Integrated Flight Mechanics and Aeroelastic Modelling and Control of a Flexible Aircraft Considering

In this paper, the influence of gusts on the dynamics of a large flexible aircraft is analyzed, and an integrated flight and aeroelastic control law that reduces gust sensitivity is presented. The calculations are based on an integrated model that includes all lSf order couplings between flight mechanic and structural degrees of freedom. Uniform, l-dimensional and multidimensional gust models are imple-mented and used for gust sensitivity analysis. For the exam-ple aircraft, the differences in gust sensitivity calculated with the l-dimensional and multi-dimensional gust models are significant. Integrated attitude, stability augmentation, and aeroelastic control laws for longitudinal and lateral motion are designed using p- synthesis. With the control laws, flight maneuvers do not excite elastic reactions, and the sensitivity to gusts is considerably reduced. Nomenclature Bhh = modal damping matrix k = reduced frequency Khh = modal stiffness matrix L = characteristic wave length for gust (2500 ft) Mhh = modal mass matrix ph = modal applied aerodynamic forces (gust) QW = modal aerodynamic force coefficient matrix tabulated for reduced frequencies k 9 = state vector in generalized coordinates 3 = x location of aerodynamic panel X0 = reference value for aerodynamic coordinate system Kv,W = longitudinal, lateral and vertical velocity par = roll, pitch and yaw rate W = aerodynamic downwash a,P,r = angle of attack, sideslip angle and flight path angle Y = dihedral angle Q = mode shape matrix $,8,w = roll attitude, pitch attitude and heading cp = phase angle cp = matrix of one dimensional spectrum function Y = matrix of two dimensional spectrum function csi,&, = symmetric and antimetric deflection of &ii,&to inner and outer ailerons 5,q,c = aileron, elevator and rudder deflection w = frequency R = ON wave number