When I was stationed at a squadron (VT-10) in the hangar next to the Blue Angel's we used to come running outside to watch Fat Albert take off (their cargo plane). Neatest thing to watch this big heavy motherfucker take off vertical using just a small patch of runway.
With
rockets, tonks. a JATO assisted takeoff is a rocket takeoff, not an airplane takeoff. You're right though, it's pretty impressive. I think that's outside the parameters of this thought experiment though.
Another note, tonks. The engines of most jet or prop planes are not designed to generate any lift at all. In fact, they're rather carefully designed to send all their thrust forward through the center of mass of the airplane.
Unc, your buffer lift idea has merit but I think if it would work at all, it'd only work on a light plane. There really isn't enough data on the treadmill parameters to even make a guess how much of how much buffer lift would be available but I think it unlikely to be several tons. I know that a 747 needs over 360kph of airspeed to lift off. If the treadmill is matching that speed in the opposite direction, I think you'd find that any buffer lift generated by the speed of the treadmill whizzing by would be insignificant. The answer to the question is still no, IMO.
K62s example points it out rather nicely. On an aircraft carrier, they turn into the wind and then shoot the plane off the ship with a
very powerful catapult. This is because airplanes need speed
through the air to fly. The treadmill experiment is designed specifically to eliminate that.