The paper examines the instabilities encountered on extreme change in the angle of attack till 90 degrees. The study involves the aerodynamic flow unsteadiness. Unsteady moment coefficients data from un-swept delta wing at low aspect ratio pitching up and down moments are used. A model is developed to represent the dynamic-aerodynamic motion. A seventh order polynomial fit is used to find the fitted  as a function of a for different pitch-up and pitch-down K’s from 0.0 to 0.06 for the 1.5 aspect ratio delta wing. A fifth order polynomial equation is used to find the K variable constants. The results show different and more accurate instability points such as “pitch-up” and “wing-rock”, also more practical numerical results of the post critical behavior.

aerodynamic, low speed, jet aircraft, high angles of attack, flow unsteadiness.