State-Space Inflow Model Identification and Flight Dynamics Coupling for an Advanced Coaxial Rotorcraft Configuration
Sean Hersey, Roberto Celi, Ondrej Juhasz, Mark B. Tischler, Omri Rand, Vladimir Khromov
May 8, 2017

State-Space Inflow Model Identification and Flight Dynamics Coupling for an Advanced Coaxial Rotorcraft Configuration
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- 18 pages
- SKU # : 73-2017-0168
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State-Space Inflow Model Identification and Flight Dynamics Coupling for an Advanced Coaxial Rotorcraft Configuration
Authors / Details: Sean Hersey, Roberto Celi, Ondrej Juhasz, Mark B. Tischler, Omri Rand, Vladimir KhromovAbstract
In order to consider the stability and controllability of advanced coaxial configurations, a better understanding of the aerodynamic interactions between rotors is required. Modern aerodynamic analysis tools such as free wake models can accurately model the behavior of the inflow of a coaxial configuration, without the inclusion of theoretical limitations and approximations used by classical-simplified schemes. They are not, however, expressed in state-space form and therefore can not be readily analyzed as a linear flight dynamics problem and are often computationally expensive. The objective of this paper is to extend a system identification method, which was previously validated for single main rotor helicopters, to the extraction of state-space linearized models from computed inflow data acquired from free wake models of a coaxial rotor in hover. Also a key extension of the identified inflow systems is shown to model inflow off of the rotor plane as a output equation of the inflow system, or as its own ODE inflow system. With state-space models of inflow defined for an advanced coaxial configuration, this paper also presents a study of the fully coupled aircraft flight dynamics, showing key effects of rotor inflow on the dynamics of a coaxial rotorcraft configuration.