NATO STO

The process of substantiating the aeroelastic stability of modern aircraft requires a combination of numerical and empirical analysis. The ground and flight testing required to collect the empirical data is arduous at best and extremely hazardous at worst. There are a number of phenomenon that fall into the area of aeroelasticity. The most notable of which is flutter. Limit Cycle Oscillation is a non-linear form of flutter in which a nonlinearity, either in the structure or the aerodynamics, limits the amplitude of the oscillation. Divergence is similar to flutter except that it is non-oscillatory. Control reversal occurs when the force from the deflection of a control surface, normally the aileron, causes the wing to twist in the opposite direction to the point that the control surface and wing twist net effect is in the opposite direction intended by the pilot. Aerodynamic buzz is the vibration of a control surface due to unsteady aerodynamics and/or unsteady shock waves on the control surface. Buffet is a shaking or shuddering of the aircraft structure caused by separated flow or vortex shedding. These phenomenon have impacted all NATO nations conducting flight operations, particularly with varying aircraft store configurations.