think about this...

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If the plane is not moving, no air is being forced under its wings. If no air is being forced under its wings, there is no lift. So it stays grounded.

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When did I say the plane wasn't moving?

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you essentially gave us two velocity vectors of equal magnitude that work in exactly opposite directions. the plane has zero velocity relative to somebody standing on the ground observing it. it is going nowhere.


i think.

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Everyone seems to be figuring this from the standpoint that the plane's wheels are where the thrust is comming from. The wheels do not push the plane forward, the props do.

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Why is that relevant? The thrust from the props = X. The "thrust" from the moving conveyor-runway = -X. The aircraft is not moving relative to the air. Hence, no airspeed, so no lift.

[Eurotrash]

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Everyone seems to be figuring this from the standpoint that the plane's wheels are where the thrust is comming from. The wheels do not push the plane forward, the props do.

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no. I understand what causes the plane to move forward.

[FouTight]

The problem with this scenario is that the drive isn't created by the wheels, so this belt wouldn't result in the plane not moving, it would mean the wheels would be moving REALLY quickly, but the thrust would still push teh plane forward.

This scenario is impossible.

[fnord_too]

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The problem with this scenario is that the drive isn't created by the wheels, so this belt wouldn't result in the plane not moving, it would mean the wheels would be moving REALLY quickly, but the thrust would still push teh plane forward.

This scenario is impossible.

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Yeah, the exact speed I think will be determined by the friction in the axels given that the wheels are not skidding in any way. It's hard to picture the forces in my head on this one, so I am not sure if there can even be any force acting on the plane to counter the force of the thrust, but I don't know that it is impossible. I was assuming it was possible since I was reading it as a given.

[Slow Play Ray]

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The problem with this scenario is that the drive isn't created by the wheels, so this belt wouldn't result in the plane not moving, it would mean the wheels would be moving REALLY quickly, but the thrust would still push teh plane forward.

This scenario is impossible.

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Yeah, the exact speed I think will be determined by the friction in the axels given that the wheels are not skidding in any way.

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I was thinking about this earlier, too. I think the wheel speed/conveyor speed would basically accelerate exponentially until the plane took off. Clearly this whole scenario is probably not physically possible, but it's an interesting theory to discuss.

[tolbiny]

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The problem with this scenario is that the drive isn't created by the wheels, so this belt wouldn't result in the plane not moving, it would mean the wheels would be moving REALLY quickly, but the thrust would still push teh plane forward.

This scenario is impossible.

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Yeah, the exact speed I think will be determined by the friction in the axels given that the wheels are not skidding in any way.

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I was thinking about this earlier, too. I think the wheel speed/conveyor speed would basically accelerate exponentially until the plane took off. Clearly this whole scenario is probably not physically possible, but it's an interesting theory to discuss.

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Wait- How much money do we have in the crimson challenge fund? Lets give it a go!!!

[stigmata]

[fnord_too]

If a plane (specifically its wings) is traveling with zero speed with respect to the air, then there can be no lift. If the props are forcing air over the wings, there can be lift (though then the plane is not traveling with zero speed wrt the air, so we don't contradict the above). If you have some VTOL capabilities (really just VT) you could take off. I think in the scenario you described, you cannot, though I am not sure how much air the props push over the wings.

The discussion in this thread makes me think perhaps your phrasing is awkward.

[FouTight]

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The discussion in this thread makes me think perhaps your phrasing is awkward.

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I agree with this, the OP is a bit convoluted, but everyone is seeing this as some sort of runnign on a treadmill scenario, when it really isn't.

[CrazyEyez]

This scenario is no different than if there was no conveyor runway but instead the breaks were locked on or the wheels were blocked. Sure there is some lift but not enough to take off.