Plane on a treadmill

[Conundrum 1]

**I searched for this and found nothing, so forgive me if it was deleted or something**

A plane is standing on a runway that can move (like a giant conveyor belt). This conveyor has a control system that tracks the plane's speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

Will the plane be able to take off?

[leroydb 0]

is there any ground wind? direction?

Leroy


..I knew I was an unwanted baby when I saw my bath toys were a toaster and a radio...

[mnealtx 0]

Nope...no air movement over the wing - no flight.

And yes, it's a repost, but I don't recall the thread it was in.

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[Conundrum 1]

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is there any ground wind? direction?

It's irrelevant. For argument's sake, we'll say the wind is calm.

[Conundrum 1]

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Nope...no air movement over the wing - no flight.

And yes, it's a repost, but I don't recall the thread it was in.

Why do you think there will be no air movement over the wing?

[sundevil777 102]

Yes, it will take off, with the wheels of the plane rotating faster than normal. The conveyor cannot, and is not defined as being able to keep the plane stationary relative to the ground, so the only result is the wheels rotating faster.

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2006172#2006172

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[DJL 235]

If the plane is a Harrier, yes.

Edit: Thought about is a second longer. Nope, doesn't matter. Plane will take off.

"I encourage all awesome dangerous behavior." - Jeffro Fincher

[leroydb 0]

yea, hum... where are the engines? will there be enough air movement from the engines to get it off the ground?

But one must question If it is possible, might it have already been tried or accomplished?

Leroy


..I knew I was an unwanted baby when I saw my bath toys were a toaster and a radio...

[Conundrum 1]

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If the plane is a Harrier, yes.

Why's that?

[mnealtx 0]

Because there will no movement of the wing relative to the air mass. The wheels can spin as fast as they want to, but if there's no airflow over the wing, there's no lift.

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[jakee 1,584]

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A plane is standing on a runway that can move (like a giant conveyor belt). This conveyor has a control system that tracks the plane's speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

I have yet to see a plane that is driven by its wheels.

Do you want to have an ideagasm?

[Conundrum 1]

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Because there will no movement of the wing relative to the air mass. The wheels can spin as fast as they want to, but if there's no airflow over the wing, there's no lift.

That is incorrect. The plane will be moving forward creating airflow over the wings.

[justinb138 0]

It will be moving forward in relation to the surface (or the surface will be moving backward in relation to the plane), but not relative to the air, which provides the lift needed for it to fly, so it will not take off.

[Icon134 0]

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Yes, it will take off, with the wheels of the plane rotating faster than normal. The conveyor cannot, and is not defined as being able to keep the plane stationary relative to the ground, so the only result is the wheels rotating faster.

What he said... An airplane isn't driven by its wheels but by its props... (the wheels are able to rotate freely...)

Livin' on the Edge... sleeping with my rigger's wife...

[sundevil777 102]

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Because there will no movement of the wing relative to the air mass. The wheels can spin as fast as they want to, but if there's no airflow over the wing, there's no lift.

Wrong. The wheels will spin twice as fast, that is the only difference.

Think of it this way, if the wheels had zero friction and rotational inertia, the plane would not move at all relative to the ground, no matter how fast you made the conveyor move. There is actually some friction/inertia, but it would be a minor factor.

There is nothing in the scenario that says the plane can't move relative to the ground, just that the conveyor speeds up as the plane moves relative to the ground, hence the wheels spin at twice the speed. In fact, if the plane can't move relative to the ground, then the conveyor won't move either.

There is a lot more on this in the old thread, no need to rehash it.

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2006172#2006172

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[stitch 0]

Harrier is a VTOL fixed wing fighter.Meaning it takes off and lands like a helicopter.

"No cookies for you"- GFD
"I don't think I like the sound of that" ~ MB65
Don't be a "Racer Hater"

[Remster 30]

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Because there will no movement of the wing relative to the air mass. The wheels can spin as fast as they want to, but if there's no airflow over the wing, there's no lift.

That is incorrect. The plane will be moving forward creating airflow over the wings.

Well, since we're talking pure theory without a actual practical application: IMO thats not correct.

The rollng of the wheels on the threadmill will create a very small backwards force due to the rolling resistance of the wheels. If the threadmill is going fast enough, that force could in theory create a counterforce equal to the thrust of the engine. (in practice, the wheels and bearings would probably burst in flames from the speed tho lol)

Remster

[mnealtx 0]

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Because there will no movement of the wing relative to the air mass. The wheels can spin as fast as they want to, but if there's no airflow over the wing, there's no lift.

That is incorrect. The plane will be moving forward creating airflow over the wings.

Nope - the conveyor belt is keeping the plane from moving forward relative to an observer to the side, therefore no movement relative to the air mass. No movement, no lift.

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[Conundrum 1]

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Harrier is a VTOL fixed wing fighter.Meaning it takes off and lands like a helicopter.

No kidding. Regardless if it was a Harrier or not, it would still take off.

[Remster 30]

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Think of it this way, if the wheels had zero friction and rotational inertia,

Thats the problem tho. They have friction, both rolling resistance, and bearing friction.

But, I'm cutting hairs in 4 here

Remster

[Conundrum 1]

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Because there will no movement of the wing relative to the air mass. The wheels can spin as fast as they want to, but if there's no airflow over the wing, there's no lift.

That is incorrect. The plane will be moving forward creating airflow over the wings.

Well, since we're talking pure theory without a actual practical application: IMO thats not correct.

The rollng of the wheels on the threadmill will create a very small backwards force due to the rolling resistance of the wheels. If the threadmill is going fast enough, that force could in theory create a counterforce equal to the thrust of the engine. (in practice, the wheels and bearings would probably burst in flames from the speed tho lol)

The wheels would not create enough drag to overcome the thrust of the engine.

[Remster 30]

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The wheels would not create enough drag to overcome the thrust of the engine.

Make the threadmill go fast enough, and the wheels will lock from the fire!

Remster

[Conundrum 1]

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Because there will no movement of the wing relative to the air mass. The wheels can spin as fast as they want to, but if there's no airflow over the wing, there's no lift.

That is incorrect. The plane will be moving forward creating airflow over the wings.

Nope - the conveyor belt is keeping the plane from moving forward relative to an observer to the side, therefore no movement relative to the air mass. No movement, no lift.

Why do you think the conveyor belt will keep the plane in one place?

[sundevil777 102]

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Nope - the conveyor belt is keeping the plane from moving forward relative to an observer to the side,

Wrong. The conveyor matches the speed of the airplane relative to the ground, so the wheels rotate twice as fast. If the speed of the plane is 0, the conveyor speed must be 0. If the plane moves forward relative to the ground, then the conveyor moves in the opposite direction at the same speed, thus the wheels rotate twice as fast. Apart from the inertia/frictional effects of the wheels, the take off is normal.

PLEASE READ THE OLD THREAD:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2006172#2006172

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[JohnRich 4]

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If the plane is a Harrier, yes.

Why's that?

The Harrier vectors engine thrust downward and can take off like a rocket, or a hovercraft - it doesn't require aerodynamic lift over the wings.

I'm with mnealtx: the plane, by definition, is stationary relative to the air around it, and therefore has no lift for takeoff. It's just going to be spinning it's wheels in-place like mad, and going nowhere.