January 28, 200817 yr OverlordQ;542071']Your analogy fails, by grabbing the rails, you're exerting a force outside your system. Your system would be You, the skateboard, the treadmill. Better analogy is sit on the skateboard and try and push yourself forward by pushing off the belt. Also, yes the thrust doesn't come from the wheels, but the lift comes from the air moving over the airfoil. If the plane doesn't increase it velocity relative to the air it wont get enough lift to take off. The force I am exerting outside my system would be the exact same as the force that an airplanes engine would do to the air. When the engines blow the air, it will create a forward thrust the same as my arms do. So the engines constantly pushing would make the whole airplane move forward which would make the air move around the wings which would make lift allowing the plane to fly. By pushing off the belt like you suggest, the system would be similar to a car where the thrust is coming from a forcer being exerted on the ground using friction. With the airplane, the tires' rotation on the ground is only relative to the forward motion of the airplane and the reverse motion of the treadmill which has no relation to the air moving around the wings. An airplane would not fly if the force came from the wheels because there is no ground to drive on while you are flying, that is why airplane engines move air.
January 28, 200817 yr De3emon is correct. The force of the airplane's engine would counter-act the movement of the treadmill. However in order for the plane to be able to take off it would have to work harder then normal if the belt was turning in the opposite direction. The following is by no means accurate as they're random numbers. Normal take off = 100 Foot pounds of Thrust Speed to take off = 100 mph Belt speed = 20 mph In order for a plane to be able to take off from the belt... the engine would need to produce 120 foot pounds of thrust. In other words it would have to make up for the negative force being placed on the entity by the conveyor belt.
January 28, 200817 yr De3emon is correct. The force of the airplane's engine would counter-act the movement of the treadmill. However in order for the plane to be able to take off it would have to work harder then normal if the belt was turning in the opposite direction. The following is by no means accurate as they're random numbers. Normal take off = 100 Foot pounds of Thrust Speed to take off = 100 mph Belt speed = 20 mph In order for a plane to be able to take off from the belt... the engine would need to produce 120 foot pounds of thrust. In other words it would have to make up for the negative force being placed on the entity by the conveyor belt. That would only be true if the wheels needed a real good oiling or if the plane had no wheels. The extra force needed would be minimal. The point of the wheels on an airplane is to allow it to move along the ground freely. If the ground moves in the opposite direction then the wheels just turn faster and if the engines were working to try and make the plane take off they would only be given a minimal amount of extra work that would be needed in order to move the plane to take off. This is why it is easy to move freely on that skateboard while the treadmill is moving.
January 28, 200817 yr I know that...and thats why I pulled numbers out of my ass because I've not done the experiment. My point is what ever force is added against the plane the engine/prop would have to make up for.
January 28, 200817 yr OverlordQ;542071']Your analogy fails, by grabbing the rails, you're exerting a force outside your system. Your system would be You, the skateboard, the treadmill. Better analogy is sit on the skateboard and try and push yourself forward by pushing off the belt. Also, yes the thrust doesn't come from the wheels, but the lift comes from the air moving over the airfoil. If the plane doesn't increase it velocity relative to the air it wont get enough lift to take off. better yet, you sitting on a skateboard holding on to a rope connected to a winch(winch=propeller pulling into the air), the rope will still be able to pull you making you move forward and your wheels spin faster, so yes it can work
January 28, 200817 yr it wont fly, go to school you stoner idiots, also this thread is copied from 4chan. ultimate recipe of pure failure.
January 29, 200817 yr Wow people are stupid... Planes aren't driven by their WHEELS. You can turn the belt/wheels as fast as you want and it doesn't change anything. The plane will still move forward when the engine is engaged. Therefor if the belt is long enough for a normal take off, then the plane will take off exactly as it normally does, the wheels will just be rolling at a much faster rate. Been discussed a thousand times over, always with the same result... You don't seem to understand. The conveyor belt is moving the OPPOSITE direction as the plane. It will be accelerating but it will not be displacing any position.
