Airplane on a Conveyor Belt - Exclusive Photos!

You and I and others may have a firm grasp on the physics involved, but you'd be surprised how many people don't seem to get it.

If you interpret the question as "If the plane doesn't move, can it take off?" then no, the plane can't take off.

If you interpret the question as "Can a conveyor keep a plane from moving?" then yes, the plane can take off.

I'm continuously surprised by people showing up to debate the latter interpretation.

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"Aaaahhh!

I didn't see your proposed experiment until now and I agree; under most of these open-ended conditions, flight is possible.

There are a few propositions under these terms, however, that, as a matter of fairness, should be considered:

If the plane is capable of infinite thrust and the conveyer is limited to a set maximum, then the plane will always get airborne and the myth is true.

If the plane has unlimited thrust potential and the conveyer also has infinite potential, then the myth is plausible but impossible to research.

If the plane has limited thrust and the conveyer is also limited on potential, then the myth is both plausible and possible to research. It really comes down to how much bigger one item is over the other and your hypothesis hints that I'm allowed to get a bigger, more powerful conveyer.

If the plane has a set limit on thrust and the conveyer has infinite potential, then the plane will never fly. Eventually, the wheels will be unable ward off all of the drag force and the myth is busted.

Under these sets of values, You're right at one end of the scale and I'm right at the other.

If we're talking abount an all-or-nothing proposition where plausible is not an acceptable outcome, then, under the Scientific Method of Investigation, the myth must be busted because one set of variables exist that negate the hypothesis.

Either way, I appreciate the friendly sparring. My hats off to a worthy opponent!"

The problem I have with your argument is in the application of the force exerted by the conveyor onto the plane. The conveyor might be powerful enough to move tons of steel, but if there's not enough friction between it and the plane, that force will never effect the plane. Because the wheels of the plane are free-spinning, almost all of the friction is removed, and so the plane never feels the force of the conveyor. The only impact is that the plane's wheel spin faster.

Back to the experiment.

Take any real-world fixed-wing aircraft that you might see in operation at a civilian airport. This excludes helicopters and military aircraft, such as the Harrier or any other that might have VTOL capability.

Take any real-world conveyor or treadmill, with a belt of sufficient length and width to fully support the chosen plane. If you feel that its drive motor is inadequate, feel free to replace it with the most powerful drive motor in the world.

Perform the experiment as I described it. Measure the thrust generated by the plane with the conveyor off, then measure the force exerted on the plane by the conveyor with the plane off. Use maximum speed or power settings for both.

I *guarantee* you that the thrust will be greater than the drag.

Looking back at your argument one more time, you are stipulating that the plane is not allowed to generate more thrust than the conveyor is exerting on it. This constraint is not what is required by the myth, as the myth specifies matching speeds, not matching forces. What you are saying is that the plane isn't allowed to apply full power, and thus *try* to take off.

I do admit that if the conveyor moves fast enough, there is risk of damage to the tires and wheels, which could severely impact the plane's ability to take off, much less land again (should it manage to survive long enough). But since the speeds should be matched, I suspect the plane would be airborne by then.

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