Will the Plane Take-Off - Merged with MythBusters Show Thread
08-18-2006, 09:02 AM
#42
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After thinking about this for a few mins I have come to the conclusion that yes the plane will fly. I think the frictionless analogy works the best because the treadmill type device with the plane is indirectly trying to create this enviornment. If there was a runway where there was absolutely no friction on the ground and you put a car on it, the wheels would just spin freely, however, if you put a plane on there, where movement is not determined by the wheels but rather a propeller or jet engine which causes thrust on the plane without using the wheels, the plane would move foward which could in turn get air under its wings and acheive lift. I think an easy experiment would be get a toy car and put it on a tread mill let it go and see what happens, (most likely either stands still or moves backwards.. Then put the same toy car on the treadmill with bottle rockets taped on it and then light the bottle rockets... im assuming that the car will move foward.
08-18-2006, 09:20 AM
#46
Safety Car
To answer this question, we need specific details regarding the plane, and the tire/belt.
We need to know the maximum amount of forward thrust a plane can produce.
We need to know the maximum amount of backward force the wheels can produce on the plane.
If the force of the thrust is higher than the force of the wheels, the plane with start to move forward relative to the ground. Once this happens, the plane with continue to move faster and faster, and eventually take off.
If the tires can keep up with the thrust, the plane will go no where. It will not move relative to the ground, and will never take off.
We need to know the maximum amount of forward thrust a plane can produce.
We need to know the maximum amount of backward force the wheels can produce on the plane.
If the force of the thrust is higher than the force of the wheels, the plane with start to move forward relative to the ground. Once this happens, the plane with continue to move faster and faster, and eventually take off.
If the tires can keep up with the thrust, the plane will go no where. It will not move relative to the ground, and will never take off.
08-18-2006, 09:27 AM
#47
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Originally Posted by badboy
If the force of the thrust is higher than the force of the wheels, the plane with start to move forward relative to the ground. Once this happens, the plane with continue to move faster and faster, and eventually take off.
If the tires can keep up with the thrust, the plane will go no where. It will not move relative to the ground, and will never take off.
If the tires can keep up with the thrust, the plane will go no where. It will not move relative to the ground, and will never take off.
Originally Posted by bigman
This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite
direction).
direction).
08-18-2006, 09:54 AM
#48
Creepy guy in the mirror.
Forget the wheels... The wheel only confuse the question. A plane needs wheels for only one thing - vertical support when on the ground. A plane can take off with skis, pontoons, wheels, whatever can move *freely* on the takeoff surface. That means that they freewheel and have next to no interaction with horizontal motion. A plane could theoretically take off from its belly if the runway were covered with marbles (I know that is ridiculous, but so is a runway sized conveyor).
Think of the trick where you pull a tablecloth out from under a bunch of dishes and the dishes remain in place. Why is that possible? Because a force (object at rest) is acting upon the dishes other than the force (friction) of the tablecloth.
The conveyor can only affect wheel speed. It cannot affect plane speed. The plane will take off with the wheels spinning twice as fast.
Think of the trick where you pull a tablecloth out from under a bunch of dishes and the dishes remain in place. Why is that possible? Because a force (object at rest) is acting upon the dishes other than the force (friction) of the tablecloth.
The conveyor can only affect wheel speed. It cannot affect plane speed. The plane will take off with the wheels spinning twice as fast.
08-18-2006, 10:16 AM
#49
The sizzle in the Steak
This thread AGAIN?!?!?!?!!? 
08-18-2006, 10:45 AM
#50
08-18-2006, 10:51 AM
#51
Nom Nom Nom Nom
Originally Posted by NSXNEXT
Without airflow over the wings there will be no lift. Without lift the plane cannot take off.
Someone please counter this argument.
Someone please counter this argument.
No lift=no fly.
08-18-2006, 11:00 AM
#53
Yeehaw
Originally Posted by NSXNEXT
Without airflow over the wings there will be no lift. Without lift the plane cannot take off.
