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About LinkBacksthe plane will take off.
imagine the wheels as yo-yo's just spinning at the bottom of the string, now imagine you put your yo-yo on a treadmill whilst you walk forward off to the side of it, the yo yo goes with you doesn't it.
the plane will take off.
imagine the wheels as yo-yo's just spinning at the bottom of the string, now imagine you put your yo-yo on a treadmill whilst you walk forward off to the side of it, the yo yo goes with you doesn't it.
"The less you eat, drink and buy books; the less you go to the theatre, the dance hall, the public house; the less you think, love, theorise, sing, paint, fence, etc., the more you save – the greater becomes your treasure which neither moths nor rust will devour – your capital. The less you are, the less you express your own life, the more you have, the greater is your alienated life, the greater is the store of your estranged being." Karl Marx
But it's not stationary, the plane will move down the the tread mill (which hypothetically is as long as a normal runway). All thats happening is that the the wheel would move faster.Originally Posted by Steve B
Nick, Funkstar and everyone else saying it would take off are right.
Imagine you are walking on a treadmill. You are walking as the same speed as the treadmill so you are stationary. Now you throw a ball in front of you - the ball still flies through the air away from you as normal. This is because the force moving the ball is not being effected by the treadmill. The engines, wings and take off are independent of the treadmill.
If the plane could not take off from the treadmill, it would not take off on a normal runway either.
You would need a wind tunnel with the wind blowing back against the plane to stop it taking off.
Last edited by autopilot; 15-12-2006 at 12:09 PM.
That's the most opaque explanation for anything, ever
It really is as simple as that. Why can't people understand...
The plane takes off.
Don't trouble yourselves any further.
The situation as stated is that the plane is on a treadmill, and the treadmill matches the speed of the plane. That means that however much thrust is generated by the engines, and however fast the wheels turn, the treadmill will keep up.
The plane will move along the rolling surface of the treadmill at whatever speed the engines are able to generate, but, crucially, relative to the air around it, it will be stationary. That means that there is no airflow over the wing, and it is airflow over the wing that generates lift. Without lift, the plane will not take off.
autopilot is incorrect; the distinction is that a plane on a runway is actually generating airflow over the wing because it is actually moving through the air around it. The plane on a treadmill is not.
The plane can roll along the rolling surface of the treadmill as fast as it likes; it still won't take off.
he speaks the truth
The crucial part is that the problem states that plane is stationary, lift is due to airflow over the wings. if there is no forward movement, there is no airflow over the wings, there is no lift.
If however the plane manages to move along the treadmill (how?) then the plane can take off. The issue here appears to be 'does the plane move', rather than 'does the plane take off'...
alternatively. what would happen if you stuck a jet engine on top of a car, with the car on the treadmill. there is a massive amount of forward force, but this would all be countered by the treadmill.
LOL! I cant believe you think that
The plane is moving across the treadmill, thus the plane is moving through the air and generating lift as normal.
I give up!
But....the thrust does not come from the wheels on a plane...you are thinking as though it were a car or something.
If the plane was stationary, which it is not, then that would be true. But the plane is able to move exactly as normal. Imagine it were on ice skates, or it was a sea-plane. It doesn't matter what the wheels or treadmill do, the thrust develops from the engines on the wings...
1. That distinction does not occur, because the wheels aren't driven - the plane still moves through the air.
2. It moves through the air at exactly the same speed as the plane on the runway....
3. ....it just happens to be moving twice as fast relative to the (irrelevant) runway.
4. YES IT DOES
No it would not. If a jet was attached to a car it to would also fly down the run way as long at the wheels were free moving.
Your all completely mad i tell you
Unless your contention is that as the treadmill moves backwards, it's pulling the atmosphere with it, you're incorrect. The reality is that the air is not moving, the plane is not moving relative to the air, the only thing that IS moving is the rolling surface of the treadmill. The plane is not moving relative to the air around it, so there's no lift being generated. So it won't take off.LOL! I cant believe you think that
The plane is moving across the treadmill, thus the plane is moving through the air and generating lift as normal.
I give up!
