Question of the year, involves a plane, a conveyer belt, and a thought experiment.

[WayneSugar]

A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

Discuss. No Googling.

[rog211]

no it cannot.
here is why:
The design of a plane's wing is meant to move air over the wing in such a way that creates lower pressure above the wing than below. This is what causes the lift. In order for that to happen the plane must be moving relative to the air. In this case that does not happen. the plane does not move relative to the air so there is no lift and hence the plane cannot take off.

[andydreisch]

This would not allo for the Bernoulli (sp?) pricinple to take effect. Thus, no lift. Thus no take off.

Andy

[sadek]

I hate to be "that guy", but the question itself is flawed.

When a plane begins to move forward, the opposing force that causes the plane to require a lot of energy consumption to move forward is the friction due to the opposing airflow. Otherwise, the only force the plane has to work against is the friction of the wheels on the ground, which is designed to be extremely low.

So, could we even create a conveyor that would be able to spin fast enough to hold the plane steady? No way. The power that the jet engines have is far to great to be able to stay still on that conveyor. It would very quickly begin moving forward and take off.

However, if we not considering this a factor, and assuming this is possible, then no, the plane would not be able to take off because there is no airflow to give it the lift.

Thanks

[majed]

Unless we are changing how planes work it will still take off. The reason is that the wheels on a plane freely rotate and do not work like the wheels on a car. There are no gears involved. The plane moves by thrust. So turn on the turbines and lets just say the plane has a thrust of 10 mph. The conveyor belt says ok the thrust is 10mph lets move in the opposite direction at 10mph. The wheels then say ok the conveyor belt wants me to go 10mph and the plane wants me to go 10mph so I am going 20 mph and the plane takes off. Unless we are talking about a hypothetical conveyor belt and a hypothetical plane that doesn't work anything like the real world.

[andydreisch]

How are the security checkpoint lines in this hypothetical world?

Andy

[majed]

Of course in this hypothetical world the plane is already floating since my hypothetical world has no gravity

[andydreisch]

Should we call this thread "Wayne's World"?

Andy

[sadek]

Should we call this thread "Wayne's World"?

I think we should call it "Look what Wayne started"

[WayneSugar]

Imagine this analogy:

You're on a treadmill, in rollerblades. Attached to the wall immediately in front of you is a rope that you have a hold of. You'll eventually be able to pull yourself along the rope and overcome the treadmill.

Therefore the plane will be able to take off.