
you're describing a scenario where you aren't simply doing a loop de loop, but instead you're using the supermaneuverability of your aircraft to push a flip largely independent of your previous momentum
once your angle of attack is at about 90 degrees, the aircraft's center of drag starts interfering beyond the control of thrust vectoring
1 of 3 things would happen:
your aircraft immediately aims the nose towards the angle you're moving at, likely resulting in a cobra
your aircraft immediately begins aiming the nose towards the angle you're moving at, but enters a spin
your aircraft's wings and horizontal stabilizers cannot resist the stress placed on the airframe, and they break off