As they say (at least where I am :), "it's easy being a general after the battle", but I don't see much aerodynamically troublesome in this matter.
What's the problem with "one wing" (more properly, half-wing) shot off? To maintain level flight, first, the other wing has to give twice as much lift, and second, the rolling moment around the CG would have to balance out. Nothing more than that. Here is how it aerodynamically goes.
Half of the wing perishes. The sudden lack of equal and opposite balance to the rolling moment produced by the remaining wing half, make airplane start spinning. The pilot instinctively moves the stick so to counter roll, which does the right thing in this case too: raises the outboard aileron (quite powerfull on F-15) on the remaining half of the wing, and possibly counter-turning intact horizontal tailplanes (all-movable on F-15).
However, this is still not enough to balance out the rolling moment produced by the assymetric wing lift. The controls are maxed out, so the pilot cannot any longer increase counter roll moment, at the same velocity. So he speeds up (afterburner), which increases the counter moment, but also increases the moment due to lift (both roughly proportional to square of velocity). However, the pilot can now reduce the lift without reducing the counter-roll moment, by keeping controls maxed out and reducing wing's angle of attack. The airplane comes to a balance. (Any yawing motion introduced by the assymetric drag can easily be balanced by twin vertical tails, also intact.)
Unfortunately, the airplane is now quite unaerodynamic: a lot of drag due to wing rubble and control deflection, much less lift than normal. Basically, the lift is now produced only by the body and, looking at F-15's wing, roughly half of the intact wing half -- the outboard part where the aileron is raised produces downward force to counterbalance roll. So, it needs much higher speed for this little lifting performance to be enough to balance the weight. And that's precisely what the pilot says, they were landing at twice the normal landing speed. This means that the aerodynamics was spoiled so that the produced lift was only, say, one quarter to one sixth (assuming rough landing :) of the normal. This sounds quite plausible.
Now, unlike a conventional airplane configuration (general aviation, transport, airliners...), F-15-like fighters have quite stubby wings, lifting body, very high-power flight controls, and ample thrust reserve. So it had at least enough authority to conduct all the described steps, which a normal airplane would not.
On the other hand, the dynamics of transition from spinning to level flight and flight control coordination afterwards, must have been hideous (though, I'm not controls person). Perhaps this feat is more of a testament to F-15's flight control system and/or pilot's skill? I mean, aside from the fact that they actually didn't eject -- I really sometimes don't understand this thing between the pilot and the airplane :)
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Chusslove Illich (Часлав Илић)
