F-15B High Angle-of-Attack Phenomena and Spin Prediction Using Bifurcation Analysis.

摘要

Modern fighter aircraft are being designed to be operated at higher and higher angles-of-attack. The resulting increase in maneuverability is offset however by an increase in susceptibility to departure from controlled flight. An investigation of the F-15B fighter aircraft was undertaken to predict high angle-of-attack phenomena such as flat spins. Aerodynamic forces and moments as a function of control surface deflections were modeled over a wide angle-of-attack range (-20 deg < or = alpha < or = +90 deg) and were then used to formulate a non-linear eight state (alpha, beta, p, q, r, Theta, Psi, V) aircraft model. Equilibrium and periodic solutions to the resulting equations of motion were then computed using a bifurcation analysis package. A number of bifurcation points, limit points and Hopf bifurcation points were detected indicating changes in flight stability. Several stable equilibrium solution branches at angles-of-attack greater than 70 degrees were observed which correspond to flat spin behavior. Theoretically predicted flat spin conditions correlated well with empirical flight test data. In addition stable equilibrium and periodic surveyed resulting in a global map of stability as a function of control surface deflection for the F-15B. Theses. (jhd)