January 29, 200817 yr http://images.main.uab.edu/mediarelations/siteadmin/releaseimages/limited/big/lecture_mythbusters_kari_1.jpg
January 29, 200817 yr You don't seem to understand. The conveyor belt is moving the OPPOSITE direction as the plane. It will be accelerating but it will not be displacing any position. People really, really do not understand simple physics. It does not matter how fast the treadmill is moving in the opposite direction because the wheels only act as a tool to eliminate most friction between the plane and the ground. Put a heavy cube on a table cloth and try to pull it from underneath the cube, the cube will probably move quite a bit. Put a heavy sphere on a table cloth and pull the cloth from underneath, notice how to ball rolls making it easier to pull the cloth from underneath.
January 29, 200817 yr What are yall talking about? The wheel speed on the plane has nothing to do with take off. It doesn't matter how fast or slow the wheels are turning because planes are powered by jets/propellers. Treadmills ONLY affect wheel speed. Put a plane on skies or pontoons and have it take off from water or snow (wheel speed = 0) and it'll still take off. If you took a jumbo jet welded the wheels stationary (wheel speed = 0) (and assuming the rubber wouldn't tear itself to pieces) the plane will STILL take off. I feel like I'm taking crazy pills. Just because the wheels don't move (or are moving in the 'wrong' direction), does NOT mean the plane can't move. Unless for some stupid reason you guys are saying the plane is strapped stationary onto a conveyor belt. here's the equation for lift: L = (1/2)d*v^2*s*CL (http://www.grc.nasa.gov/WWW/K-12/WindTunnel/Activities/lift_formula.html) * L = Lift, which must equal the airplane's weight in pounds * d = density of the air. This will change due to altitude. These values can be found in a I.C.A.O. Standard Atmosphere Table. * v = velocity of an aircraft expressed in feet per second * s = the wing area of an aircraft in square feet * CL = Coefficient of lift , which is determined by the type of airfoil and angle of attack. Notice how wheel speed is NOT in there. So in order to achieve lift, your wheels could be spinning in 360's, backwards, inside out, back in time, and sideways and you'd still take off. Sure, some people may say, "omg if the wheels are spinning backwards the plane can't go forward and therefore velocity = 0!!!" But you're an idiot. Have you ever slammed on the brakes in your car (without ABS)...the tires lock up. "omg the wheels aren't spinning but you're still moving!!" Or maybe if you put the car in reverse on an icy hill, "omg the wheels are spinning backwards but you're going forward! witchcraft!" Gravity in this case is acting like the jets/propellers on the plane. Wheel speed has NOTHING to do with airplane speed. Which is evident once again, in that if I told you an airplane's wheels are spinning at 200rpm, you could tell me NOTHING about the plane's speed. God, I can't wait till mythbusters finally does this... edit: 10 seconds on youtube gives me this:
January 29, 200817 yr the engines must propel the plane to move significantly faster than the belt while the wheels are in contact with that belt. the plane must be moving through the air, it absolutely cannot remain in the same spot over the ground with the engines running; without the plane going through the air, there exists no lift. in short, no movement = no lift. assuming of course the treadmill is moving in the direction opposite of the intended direction of the plane. QED
January 29, 200817 yr What are yall talking about? The wheel speed on the plane has nothing to do with take off. It doesn't matter how fast or slow the wheels are turning because planes are powered by jets/propellers. Treadmills ONLY affect wheel speed. Put a plane on skies or pontoons and have it take off from water or snow (wheel speed = 0) and it'll still take off. If you took a jumbo jet welded the wheels stationary (wheel speed = 0) (and assuming the rubber wouldn't tear itself to pieces) the plane will STILL take off. I feel like I'm taking crazy pills. Just because the wheels don't move (or are moving in the 'wrong' direction), does NOT mean the plane can't move. Unless for some stupid reason you guys are saying the plane is strapped stationary onto a conveyor belt. here's the equation for lift: L = (1/2)d*v^2*s*CL (http://www.grc.nasa.gov/WWW/K-12/WindTunnel/Activities/lift_formula.html) * L = Lift, which must equal the airplane's weight in pounds * d = density of the air. This will change due to altitude. These values can be found in a I.C.A.O. Standard Atmosphere Table. * v = velocity of an aircraft expressed in feet per second * s = the wing area of an aircraft in square feet * CL = Coefficient of lift , which is determined by the type of airfoil and angle of attack. Notice how wheel speed is NOT in there. So in order to achieve lift, your wheels could be spinning in 360's, backwards, inside out, back in time, and sideways and you'd still take off. Sure, some people may say, "omg if the wheels are spinning backwards the plane can't go forward and therefore velocity = 0!!!" But you're an idiot. Have you ever slammed on the brakes in your car (without ABS)...the tires lock up. "omg the wheels aren't spinning but you're still moving!!" Or maybe if you put the car in reverse on an icy hill, "omg the wheels are spinning backwards but you're going forward! witchcraft!" Gravity in this case is acting like the jets/propellers on the plane. Wheel speed has NOTHING to do with airplane speed. Which is evident once again, in that if I told you an airplane's wheels are spinning at 200rpm, you could tell me NOTHING about the plane's speed. God, I can't wait till mythbusters finally does this... edit: 10 seconds on youtube gives me this: Wheel speed is not in the equation, but the velocity of the plane is. How is it supposed to gain velocity without wheel speed? The wheel speed will being driving the plane forward, while the conveyor belt will be driving the plane backwards, thus the net velocity is 0. If you plug that into your equation, you get L=0! And unless your plane weighs 0 pounds, you can't liftoff. I just owned you with your own data. How do you feel? I feel great.
