I routinely get my VStab blown off! 
. Well in that case, we would be forced to use ailerons to counteract engine torque. But since ailerons naturally produce some yaw rate, the aircraft would rapidly acquire a large horizontal AoA. This is assuming the aircraft is geometrically symmetric along the plane defined by the VStab. If not, any asymmetries would be enhanced and would probably also contribute to the yaw. The result: a flat spin, with some rolling motion due to torque. I think that agrees pretty well with combat experience in AH.
I agree. However, my recollection of aircraft performance said there is a significant stability drivative that we dubbed "the weathervane effect". It effectively minimizes your sideslip. While the vertstab is doubtless a big contributor to that effect, I am also very sure that on a/c of the type we fly, the aft fuselage is also a significant contributor.
I just wonder if, given some trace of d(Yaw moment, call it Z)/d(yaw angle, call it phi) and the fact that at some phi we'd have a yaw contribution from that effect that was proportional to that coeff and to the square of velocity that the flat spin you posit might be a major issue at low speed but much, much less of a problem if we've got a little smash-ola? It's hard to say because the induced drag diff due to ailerons left to right will also be higher.
I'd further posit that a relatively slab-sided bird like the 51 would have a steeper slope/higher Cz w/r phi at all phi than something with a rounder/narrower rear fuselage like a d-9.
I was also considering the case where we're sharply banked at the time of the separation event. This looks like a decent analog to out horistab discusion only there's less possible lift forward - just the fuselage contribution and whatever vertical component the wings are producing. Clearly here, we'd be negative cambered on the vertstab to try to keep the nose up and at a very high Cl ergo alpha on the wings to attempt to keep from losing lots of alt. Blow the vertstab off and do we now also yaw nose up? I think it likely - especially given the attenuated nose-down pitch moment of the wings in that plane (horizontal w/r ground).
One other thought - with the canard, if we blow the horistab off it seems to me the center of lift would shift further aft. That looks like it might pitch nose down - a safer failure mode.
Anyway, that's my thought on this "Mirrors" issue. Best to keep 'em on the airplane because strange things can happen when they get shot off.