Someone please counter this argument.
Someone please counter this argument.
Why wouldn't there be airflow? The plane would move forward just fine, it doesn't rely on traction with the ground to generate thrust. Again, think of this plane having a rope tied to it, and the rope pulling the plane forward. It doesn't matter how fast or in what direction the wheels are spinning, this rope is going to pull the plane forward. That rope = jet/propeller engine.
The purpose of the wheels is to keep the plane off the ground, not to move it in any certain direction. If you strapped wheels to a bottle rocket, you think it would stay in place?
08-18-2006, 11:09 AM
#54
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Originally Posted by BEETROOT
Why wouldn't there be airflow? The plane would move forward just fine, it doesn't rely on traction with the ground to generate thrust. Again, think of this plane having a rope tied to it, and the rope pulling the plane forward. It doesn't matter how fast or in what direction the wheels are spinning, this rope is going to pull the plane forward. That rope = jet/propeller engine.
The purpose of the wheels is to keep the plane off the ground, not to move it in any certain direction. If you strapped wheels to a bottle rocket, you think it would stay in place?
The purpose of the wheels is to keep the plane off the ground, not to move it in any certain direction. If you strapped wheels to a bottle rocket, you think it would stay in place?
So - at take off you could have a ground speed of 500 mph and an air speed of 200 mph? I hope that plane has speed rated tires!
08-18-2006, 11:11 AM
#55
Creepy guy in the mirror.
Originally Posted by NSXNEXT
Without airflow over the wings there will be no lift. Without lift the plane cannot take off.
Someone please counter this argument.
Someone please counter this argument.
What is being disputed is can the plane obtain forward motion that is required for lift, and the answer clearly is yes... Since that forward motion is obtained by thrust against the air behind the engines and the vacuum created in front of the engine. No treadmill is going to prevent that.
08-18-2006, 11:12 AM
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Beet, time to put the top up on that Jeep. You've been breathing too many fumes.
1) The plane is NOT moving, the wheels are.
2) Thrust is NOT lift. There is no airflow over the wings on a plane that is not moving.
The car dyno is a good example. Is the car moving? No the wheels are. Is there air flowing over the hood of the car? No that's why they put the fans in front of the car to keep the engine temp cooler.
1) The plane is NOT moving, the wheels are.
2) Thrust is NOT lift. There is no airflow over the wings on a plane that is not moving.
The car dyno is a good example. Is the car moving? No the wheels are. Is there air flowing over the hood of the car? No that's why they put the fans in front of the car to keep the engine temp cooler.
08-18-2006, 11:13 AM
#57
Yeehaw
No, I'm saying it doesn't matter what the conveyor belt is doing. The tires would be spinning faster, but your ground speed/air speed would be nearly identical to your speed if you were taking off on solid ground. The tires can spin freely in any direction they want, so long as they aren't acting as brakes somehow, they don't have any influence on the forward motion of the plane, since that is determined by thrust of the engine and the air, not the wheels and the ground.
08-18-2006, 11:15 AM
#58
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Originally Posted by BEETROOT
No, I'm saying it doesn't matter what the conveyor belt is doing. The tires would be spinning faster, but your ground speed/air speed would be nearly identical to your speed if you were taking off on solid ground. The tires can spin freely in any direction they want, so long as they aren't acting as brakes somehow, they don't have any influence on the forward motion of the plane, since that is determined by thrust of the engine and the air, not the wheels and the ground.
I've switched teams - I'm with Beet!
08-18-2006, 11:15 AM
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Originally Posted by JLatimer
You are absolutely correct and that cannot be disputed.
What is being disputed is can the plane obtain forward motion that is required for lift, and the answer clearly is yes... Since that forward motion is obtained by thrust against the air behind the engines and the vacuum created in front of the engine. No treadmill is going to prevent that.
What is being disputed is can the plane obtain forward motion that is required for lift, and the answer clearly is yes... Since that forward motion is obtained by thrust against the air behind the engines and the vacuum created in front of the engine. No treadmill is going to prevent that.
