Would a plane take off on a tredmill?

[The G-Man]

the airplane would not have any velocity. But the wheels would ahve plenty of speed. Airplane just wastes fuel on keeping up with treadmill, end of story.

Last year we had a HUGE discussion over this on another forum.

[owequitit]

the airplane would not have any velocity. But the wheels would ahve plenty of speed. Airplane just wastes fuel on keeping up with treadmill, end of story.

Last year we had a HUGE discussion over this on another forum.

I am assuming you may be referring to Accordinglydone.

The ones that said it can't fly are wrong.

I will bet you $1,000,000 U.S. dollars that if I put a rubber bad airplane on a treadmill that is moving in the opposite direction as fast as it can go, and I release that rubber band airplane from a standing stop that it will:

1) move in the direction opposite the treadmill

2) take off

3) fly away

Did you bother to read the article I posted?

The treadmill and the wheels have nothing to do with the airplane accelerating. The treadmill and the wheels have no way to stop the airplane from accelerating, and the airplane doesn't care what the wheels are doing. They are used only for support on the ground while it isn't flying. They put wheels because it allows them to roll it around.

The airplane is concerned with 1 thing and 1 thing only. The speed of the air over its wings. If the necessary takeoff speed is reached at 100MPH, then the treadmill will be going backwards at 100MPH, but the wheels will be moving at 200MPH, but the airplane will still be moving FORWARD at 100MPH.

Even if the treadmill is matched to the speed of the wheels, the treadmill will continue to accelerate backwards at infinite speed until the airplane reaches takeoff speed and then takes off.

The wheels, the treadmill, and what they are doing is 100% irrelevant to the flight of the airplane.

The airplane does not get its forward velocity or its lift from the wheels. It gets its forward velocity from the thrust of A) the propeller or B) the reaction of the jet exhaust against the atmosphere. It gets its lift by the air flowing over the wing. As long as the thrust is thrusting and the lift is lifting, it WILL fly.

[Accord R33]

wait a min. i was under the impression that this ment the airplane was completely stationairy. I understand that the thrust from the engines would make it move forward no matter what the wheels were doing.

If the myth allows for the plane to have a velocity, than of course it will take off

[The G-Man]

In the heated discussion we had a twistedforums.com, we assumed that the treadmill always was able to match the speed of the wheels, not allowing the airplane to gain velocity.

[Accord R33]

In the heated discussion we had a twistedforums.com, we assumed that the treadmill always was able to match the speed of the wheels, not allowing the airplane to gain velocity.

right, but the thrust from the engine would propell the plane forward. the wheels of an airplane simply roll as far as i know. they are not powered.

For some reason i thought the myth ment that there was a "theoritical" threadmill that was able to keep the plane stationary

[The G-Man]

You all are getting it wrong, which is taking me back to the arguments I had 1 year ago.

IF; you had an airplane that was held stationary on a giant treadmill, the wheels would simply roll in place and the airplane would be still.

IF; you had an airplane on a giant treadmill, that was not holding the plane back, and the airplane did NOT have engines on the airplane would simply move in the direction of the treadmill.

IF; you had an airplane on a treadmill, as described directly above, except with the engines on, and a treadmill that automatically speeds up to match the airplane's speed, the thrust from the jets would simply CANCEL out the treadmill's speed and the airplane would be effectively still.

NOW; if the treadmill had a set speed, at some point the thrust of the jets would overcome this speed and the plane would gain velocity.

[owequitit]

You all are getting it wrong, which is taking me back to the arguments I had 1 year ago.

IF; you had an airplane that was held stationary on a giant treadmill, the wheels would simply roll in place and the airplane would be still.

IF; you had an airplane on a giant treadmill, that was not holding the plane back, and the airplane did NOT have engines on the airplane would simply move in the direction of the treadmill.

IF; you had an airplane on a treadmill, as described directly above, except with the engines on, and a treadmill that automatically speeds up to match the airplane's speed, the thrust from the jets would simply CANCEL out the treadmill's speed and the airplane would be effectively still.

NOW; if the treadmill had a set speed, at some point the thrust of the jets would overcome this speed and the plane would gain velocity.

Bring $1,000,000.

You have a fundamental lack of understanding about how a plane flys, and how all of the elements of this "puzzle" inter-relate.

