-Lag-Flap (P-L-F) main rotor with rigid blades, particularly suited for small-scale UAVs. The model incorporates the main rotor, tail rotor, fuselage, and tails. This model is further applicable for high bandwidth control specifications, and is valid for a range of flight conditions, including the Vortex-Ring-State (VRS) and autorotation. Additionally, the paper reviews all assumptions made in deriving the model, i.e. structural, aerodynamics, and dynamical simplifications. Simulation results show that this nonlinear model is in good agreement with an equivalent FLIGHTLAB model, for both static (trim) and dynamic conditions. This model could potentially be used for several applications: 1) simulation of the flight dynamics of small-scale (articulated or hingeless) flybarless helicopters; 2) investigation of the coupling between main rotor blade flap/lag dynamics and main rotor inflow dynamics; as well as 3) providing a basis for model-based control design.

About the author

Skander Taamallah is a R&D engineer within the Aircraft Systems Department, of the National Aerospace Laboratory (NLR) Amsterdam, The Netherlands since 1997. His main research interests are in the fields of flight dynamics, guidance, navigation, and control methods, with applications ranging from small-scale autonomous Unmanned Aerial Vehicles (UAVs) to full-size helicopters and fighter jets. He holds a Ph.D. degree from the Delft Center for Systems & Control, Delft University of Technology (The Netherlands), a M.Sc. degree in Aeronautics & Astronautics from Stanford University (USA), and an Engineering degree in Electrical Engineering from INSA-Toulouse (France).

Flight Dynamics Model for a Small-Scale Flybarless Helicopter Advances in Engineering

Journal Reference

Dyn. Sys., Meas., Control 138(1), 011010 (2015) (20 pages).

Skander Taamallah

National Aerospace Laboratory (NLR), Anthony Fokkerweg 2, Amsterdam 1059 CM, The Netherlands.

Abstract

We present a helicopter flight dynamics nonlinear model for a flybarless, articulated, pitch–lag–flap (P–L–F) main rotor (MR) with rigid blades, particularly suited for small-scale unmanned aerial vehicles (UAVs). The model incorporates the MR, tail rotor (TR), fuselage, and tails. This model is further applicable for high bandwidth control specifications and is valid for a range of flight conditions, including the vortex-ring-state (VRS) and autorotation. Additionally, the paper reviews all assumptions made in deriving the model, i.e., structural, aerodynamics, and dynamical simplifications. Simulation results show that this nonlinear model is in good agreement with an equivalent flightlab model, for both static (trim) and dynamic conditions.

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