Yes but thrust is not what allows an airplane to rise above the ground. LIFT does that and without sufficient airflow that ain't gonna happen.
08-18-2006, 11:16 AM
#60
Yeehaw
Originally Posted by NSXNEXT
Beet, time to put the top up on that Jeep. You've been breathing too many fumes.
1) The plane is NOT moving, the wheels are.
2) Thrust is NOT lift. There is no airflow over the wings on a plane that is not moving.
The car dyno is a good example. Is the car moving? No the wheels are. Is there air flowing over the hood of the car? No that's why they put the fans in front of the car to keep the engine temp cooler.
1) The plane is NOT moving, the wheels are.
2) Thrust is NOT lift. There is no airflow over the wings on a plane that is not moving.
The car dyno is a good example. Is the car moving? No the wheels are. Is there air flowing over the hood of the car? No that's why they put the fans in front of the car to keep the engine temp cooler.
I'm aware the thrust isn't what causes the plane to fly. What I'm saying is that thrust would not be countered by a spinning treadmill, like it would on a car.
08-18-2006, 11:17 AM
#61
Nom Nom Nom Nom
Originally Posted by BEETROOT
Why wouldn't there be airflow? The plane would move forward just fine, it doesn't rely on traction with the ground to generate thrust. Again, think of this plane having a rope tied to it, and the rope pulling the plane forward. It doesn't matter how fast or in what direction the wheels are spinning, this rope is going to pull the plane forward. That rope = jet/propeller engine.
The purpose of the wheels is to keep the plane off the ground, not to move it in any certain direction. If you strapped wheels to a bottle rocket, you think it would stay in place?
The purpose of the wheels is to keep the plane off the ground, not to move it in any certain direction. If you strapped wheels to a bottle rocket, you think it would stay in place?
Here is a good example..
This all has nothing to do with the wheels. It all has to do with relative wind. The airplane is staying in the exact same spot until it is able to leave the ground (conveyor belt). There is no relative wind. It can not fly. The engines provide zero lifting force. The only reason airplanes have engines is to provide a forward motion to generate relative wind so that the air moves faster over the wing to create a lower pressure.
Its kinda like the principle of aircraft carriers. Planes are slingshot off of the platform to provide forward motion. Why? Only to generate relative wind in a shorter amount of distance.
Its like if you were running on a treadmill. You feel no wind against your face because you are not moving forward. Where as if you were running down the street you feel wind (relative wind [relative because of your forward motion through the air]).
Its kinda like the principle of aircraft carriers. Planes are slingshot off of the platform to provide forward motion. Why? Only to generate relative wind in a shorter amount of distance.
Its like if you were running on a treadmill. You feel no wind against your face because you are not moving forward. Where as if you were running down the street you feel wind (relative wind [relative because of your forward motion through the air]).
http://digg.com/general_sciences/Phy...lane_take_off_
08-18-2006, 11:17 AM
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Originally Posted by NSXNEXT
Yes but thrust is not what allows an airplane to rise above the ground. LIFT does that and without sufficient airflow that ain't gonna happen.
Given thrust - the plane will move through air regardless of what the wheels or belt are doing.
08-18-2006, 11:18 AM
#63
Yeehaw
Originally Posted by NSXNEXT
Yes but thrust is not what allows an airplane to rise above the ground. LIFT does that and without sufficient airflow that ain't gonna happen.
That thrust pulls the plane forward, no matter what the wheels are doing. The wheels are only there to provide frictionless contact with the ground, to allow the engine to move the plane. If you replaced the wheels with blocks of ice that could slide along the ground, the plane could still take off just fine.
08-18-2006, 11:20 AM
#64
Yeehaw
Originally Posted by SwervinCL
There wouldnt be any airflow because the plane would still be stationary. All the engines on a plane does is generate forward thrust. You could turn the afterburners on and the plane is still going to be sitting in the same place.
Here is a good example..
