Airplane on a Conveyor Belt...

[FLOOB]

Iron let me ask you this, if the takeoff speed of the aircraft is 100mph, and the conveyor belt is moving 120mph, will the plane takeoff?

[NatCigg]

Think of the pulling the table cloth trick.  Here's a test will a plane on a conveyor move at all?    you know, if a plane does not have the thrust to overcome being at rest it is not going to take off on a conveyor 

[AKIron]

The original question (not as posted here) was probably intended as a more simple debate aimed at those who can't distinguish between plane and car wheels. Obviously a conveyor belt that spins only to a hundred miles an hour isn't going to prevent most planes from taking off. The debate became more about physics and inertia when the question of what speed is being matched was raised. Newton's first law comes into play then. A wheel not spinning tends to stay not spinning. Of course you can counter any thrust of the engine if you are allowed to apply any belt acceleration in opposition to the wheels. If you don't get this then you don't understand the forces involved.

[AKIron]

Iron let me ask you this, if the takeoff speed of the aircraft is 100mph, and the conveyor belt is moving 120mph, will the plane takeoff?

Of course it will. See my last post.

[Shuffler]

Think of it like this. A jetliner about to touch down is like a throttled down plane sitting on a conveyor belt. The belt has yet to spin. As soon as the tires touch down it's like the belt just spun up to 130mph. The wheels/tires have an inertia that resists being spun up. While they are skidding force is definitely being applied in the direction opposite that of thrust. The amount of force is relative to the acceleration of belt of the speed of the plane when it touches down. Imagine that force if the plane touched down at 500mph?

Remember, no brakes applied, why do the tires skid?

That is because it is instantaneous. It does not stop the plane and the plane cane take right off.

A conveyor belt is not going to spin up near that fast. Also understand that any loads that cause destruction of the belt as well as the tires. And both the plane and the belt have bearing.

[FLOOB]

Of course it will. See my last post.

Congrats and welcome to the correct side of the argument.

[FLOOB]

Think of the pulling the table cloth trick.  Here's a test will a plane on a conveyor move at all?    you know, if a plane does not have the thrust to overcome being at rest it is not going to take off on a conveyor 

You just said that if a plane isn't able to move then it's not going to be able to move..

Here's your sign.

Maybe it's not what you meant to say, but it's what you said.

[AKIron]

That may be the question as you understand it but it was not the question as it was originally asked here.

Will a plane take off if the belt is spinning at 10,000 miles per hour?

[AKIron]

The original question, if I recall correctly, was if the belt matched the speed of the wheels. I couldn't find the original thread so not sure on that. The question then became what does that mean, the wheels? Are we talking the theoretical center of the axle which would then be the same as the fuselage or are we talking the rotational velocity of the wheels? The asker then stated he intentional left that ambiguous to spur debate, if I recall correctly.

[FLOOB]

 a little way down this forum is a link to the real question!

 read this more than once and hopefully you will understand the plane does not have to stay stationary and the belt is not compinsating for movement of the plane it is only going 100 knots in the oposite direction hence wheel speed 200 knots! plane speed 100 knots!

[NatCigg]

You just said that if a plane isn't able to move then it's not going to be able to move..

Here's your sign.

Maybe it's not what you meant to say, but it's what you said.

right, if a plane cant move then it cant take off on a conveyor. I also implied that it is very plausible that a plane on a conveyor could sit in one spot despite being on a moving conveyor. 

[Reaper90]

right, if a plane cant move then it cant take off on a conveyor.

Why would it not be able to move? Is it tied down?

[Bizman]

right, if a plane cant move then it cant take off on a conveyor. I also implied that it is very plausible that a plane on a conveyor could sit in one spot despite being on a moving conveyor. 

Why wouldn't the plane move? If I put a freewheeling plane on a belt sander and pull a string attached to the nose, the plane would move. Propellers or jet engines equal the string, they have nothing to do with the ground below. If they had, no plane could ever fly.

[Shuffler]

Why wouldn't the plane move? If I put a freewheeling plane on a belt sander and pull a string attached to the nose, the plane would move. Propellers or jet engines equal the string, they have nothing to do with the ground below. If they had, no plane could ever fly.

For such a simple thing folks who are generally intelligent just lose it. LOL

[AKIron]

For those who see no counter force to thrust being applied by the belt answer whether the speed of the belt makes any difference?