TonyA wrote:
FWIW You can see the damage to the underside here (larger and better enhanced version of the photo linked earlier):

The photo shows the "Good" side as the impact was on the other side.
PIC means Pilot in Command- or the one who make decisions.
My thought on the impact physics, (Not why it happened but why the collision forces happened in a certain way)-
AD was pulling hard G's- probably trying to avoid a collision AT THAT POINT.
Impact was upwards at an angle from the right in the area of the lower longeron or the strongest part of the structure in that area of the P-51.
Wing leading edge of the AD shreds through the thin skin until the spar contacts the longeron and is severally damaged and under the load imposed by the G's snaps.
Note the wing spar of the AD is probably stronger than the longeron of the P-51 so the failure is a combination of damage and forces imposed by the G's being pulled.
Wing skins between fwd and rear spars pull apart on the bottom surface and all the load on the affected portion of the wing are transferred to the rear spar which fails and snaps allowing the damaged outer wing to break off.
AD rotates into the failed wing twisting it away from further contact with the P-51. (Roll seen on the video)
Reason for my theory is the Aileron that remained full span could not have or barely contacted the P-51 as being much more fragile than the wing it should have broke off if contact was made. I have also seen a photo of the complete wing section sitting with the remains of the P-51. Other than the fracture line of contact and failure, it looks complete like you should be able to bolt it back on. The trailing edge of the tip is bent and a slight ripple in the leading edge part way between the fracture and the tip. I only saw the upper surface so I don't know what the lower surface looked like.
In essence IMO it was a perfect combination of placement of the contact areas, high loading of the AD and structure that failed in a certain way that allowed the P-51 to fly on and not lose it's tail all together.
The pilots transcript speaks of wanting to belly in a field but the nose dropped and he was unable to raise the nose so he abandoned the A/C. This follows the Video.
One other item is the video that shows the stability of an aircraft as the P-51 righted itself after the upset. More physics in action.