I your above "facts" are true, then the airplane will move backwards because the treadmill is going faster than the airplane. But it will not. It will instaneously go forward and take off.

If your "facts" are true, how is that possible?

Go buy a rubber band airplane and try it if you don't believe me.

[ACC0RD22]

Yes that would be me!

The airplane WILL takeoff.

The wheels on an airplane have nothing to do with the forward movement of the airplane, nor do they have any way to stop it from moving without touching the brakes. The wheels can be moving backward at 3,000,000 MPH, and the plane will still roll forward.

I will bet $1,000,000 to anyone who doesn't believe me.

Thank you. I really dont understand how this is so hard for people to grasp.

It doesnt matter what the wheels or treadmill are doing. at all. You cannot make the treadmill match the planes velocity, because you are talking about two different speeds, one being air speed, and one being ground speed.

[The G-Man]

I have a fairly good understanding of how a plane works, I have been around the damn things since I was 3 weeks old.

Now, in order for a modern jet to fly, it must have air moving across the wings. The jet underneath these wings does not help the air move over the wings, except when the plane starts to gain forward velocity.

This mythical treadmill is designed to match the speed of the wheels, but of course the wheels will not turn until the pilot moves the throttle, because the plane cannot gain groundspeed without thrust. So as the pilot applies more throttle into the equation, the treadmill will speed up to match the speed of the moving wheels, or the force of the thrust. The plane would not gain groundspeed, thus no air moving over the wings, and no takeoff.

The cheap rubberband plane does not conform to the myth, the treadmill will have a set speed and the plane can overcome that. Also, this is a prop plane, which will be moving the air in front of the plane, or right above the wings, if twin-engine, and will create moving air over the wings.

[The G-Man]

Thank you. I really dont understand how this is so hard for people to grasp.

It doesnt matter what the wheels or treadmill are doing. at all. You cannot make the treadmill match the planes velocity, because you are talking about two different speeds, one being air speed, and one being ground speed.

the plane would not have velocity.

[ACC0RD22]

yes, yes it would. it would outrun the treadmill. since the planes engines work INDEPENDENTLY of the wheels (I.E. they dont matter, it might as well be on stilts) it doesnt matter what surface the plane is on, it will still take off.

[J-specCb4]

who gives a fuck how fast the treadmill is moving or direction as long as the plane produces the proper thrust and lift it will fly

[The G-Man]

Ok, say you had a jet car, its wheels would move independently of the engine. If it was on a treadmill that matched its speed it would not move forward.

And, a plane on stilts would never take off.

[ACCORDianate]

No airflow over the wings means no lift.

x2.

The end.

[owequitit]

I have a fairly good understanding of how a plane works, I have been around the damn things since I was 3 weeks old.

Now, in order for a modern jet to fly, it must have air moving across the wings. The jet underneath these wings does not help the air move over the wings, except when the plane starts to gain forward velocity.

This mythical treadmill is designed to match the speed of the wheels, but of course the wheels will not turn until the pilot moves the throttle, because the plane cannot gain groundspeed without thrust. So as the pilot applies more throttle into the equation, the treadmill will speed up to match the speed of the moving wheels, or the force of the thrust. The plane would not gain groundspeed, thus no air moving over the wings, and no takeoff.

The cheap rubberband plane does not conform to the myth, the treadmill will have a set speed and the plane can overcome that. Also, this is a prop plane, which will be moving the air in front of the plane, or right above the wings, if twin-engine, and will create moving air over the wings.

You might want to go back to physics class.

The wheelsMOVE INDEPENDENTLY OF THE AIRPLANE!!!!!!!!!!!!

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in·de·pen·dent
Function: adjective
1 : not dependent on others (as parents) for livelihood; especially : not a dependent <declared she was independent on her financial aid form>
2 a : not affiliated with another usually larger unit <an independent adjuster> b : not contingent on something else <an independent promise> —in·de·pen·dence noun —in·de·pen·dent·ly adverb
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They can roll backwards at 7,000 miles an hour and the airplane still has the ability to move forward because the wheels are negating nothing.

This is how it would work in real life. I am going to try and find a video camera and a treadmill and I will demonstrate this "impossibility" in real life.