January 29, 200817 yr mythbusters experiments have never been accurate to begin with. almost every episode is a joke. then came smash lab or is it crash lab? smash lab. and i disagree, mythbusters actually does some legit stuff.
January 29, 200817 yr How is it supposed to gain velocity without wheel speed? When the plane is in the air, how does it gain speed without wheel speed? Oh that's right...with the ENGINES. How does a plane gain speed on the ground? With the ENGINES. If you welded the tires stationary, and put the plane on ice, I would bet money the plane will still be able to move forward. The wheel speed will being driving the plane forward, while the conveyor belt will be driving the plane backwards, thus the net velocity is 0. The conveyor is not driving the plane backwards. The conveyor is spinning the wheels backwards, and due to small amounts of friction between the ground and wheels and bearings in those wheels, the plane will drift backwards. Yes, there is a difference. So the thrust of the engine ONLY has to overcome that small amount of friction to move the plane forward, and seeing as the engines can propel a multiple ton object forward at hundreds of miles per hours...I think it can handle some small bearing friction. I just owned you with your own data. How do you feel? I feel great. You're an idiot. If you watched that youtube video I posted, you would clearly see the plane is quite easily able to move itself forward on a treadmill. The whole concept of this is stupid, I just can not believe people believe that the plane can not take off. A plane is not a car, the wheels ONLY support the plane and act as a bearing between the plane and the ground, they are absolutely not a determining factor in the planes speed. A very, very similar problem would be, "could a water plane take off on a river, if the current was flowing backwards?" You better bet it could.
January 29, 200817 yr Author yea people have already debated this to death on pretty much every existing forum on the internet.. i was just letting you guys know it was going to be on mythbusters finally..
January 30, 200817 yr Jedi Pimp is wrong... The thrust is created by engines, the movement of a plane has nothing to do with the speed that the wheels turn. When an airplane is in the air do its wheels touch the ground? No, but it still flies. The conveyor belt will be moving in the opposite direction of the plane, the ground will be still and the air will not move, the same way it is when a plane takes off. So to take off the plane pushes the air to move itself forward to make the air move around the wings to create lift. I have said this over and over but people do not understand. So why will it not move forward compared to the stationary ground? Here look, a video
January 30, 200817 yr Damn, some of you are even more stupid than I thought. Wheel speed? velocity? more stupidness? Planes are not powered by their wheels J-P. You can spin the wheels on the fastest conveyor belt in the world, and as soon as the planes engines start going the plane will start moving forward on the belt, creating lift, then flying. Fans on the front? RIFK. You don't need fans on the front when the plane will move forward on the belt as if it wasn't even there. This is because, as I stated earlier, planes are not powered by their wheels, they are powered by their propellers, which are not being effected by the moving belt. ALL OF YOU THAT ARE SAYING IT DOESN'T WORK GO BACK TO SCHOOL. As I said earlier, it has already been done MANY times, and has worked EVERY TIME.
