Identification of a High-Order Linear Model of the UH-60M Helicopter Flight Dynamics in Hover

Abstract

*A high-order linear state-space model of the flight dynamics of the UH-60M helicopter in hover is identified from flight-test data. The 28-state linear dynamic model includes the six rigid body degrees of freedom, first-order rigid-blade longitudinal and lateral tip path plane (TPP) flapping, second-order rigid-blade coning dynamics, first-order vertical inflow, main rotor angular velocity, and rigid-blade TPP regressing lead-lag dynamics. The model structure also includes dynamic states for the primary servo actuators and a kinematic model of the UH-60 control mixer and swashplate control linkages. This model structure provides a convenient interface at which the model can be partitioned for application to flight-control system design for the UH-60M Upgrade aircraft, which will include a highbandwidth fly-by-wire flight-control system and will replace much of the mechanical control system on the baseline UH-60M. The identified model is of sufficient accuracy and order to be used with confidence in the design and analysis of high-bandwidth fly-by-wire flightcontrol laws for the UH-60M Upgrade helicopter in the hover and low-speed flight regimes.