...follow the link below:
http://pogue.blogs.nytimes.com/2006/...ill-conundrum/
Does the plane take off? Of course it bloody does. But another forum I post on have been posting for pages and pages arguing both ways. In fact here's a 443 page (and counting) thread on a physics forum on the same subject that has been going over a year:
http://forum.physorg.com/index.php?showtopic=2417
Answers below please
No, the aircraft would not take off, because for an aircraft to take off there needs to be sufficient airflow over the wings to generate lift, as seen in the picture below.
because of the shape of a wing it creates high pressure underneath the wing and low pressure above the wing, (thus unbalancing the forces) which would make the aicraft lift off the ground.
If an aircraft was on a treadmill then it would indeed be static thus no change in air pressure on the upper and lower of the wing itself.
However this is not to say that a harrier jumpjet would not take off
The plane needs to move forward against the neutral air. Thats the only function of the engines. If it could take off on a treadmill, it could take off with the brakes on.
nononononononononononono! I've seen this posted on every forum I go to, at one point or another. No, it won't take off
I call yes to this one.
no matter how fast the treadmill is turning against the wheels the plane will still take off as the wheels are just there to keep the whole thing off the ground.
The only thing you are going to get is a little drag due to friction between the treadmill, tyre and wheel bearings. The plane is still oing to take off.
Last edited by Funkstar; 14-12-2006 at 11:40 PM.
I thought this was about a sequel to Snakes on a Plane...
THE PLANE WILL TAKE OFF, providing it is travelling at succifcent speed.
Think about it...the plane is moving forwards against the air, otherwise it would fall off the treadmill. So say the treadmill is moving at 140 knots with a 737 stationary on it, the 737 would be able to take off on it
The engines in this instance will only exert enough force to keep the wheels on the treadmill, there wouldn't be any air flow over the wings imo. How can it possibly take off if there is little or no air moving over the wings? That is how the things get into the air in the first place.
The motion of it going through the air at speed splits the air to create positive and negative air pressures over and under the wing (I can't remember which way round it works). By doing this lift is created and the plane flies. The engines are there to drive it through the air and to maintain the force of air moving over and under the wing.
If the engines are only producing enough thrust to keep it on the treadmill then theres nothing to drive it into the air and the wheels will just spin faster and faster.
Last edited by Dorza; 14-12-2006 at 11:53 PM.
You're all wrong wrong wrong
On a plane, the wheels freely rotate. The acceleration comes from the engines mounted on the wings. The plane will take off entirely as normal, taxiing forwards down the treadmill until it builds up enough speed (relative to the air, and the ground away from the treadmill) to take off. The wheels will just be freely spinning twice as fast as normal.
The picture is a bit disingenuous because it implies the plane is stationary, which it is not. Sure enough, a car could not accelerate down the treadmill but a plane definitely can.
@MonkeyBum, you have accidentally arrived at the right answer but you reasoning is all wrong
@Dorza - the engines are indeed ON. Let's assume there is a pilot in the cockpit doing his best to take off.
Last edited by JPreston; 14-12-2006 at 11:46 PM. Reason: addressing a couple of late posts
But it IS moving against the air! Otherwise it would fall off the treadmill!Originally Posted by Dorza
Plus, depending on the speed, with no engines it could take off briefly before gliding back to the ground.
Nope your completely incorrect, even if the treadmill was moving at 1,000knots there would still be the same amount of airflow passing over the wings as if the aircraft was stationary, think about it for a minute...THE PLANE WILL TAKE OFF, providing it is travelling at succifcent speed.
Think about it...the plane is moving forwards against the air, otherwise it would fall off the treadmill. So say the treadmill is moving at 140 knots with a 737 stationary on it, the 737 would be able to take off on it
I realized that as soon as I posted. Edited
Ah balls, I'm bloody confused again.
Actually, Dorza has an interesting point.
But...
This sentance makes me thing that the treadmil will change it's speed to match whatever speed the weels are turning at. The will be increasing linearly all the time until the wheels leave the treadmil.The conveyer belt is designed to exactly match the speed of the wheels, moving in the opposite direction
The jets push the plane at 1mph, so the treadmil moves at 1mph. This makes the wheels run at 2mph. So the treadmill increases it's speed to 2mph, wheels are now at 3mph, plane still traveling at 1mph. Treadmill now increases to 3mph, wheels at 4mph etc. etc. etc.
however if you are to read this whole treadmill idea as some bizzare way to launch a plane, then no, it will just fall off the end without any thrust.
another way to think of this is. If you were sitting in a car on a conveyer belt which was going at about 100mph and the car was driving against the conveyer belt at 100mph. then you stuck your hand out the window at a slight upwards increment. Would your hand rise or stay stationary?
Stationary.
on the other hand, if you were travelling down a normal road at 100mph and stuck your hand out the window at a slight upwards increment would your hand rise or stay stationary?
It would rise.
This in effect is how your average aircraft wing would work.
It wont take off, the plane itself is stationary even tho the treadmill is moving under it and the wheel turning the plane itself has no airflow over the wings.
Demonstrate this by putting a bit of ribbon on the wing and seeing what it does, if there is air flowing over the wing then the ribbon will show it.
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