Heres the link
http://digg.com/general_sciences/Phy...lane_take_off_
Here is a good example..
Heres the link
http://digg.com/general_sciences/Phy...lane_take_off_
thats wrong.
When you run you feel no wind because you aren't moving, because the treadmill counters your legs spinning. If you had a jetpack on your back you would fly right off the thing.
I better be right on this or I'm going to have both feet in my mouth...
08-18-2006, 11:21 AM
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Originally Posted by fla-tls
Yes - but the counterforce to thrust is drag - not any resistance that would be provided by a conveyor belt.
Given thrust - the plane will move through air regardless of what the wheels or belt are doing.
Given thrust - the plane will move through air regardless of what the wheels or belt are doing.
HOW THE HELL IS THE PLANE GOING TO GET UP IN THE AIR WITHOUT ANY LIFT? Where is the airflow over the wings?
08-18-2006, 11:22 AM
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Originally Posted by BEETROOT
...the plane could still take off just fine.
08-18-2006, 11:23 AM
#67
Yeehaw
Originally Posted by NSXNEXT
HOW THE HELL IS THE PLANE GOING TO GET UP IN THE AIR WITHOUT ANY LIFT? Where is the airflow over the wings?
Originally Posted by NSXNEXT
Because of the air pressure above and below the wings. How can there be any air pressure if the body/wings are not physically moving through the air?
The thrust from the engines is still going to move the plane forward, just like it would on a normal runway. It will still be moving along the runway. A spinning treadmill under the wheels doesn't matter, its not going to hold the plane in place. The wheels would spin faster, but the plane would move forward the same as normal, thus generating the same lift from the same airflow over the wings.
08-18-2006, 11:28 AM
#68
Interesting. Interesting.
Originally Posted by BEETROOT
The thrust from the engines is still going to move the plane forward, just like it would on a normal runway. It will still be moving along the runway. A spinning treadmill under the wheels doesn't matter, its not going to hold the plane in place. The wheels would spin faster, but the plane would move forward the same as normal, thus generating the same lift from the same airflow over the wings.
08-18-2006, 11:29 AM
#69
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Originally Posted by BEETROOT
The thrust from the engines is still going to move the plane forward, just like it would on a normal runway. It will still be moving along the runway. A spinning treadmill under the wheels doesn't matter, its not going to hold the plane in place. The wheels would spin faster, but the plane would move forward the same as normal, thus generating the same lift from the same airflow over the wings.
Originally Posted by bigman
A plane is standing on a runway that can move (some sort of band conveyer).
The plane moves in one direction, while the conveyer moves in the opposite
direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite
direction).The question is:Will the plane take off or not?
The plane moves in one direction, while the conveyer moves in the opposite
direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite
direction).The question is:Will the plane take off or not?
It's a big belt on the ground that matches the wheel speed of the plane. The more thrust the plane makes the more it turns the wheels against the conveyor which in turns causes the conveyor belt to turn faster
08-18-2006, 11:29 AM
#70
Nom Nom Nom Nom
Originally Posted by BEETROOT
thats wrong.
When you run you feel no wind because you aren't moving, because the treadmill counters your legs spinning. If you had a jetpack on your back you would fly right off the thing.
I better be right on this or I'm going to have both feet in my mouth...
When you run you feel no wind because you aren't moving, because the treadmill counters your legs spinning. If you had a jetpack on your back you would fly right off the thing.
I better be right on this or I'm going to have both feet in my mouth...
A jetpack is different from a plane. A jetpack utilized thrust to lift it off the ground. Aplane utilizes its wings + thrust to lift the plane off the ground.
If you took the wings off a plane, you think it would still fly?
08-18-2006, 11:30 AM
#71
Suzuka Master
Originally Posted by NSXNEXT
Because of the air pressure above and below the wings. How can there be any air pressure if the body/wings are not physically moving through the air?
The engines on a jet create thrust. This thrust is applied to the air. The only thing that could stop the plane from taking off is too strong a headwind.