Here is a good explaination from another site;
I don't think this is a really tough question, but as Kottke points out, having some beginning physics helps. Imagine the plane is on a completely frictionless surface (oil so slick, friction between the tires and the ground is absolutely zero). A car on that surface couldn't budge. A plane, however, will move, since the force that propels it is independent of the ground. As a matter of fact, the wheels on the plane are acting just like a frictionless surface, allowing the planes propulsion (prop, jet, rubber bands, etc.) to create forward force. (where the lift comes from seems to be common knowledge amongst all the commentors here)
Same principle applies with the belt that equals the speed of the plane. The belt moves faster as the plane speeds up, resulting in the wheels spinning twice as fast (as compared to not have the belt/runway). Since the forward force (thrust, push, pull... it doesn't matter in a force diagram) is independent of the ground, the plane takes off.
But thats the whole point!!! Thats why the planes jets will push it along at normal speed.
The treadmill has no effect on the air around the plane or its jets propulsion.
How do you think a Harrier Jump Jet takes off?
Nope, that's wrong.
For a treadmill to match the speed of the plane is physically AND theoretically impossible due to the relative movement of the objects involved.
First, let's look at the treadmill/wheel movement. The crucial thing to note here is that the wheels are free-wheeling and provide no form of thrust or force upon the plane. Therefore the speed at which the wheels spin is actually irrelevant to whether the plane takes off or not.
Say, for example, the lift off speed of a plane is 100 mph. If there was a 40mph headwind, the take off speed of the plane is still 100mph yes?
But the speed the plane takes off at, relative to a stationary object beside the runway, is only 60mph because the air is already flowing over the wings at 40mph, even when the plane is standing still.
You can't disagree with that one, it's a fact and is in fact the very basis of aviation in choosing which runway and which direction to take off in... you always head into wind to get that extra bit of help from the wind coming at you quicker.
So, now you're wondering what this has to do with the treadmill and wheels? Nothing.
And that's the whole point. The Plane could not have any wheels at all, (as per my earlier floatplane example) or it could be skidding along on ice with locked up brakes, what the wheels are doing is irrelevant. They don't provide any sort of thrust or forward motion so how they interact with a surface, be it ice, water or a giant treadmill going at supersonic speeds is completely independent of the planes engines thrusting against the air.
If this wasn't so, please explain how a float plane takes off on water, an example which is entirely relevant to this argument as the water can be likened to the treadmill very easily... it provides no traction for the plane whatsoever, just like a treadmill running in the opposite direction to the plane's movement.
No, I am not; thrust is generated, the plane moves relative to the treadmill on wheels, which rotate, though unpowered.
The plane IS stationary relative to everything but the rolling surface of the treadmill. If the treadmill were next to a house, for the purposes of demonstration, would the plane move relative to the house? No. It's not moving relative to the air either.
If it were on skates, skis, skids, or floats, it would still be moving relative to its environment, and more specifically the air around it. On the treadmill it does NOT move relative to anything but the rolling surface of the treadmill. To the man standing next to it, it is stationary, and it is stationary with regard to the air around it too. No movement relative to air, no lift. No lift, no fly.
No, it doesn't. Unless your contention is that the treadmill is somehow sucking the atmosphere along as well.
It doesn't move through the air at all.
The runway and treadmill are both irrelevant; what counts is is the wing moving forward relative to the air around it. The air isn't moving, only the treadmill surface is. So the wing is NOT moving relative to the air around it, therefore it is not generating lift, therefore the plane stays on the ground.
No, it doesn't.4. YES IT DOES
lets ignore the treadmill for a minute.
The engines on planes are used to move the plane down the runway fast enough so that the air flowing over the wings is enough to create lift. when this occurs the plane takes off and then the plane flies around
The plane is not floating at this point, its on the ground. the wheels are on the tarmac and are turning as the plane trundles along. as the plane goes faster, the wheels turn faster, the engines may still be giving the same amount of thrust, but the plane is accelerating along the ground, wheels in contact with the tarmac, turning faster and faster.
If you replace the tarmac with a treadmill, as the wheels turn faster, the treadmill runs faster, counter-acting the movement. the wheels can be going 1000mph, but the treadmill will be doing -1000mph, so the relative speed is 0. the plane cant move.
What am i missing, because I really cant see the otherside of this argument
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