in the present paper, the aeroelastic stability of helicopter rotor blade is determined using aeroelastic frequency response function. the aeroelastic model of blade is obtained by combining dowell - hodges beam model with loewy unsteady aerodynamic theory which considers an unsteady wake beneath the rotor. equations are formed and aeroelastic frequency response functions are obtained by invert...

In the present paper, the aeroelastic stability of helicopter rotor blade is determined using Aeroelastic Frequency Response Function. The conventional methods of aeroelastic stability usually use an iterative procedure while the present method does not require such approach. Aeroelastic Frequency Response Functions are obtained by inverting dynamic stiffness matrix of the aeroelastic system. S...

System identification methods for non-linear aeroelastic systems could find uses in many aeroelastic applications such as validating finite element models and tracking the stability of aircraft during flight flutter testing. The effectiveness of existing non-linear system identification techniques is limited by various factors such as the complexity of the system under investigation and the typ...

This paper numerically investigates the effect of chordwise flexibility on the dynamic stability of compliant airfoils. A classical two-dimensional aeroelastic model is expanded with an additional degree of freedom to capture time-varying camber deformations, defined by a parabolic bending profile of the mean aerodynamic chord. Aerodynamic forces are obtained from unsteady thin airfoil theory a...

The hypersonic aeroelastic and aerothermoelastic problem of a double-wedge airfoil typical cross-section is studied using three different unsteady aerodynamic loads: (1) third-order piston theory, (2) Euler aerodynamics, and (3) Navier-Stokes aerodynamics. Computational aeroelastic response results are used to obtain frequency and damping characteristics, and compared with those from piston the...

This paper presents a study on the coupled aeroelastic/flight dynamic stability and gust response of a blendedwing-body aircraft that derives from the U.S. Air Force’s High Lift-Over-Drag Active (HiLDA) wing experimental model. An effective method is used to model very flexible blended-wing-body vehicles based on a low-order aeroelastic formulation that is capable of capturing the important str...

The investigation of aeroelastic/aeroservoelastic stability through flight testing is an essential part of aircraft certification. The stability boundary prediction is especially difficult when the instability is associated with nonlinearities in the dynamics. An approach is presented for the characterization of the nonlinear dynamics by noniterative identification algorithms. Two different blo...

A new design concept in the development of vertical takeoff and landing aircraft with high forward flight speed capability is that of the X-Wing. The X-Wing is a stiff, bearingless helicopter rotor system which can be stopped in flight and the blades used as two forward-swept wings and two aft-swept wings. Because of the unusual configuration in the fixed-wing mode, there is a high potential fo...

This technical note is concerned with aeroelastic flutter problems: the analysis of systems undergoing airspeed-dependent dynamic instability. Existing continuation methods for parametric stability are based on marching along an airspeed parameter until point found - approach which may waste computational effort low-airspeed system behavior, before a located and characterized. Here, we describe...