08-18-2006, 11:32 AM
#73
Not Registered
Get treadmill, go to Wal-Mart and buy toy plane which has wheel that spin. Crank up treadmill to any speed you want too. With hand, place plane on treadmill... the wheel of the plane start spinning really fast! Now move the plane at any speed down treadmill with you hand. With the movement going forward the treadmill speed and wheel speed are still matched, but you can move forward. You hand is acting as thrust... it's pushing the plane forward just as a propeller or exhaust pushes. Moving forward will create airflow and lift. Are all you people saying that it's impossible for you to move the plane... it just sits at one spot on the treadmill and your hand can't move it?
Last edited by Bdog; 08-18-2006 at 11:34 AM.
08-18-2006, 11:32 AM
#74
Creepy guy in the mirror.
Originally Posted by NSXNEXT
Yes but thrust is not what allows an airplane to rise above the ground. LIFT does that and without sufficient airflow that ain't gonna happen.
The answer is no.
Does the plane rely on ground contact for forward motion?
The answer is no.
Can the engines provide force against surrounding air?
The answer is yes.
Will that force try to move the plane forward?
Yes.
Will the treadmill move faster in response to the forward motion?
Yes.
Will the freewheeling wheels counteract the forward motion created by thrust?
No.
Will the treadmill move faster in response to the forward motion?
Yes.
Will the freewheeling wheels counteract the forward motion created by thrust?
No.
... Takeoff.
08-18-2006, 11:33 AM
#75
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Originally Posted by mclarenf3387
Forget the wheels, the wheels on a plane will spin foward or reverse with nearly zero friction.
The engines on a jet create thrust. This thrust is applied to the air. The only thing that could stop the plane from taking off is too strong a headwind.
The engines on a jet create thrust. This thrust is applied to the air. The only thing that could stop the plane from taking off is too strong a headwind.
But Brett it's sitting on a conveyor belt that prevents it from moving forward. The faster the plane goes, the faster the belt turns in the opposite direction. How is the plane going to move forward?
08-18-2006, 11:33 AM
#77
Suzuka Master
Originally Posted by NSXNEXT
Swervin, I feel like this is a joke thread and the only ones not in on it are you and me. 
08-18-2006, 11:33 AM
#78
Yeehaw
Originally Posted by NSXNEXT
It's like the conveyor belt on a MANUAL treadmill (one without a motor. The faster you run the faster the belt moves. Do you move forward on that? No of course not. Why would this be any different.
It's a big belt on the ground that matches the wheel speed of the plane. The more thrust the plane makes the more it turns the wheels against the conveyor which in turns causes the conveyor belt to turn faster
It's a big belt on the ground that matches the wheel speed of the plane. The more thrust the plane makes the more it turns the wheels against the conveyor which in turns causes the conveyor belt to turn faster
Originally Posted by SwervinCL
Insert your feet, because you are wrong.
A jetpack is different from a plane. A jetpack utilized thrust to lift it off the ground. Aplane utilizes its wings + thrust to lift the plane off the ground.
If you took the wings off a plane, you think it would still fly?
A jetpack is different from a plane. A jetpack utilized thrust to lift it off the ground. Aplane utilizes its wings + thrust to lift the plane off the ground.
If you took the wings off a plane, you think it would still fly?
08-18-2006, 11:36 AM
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OK let's try this a different way.
The plane is stopped on the runway at position 0
The plane's engine go to full powers causing the plane to begin to move
At that exact same moment the conveyor belt senses movements and begins to move at the exact same speed in the opposite direction
The plane's wheels continue to move but the plane is stuck at postion 0 because the conveyor belt matches its speed.
The plane is stopped on the runway at position 0
The plane's engine go to full powers causing the plane to begin to move
At that exact same moment the conveyor belt senses movements and begins to move at the exact same speed in the opposite direction
The plane's wheels continue to move but the plane is stuck at postion 0 because the conveyor belt matches its speed.
