In article , Paul Tomblin
wrote:

As for what they're capable of, remember Tex Johnson(sp?) barrel rolled
the 707 prototype (the "Dash-80"). If you don't care if the plane is
usable again after the maneuver, I'm sure you could do a lot more abrupt
maneuvers than that.

Not necessarily... +1-G is +1-G.
The airplane doesn't know what attitude it's in as long as the proper
g-loading is maintained throughout the maneuver. The only variable is
the pilot's level of skill.