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This chapter presents a fully coupled 2D fluid–structure interaction (FSI) simulation of PZL W3 Sokol main rotor blade. Loosely coupled simulation is performed using ANSYS Fluent and MSC Nastran solvers in separate domains with a custom coupling tool developed at PZL Swidnik for load transfer between the domains. A computational fluid dynamics (CFD) mesh deformation interpolation method based upon Nastran structural solver is proposed. By variation of the interpolator parameters, high quality of the deformed mesh can be achieved with controlled level of cell distortion. Such mesh deformation approach is quite easy to implement and computationally effective yet allowing for robust distortions transfer for a wide range of blade rigid body motions as well as surface deformation with minor fluid mesh quality degradation.

"Fixed and rotary wing pilots alike are familiar with potential instabilities or with annoying limit cycle. oscillations that arise from the effort of controlling aircraft with high response actuation systems. Understanding, predicting and suppressing these inadvertent and sustained aircraft oscillations, known as aircraft (rotorcraft)-pilot couplings (A\/RPCs) is a challenging problem for the designers. The goal of the. present paper is to give an overview on the state-of-the-art in RPC problem, underlining the future. challenges in this field. It is shown that, exactly as in the case of fixed wing APCs, RPCs existed from the beginning of rotorcraft development and that the problem of eliminating them is not yet solved: the current rotorcraft modelling for RPC analysis is rather limited to the particular case analysed and there is. a lack of quantitative pilot behavioural models to analyse RPCs. The paper underlines the importance of involuntary pilot control actions, generally attributed to biodynamic couplings in predicting RPCs in rotorcraft. It is also shown that recent experiences demonstrate that modern rotorcraft seem to embed. tendencies predisposing the flight control system FCS system towards dangerous RPCs. As the level of automation is likely to increase in future designs, extending to smaller aircraft and to different kinds of. operation, the consequences of the pilot ‘fighting’ the FCS system and inducing A\/RPCs needs to be eradicated. In Europe, the ARISTOTEL project (2010–2013) has been launched with the aim of understanding and predicting modern aircraft's susceptibility to A\/RPC. The present paper gives an overview of future challenges to be solved for RPC-free design and some new solutions herein.. "