# Flight Dynamics Simulation Modeling and Control of a Large Flexible Tiltrotor Aircraft

 dc.contributor.advisor Celi, Roberto en_US dc.contributor.author Juhasz, Ondrej en_US dc.date.accessioned 2014-06-26T05:37:36Z dc.date.available 2014-06-26T05:37:36Z dc.date.issued 2014 en_US dc.identifier.uri http://hdl.handle.net/1903/15460 dc.description.abstract A high order rotorcraft mathematical model is developed and validated against the XV-15 and a Large Civil Tiltrotor (LCTR) concept. The mathematical model is generic and allows for any rotorcraft configuration, from single main rotor helicopters to coaxial and tiltrotor aircraft. Rigid-body and inflow states, as well as flexible wing and blade states are used in the analysis. The separate modeling of each rotorcraft component allows for structural flexibility to be included, which is important when modeling large aircraft where structural modes affect the flight dynamics frequency ranges of interest, generally 1 to 20 rad/sec. Details of the formulation of the mathematical model are given, including derivations of structural, aerodynamic, and inertial loads. The linking of the components of the aircraft is developed using an approach similar to multibody analyses by exploiting a tree topology, but without equations of constraints. Assessments of the effects of wing flexibility are given. Flexibility effects are evaluated by looking at the nature of the couplings between rigid-body modes and wing structural modes and vice versa. The effects of various different forms of structural feedback on aircraft dynamics are analyzed. A proportional-integral feedback on the structural acceleration is deemed to be most effective at both improving the damping and reducing the overall excitation of a structural mode. A model following control architecture is then implemented on full order flexible LCTR models. For this aircraft, the four lowest frequency structural modes are below 20 rad/sec, and are thus needed for control law development and analysis. The impact of structural feedback on both Attitude-Command, Attitude-Hold (ACAH) and Translational Rate Command (TRC) response types are investigated. A rigid aircraft model has optimistic performance characteristics, and a control system designed for a rigid aircraft could potentially destabilize a flexible one. The various control systems are flown in a fixed-base simulator. Pilot inputs and aircraft performance are recorded and analyzed. en_US dc.language.iso en en_US dc.title Flight Dynamics Simulation Modeling and Control of a Large Flexible Tiltrotor Aircraft en_US dc.type Dissertation en_US dc.contributor.publisher Digital Repository at the University of Maryland en_US dc.contributor.publisher University of Maryland (College Park, Md.) en_US dc.contributor.department Aerospace Engineering en_US dc.subject.pqcontrolled Aerospace engineering en_US dc.subject.pquncontrolled control en_US dc.subject.pquncontrolled dynamics en_US dc.subject.pquncontrolled flexible en_US dc.subject.pquncontrolled multi-body en_US dc.subject.pquncontrolled simulation en_US dc.subject.pquncontrolled tiltrotor en_US
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