January 30, 200817 yr Jedi Pimp is wrong... The thrust is created by engines, the movement of a plane has nothing to do with the speed that the wheels turn. When an airplane is in the air do its wheels touch the ground? No, but it still flies. The conveyor belt will be moving in the opposite direction of the plane, the ground will be still and the air will not move, the same way it is when a plane takes off. So to take off the plane pushes the air to move itself forward to make the air move around the wings to create lift. I have said this over and over but people do not understand. So why will it not move forward compared to the stationary ground? Yeah, we know that planes have engines. But the plane will start at rest on a conveyor belt with friction, therefore the wheels must LIFT OFF before they are no longer a factor. Until the plane lifts off, the velocity of the plane created by the engines will equal the wheel speed, and the conveyor belt moving the opposite direction at the same velocity will make the net velocity 0. Therefore the airplane will not move and will not lift off. However, if the velocity of the airplane is greater than the negative velocity of the conveyor belt, it CAN move forward on the belt. This is not debated though, since the circumstances require that the belt's velocity equal the airplane's. The plane will not take off, I guarantee it. If it does, may my forums account be banned.
January 30, 200817 yr the velocity of the plane created by the engines will equal the wheel speed, and the conveyor belt moving the opposite direction at the same velocity will make the net velocity 0. How many times does it have to be explained to you? lol wheel speed has nothing to do with the plane moving forward, therefor the belt has nothing to do with the plane moving forward. You can spin the wheels as fast as you want, but the AIR around the plane is still. As soon as you run the engine, the propeller will use the AIR to move forward on the belt as if it wasn't even there. Read this next part about 10 times : The plane moves by AIR and PROPELLER, not wheels or wheel speed, or the ground speed. THIS EXPERIMENT HAS BEEN DONE MANY TIMES WITH THE SAME RESULT, WHY DO YOU PEPOPLE INSIST ON ARGUING WHAT HAS BEEN PROVEN?
January 30, 200817 yr How many times does it have to be explained to you? lol wheel speed has nothing to do with the plane moving forward, therefor the belt has nothing to do with the plane moving forward. You can spin the wheels as fast as you want, but the AIR around the plane is still. As soon as you run the engine, the propeller will use the AIR to move forward on the belt as if it wasn't even there. Read this next part about 10 times : The plane moves by AIR and PROPELLER, not wheels or wheel speed, or the ground speed. THIS EXPERIMENT HAS BEEN DONE MANY TIMES WITH THE SAME RESULT, WHY DO YOU PEPOPLE INSIST ON ARGUING WHAT HAS BEEN PROVEN? JUST WATCH THAT IF YOU DO NOT UNDERSTAND LOL. The guy in the video said it himself, and it is contradictory to his experiment: The plane has to overcome the friction for it to be able to beat the velocity of the belt. Given the restraints of the problem (both the plane and the belt starting from rest and accelerating uniformly) the plane will not overcome the ground friction and the plane will not lift off. I swear on the life of every Jewish soul that it won't lift off.
January 30, 200817 yr LOL. The guy in the video said it himself, and it is contradictory to his experiment: The plane has to overcome the friction for it to be able to beat the velocity of the belt. Given the restraints of the problem (both the plane and the belt starting from rest and accelerating uniformly) the plane will not overcome the ground friction and the plane will not lift off. I swear on the life of every Jewish soul that it won't lift off. If the belt moves at 10 m/s and the plane moves at 10m/s then the plane will be moving forward because the wheels have almost nothing to do with the motion of the plane and if you would have watched the video you would understand that because when he stabilizes the plane on the track at a low speed, then speeds the treadmill up, while the plane itself is actually moving nowhere, the treadmill was moving at a great speed meaning that if the speed were the same, the plane would be moving forward. The Jews are finally all going to die...
January 30, 200817 yr If the belt moves at 10 m/s and the plane moves at 10m/s then the plane will be moving forward because the wheels have almost nothing to do with the motion of the plane and if you would have watched the video you would understand that because when he stabilizes the plane on the track at a low speed, then speeds the treadmill up, while the plane itself is actually moving nowhere, the treadmill was moving at a great speed meaning that if the speed were the same, the plane would be moving forward. The Jews are finally all going to die... You don't need to explain it to him; he's banned. As for me, I definitely think the plane will take off.
January 30, 200817 yr You don't need to explain it to him; he's banned. As for me, I definitely think the plane will take off. He's most likely a troll who just makes accounts so he'll be back So: http://img441.imageshack.us/img441/5656/planeob6.jpg So if their speeds are to equal each other, then the plane would be moving forward, even when the plane is just acelerating