1) The plane is stationary,the treadmill is stationary, the wheels are stationary

2) The pilot applies power, the plane begins rolling forward. The treadmill begins moving backward at the same rate (the question was very specific about stating that the treadmill matched the speed of the plane). The wheels begin turning at twice the rate the other two are moving because they have to match the difference in speed between the two objects.

3) The plane continues to accelerate. We are now at 20 knots (1 knot = 1.15 MPH). The treadmill is moving backwards at 20 knots. The wheels must move at 40 knots to keep up because they have to account for both speeds. Because the wheels roll independently of the airplane, this doesn't matter. It is no different than if the airplane was moving 40 knots over a stationary runway.

4) The plane continues to accelerate, because the thrust of the jet is still reacting against the atmosphere, propelling the aircraft forward. We are now at 100 knots. The treadmill is moving backwards at 100 knots, and the wheels are now turning at 200 knots. Again this makes no difference because it is the same as if the airplane was moving over a stationary runway at 200 knots. All the wheels know is that they are rolling.

5) The thrust is still thrusting, and the plane is still accelerating because the acceleration is dependent on the thrust of the engines and not the rolling of the wheels. We have now accelerated to 150 knots and it is time for lift off. The treadmill is rolling backwards at 150 knots, and the wheels are now rolling at 300 knots! This is exactly the same as if the airplane was rolling over a stationary runway at 300 knots. The jets are still pushing and since the airplane's movement is dependent upon the thrust of the jet, the aircraft is still moving forward.

6) Rotate! The nose of the aircraft begins to lift off, as the nose gear clears the ground, the nose wheels starts to decellerate. Why? Because it is no longer rolling across the runway. BUT WAIT THERE'S MORE! The airplane is still moving at 150 knots, the treadmill is still rolling at 150 knots in the opposite direction, and the main wheels are still rolling at 300 knots because they are still in contact with the treadmill.

7) The nose continues to rise and finally the angle of attack is large enough to create sufficient lift to takeoff. The plane begins to rise, the main wheels come free of the treadmill, and the airplane continues to fly.

Most people think of simple force addition. It used to confuse me too. The problem and the thing that confuses people is that the wheels have absolutely nothing to do with the movement of the airplane.

Their operation is completely independent of what the airplane does.They don't have any effect on the operation of the airplane, which means that any force you apply to them will also have absolutely no effect on the operation of the airplane. Since our treadmill is applying force to the wheels and only the wheels, it affects NOTHING.

Even if the treadmill were setup to match the speed of the wheels, it still affects NOTHING, because the wheels still have no effect on what the airplane is doing. They can't stop it, they can't change it, they are just being pulled along for the ride.

If you were to tie the airplane to a tree and then turn the tread mill on, and the airplane stays where it is because of the rope, have you altered the movement of the airplane? No you have not. The treadmill will go backwards, and the wheels will roll, but the airplane will stay still because of the rope.

The exact same concept works in this example. The thrust and only the thrust is what dictates the movement of the airplane.

Everything else is superfluous. It has nothing to do with anything.

As long as there is thrust pushing the plane forward, IT WILL ACCELERATE, because thrust is what accelerates it.

Period.

Once it begins to accelerate it begins to generate lift, because lift is dependent on airflow over the wing and nothing else.

Period.

You can have an airplane full of sandbags or nuns, and as long as that wing is moving through the air, lift WILL be generated. As long as those engines are producing thrust, it WILL accelerate.

As long as it is accelerating AND producing lift it WILL fly.

The wheels have nothing to do with anything. Even if they are moving at 1,000 miles per hour.

Sorry that is just the way it is.

Oh, yeah. Since we are throwing qualifications around, I have been around airplanes since I was young too, in fact several years before you were even born...and I fly them everyday, and I have an entire degree based on how they work, and I have read every single airplane book I could get my hands on from the age of 5 when I started learning to read ( I was actually looking at pictures at 4, but they didn't explain much). I have a closet full of books on airplanes if you ever want to come read them.

If those aren't enough for you, I can put you in touch with any number of friends that have a doctorate in any number of fields relating to this topic.

If you still think I am full of shit, go get a treadmill, and a rubber band airplane and try it out. It is a fun experiment. I know because I have seen it.

I want my Million Bucks!