Global Stability and Control Analysis of Aircraft at High Angles-of-Attack.
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Abstract : High angle-of-attack phenomena have been of interest to aerodynamicists, aircraft designers, pilots and control system analysts ever since the advent of modern high performance aircraft. Due to the concentration of inertia along the fuselage, the modern jet fighters are highly susceptible to poststall departures and spin. In spite of extensive design effort, modern aircraft still inadvertently enter spins which sometimes result in loss of life and/or property. Extensive wind-tunnel testing and radio-controlled flight testing has been done over the last 20 years to gain a better understanding of the dynamic instabilities at high angles-of-attack. A basic problem has existed in interpreting these data and in making predictions of aircraft dynamic behavior so as to achieve close agreement with flight test data. Most of the work on this project involved a study of the second aircraft model, the F-4. A detailed description of modeling this aircraft, correlation time history runs, and a high angle-of-attack analysis utilizing equilibrium and bifurcation surfaces, is included in this report. The equilibrium spin regimes were found to be rather insensitive to aerosurface control deflections, a result consistent with observed performance. Studies were conducted as well in the stall/post-stall/spin entry regime, a control synthesis approach was initiated, and thrust effects were analyzed.