Non-linear stability analysis of aircraft at high angles of attack

The stability of an aircraft at high angles of attack is considered. Explicit results for the bifurcating paths and their stability are obtained for values of the system parameter in the neighbourhood of its critical value. It is shown that both Hopf as well as degenerate Hopf bifurcation could take place depending on the type of bifurcation parameter chosen. However, in the degenerate case there will be two periodic bifurcating paths with two different frequencies, which are either both stable or both unstable. For supersonic double-wedge air foil, the bifurcating path is numerically evaluated in the case of degenerate Hopf bifurcation.