Macho Nacho Posted September 29, 2007 Share Posted September 29, 2007 Here is my take. Quote Link to comment Share on other sites More sharing options...
Gilbert Posted October 3, 2007 Share Posted October 3, 2007 now, let it sit on its wheels. the only difference is the wheels rotate, which has nothing whatsoever to do with the plane's forward motion. Geez. I gonna go take some pictures of my speakers. Ah yes, I forgot all about the ole frictionless wheel invention. Who was that again that invent those? I think it was PT Bar...something or other. ;-) , HOWEVER, I would like to see pictures of your speakers. Mr. Macho Nacho, THAT! is what I call some serious friction..... Just imagine, if that pilot could have landed on a conveyor belt supported with frictionless pullies/wheels, then all emergency landings would be a thing of the past. Quote Link to comment Share on other sites More sharing options...
Gilbert Posted October 3, 2007 Share Posted October 3, 2007 Paul, You have way too much time on your hands Geeeezus, if that's not the pot calling the kettle black. [] []..... You write freaking essays when you post and now this, GEEEEZOUS! Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted October 3, 2007 Share Posted October 3, 2007 yes. have a blessed day, roy Quote Link to comment Share on other sites More sharing options...
sputnik Posted October 3, 2007 Share Posted October 3, 2007 Ah yes, I forgot all about the ole frictionless wheel invention. Who was that again that invent those? It think it was PT Bar...something or other. ;-) , ....... Gilbert, are you still in denial?? The system doesn't have to be frictionless for the plane to take off. [ap] Quote Link to comment Share on other sites More sharing options...
Gilbert Posted October 3, 2007 Share Posted October 3, 2007 Ah yes, I forgot all about the ole frictionless wheel invention. Who was that again that invent those? It think it was PT Bar...something or other. ;-) , ....... Gilbert, are you still in denial?? The system doesn't have to be frictionless for the plane to take off. [ap] I just love you to death sputnik, and I'm so sorry ole boy, but friction is absolutely required to act at the bottom surface of the wing in order for take-off to occur. This is fundamental on a fixed wing & rotor wing aircraft. I know that's not what you meant, but it's a great starting point for my initial response :-), LMFAO Quote Link to comment Share on other sites More sharing options...
sputnik Posted October 3, 2007 Share Posted October 3, 2007 Gilbert, it looks like the hook is set and you're taking line. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted October 3, 2007 Share Posted October 3, 2007 Ah yes, I forgot all about the ole frictionless wheel invention. Who was that again that invent those? It think it was PT Bar...something or other. ;-) , ....... Gilbert, are you still in denial?? The system doesn't have to be frictionless for the plane to take off. [ap] I just love you to death sputnik, and I'm so sorry ole boy, but friction is absolutely required to act at the bottom surface of the wing in order for take-off to occur. This is fundamental on a fixed wing & rotor wing aircraft. I know that's not what you meant, but it's a great starting point for my initial response :-), LMFAO I thought it was lift created by high and low pressure? Yes friction has some play in there but Bernoulli? Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted October 4, 2007 Share Posted October 4, 2007 now, let it sit on its wheels. the only difference is the wheels rotate, which has nothing whatsoever to do with the plane's forward motion. Geez. I gonna go take some pictures of my speakers. Ah yes, I forgot all about the ole frictionless wheel invention. Who was that again that invent those? I think it was PT Bar...something or other. ;-) , HOWEVER, I would like to see pictures of your speakers. Mr. Macho Nacho, THAT! is what I call some serious friction..... Just imagine, if that pilot could have landed on a conveyor belt supported with frictionless pullies/wheels, then all emergency landings would be a thing of the past. Well, yes, of course, in the real world there will be bearing friction, the wheels don't rotate completely freely, and there is the initial inertia resisting the rotation of the wheels... exactly how those forces get transferred to the airframe, and to what degree, is math that is beyond me right now, but it does exist, and clearly if the belt is moving fast enough beneath the plane the friction resisting the rotation of the wheels is going to overcome whatever thrust the engine is capable of generating and the plane will be dragged backwards against the thrust of the engine. My feeling is the belt would have to be moving P.D.F. (uh, pretty dam fast) for that to happen, but it would happen, eventually, no matter how powerful the engines are. but I think that's kind of missing the point. As a thought problem, the point is that the airplane's forward motion is due to the action of the engines on the air, and not related to the contact between the wheels and the ground. If the wheels were frictionless the plane would take off no matter what the belt does... unless the belt is moving so fast that the boundry layer of air at its surface is pulled backwards so fast that it... uh, screws everything up. And to everyone who keeps harping on Bernoulli (?Spell?) as the reason planes fly, it's not that complicated. Planes fly because the wing pushes the air down. Lift is a force acting against gravity. Force is mass times acceleration. The lift force must be offset by an equal and opposite force. That opposite force is the mass of air being accelerated downward. Whether that downward acceleration happens because of the Bernoulli principle, the curve of the wing, the angle of attack or whatever is not really important. You could fly a plane using a (very strong) sheet of flat plywood if you had sufficient power by setting the proper angle of attack. If the Bernoulli principle was only thing going on, no plane could fly upside down unless it could change the shape of the airfoil. This immence mass of air accelerating downwards is easiest to experience if you stand close to a rotaty winged aircraft when it takes off. It'll about knock you over. really cool. Quote Link to comment Share on other sites More sharing options...
maxg Posted October 4, 2007 Share Posted October 4, 2007 Paul, You have way too much time on your hands Geeeezus, if that's not the pot calling the kettle black. [] []..... You write freaking essays when you post and now this, GEEEEZOUS! Doesnt take that long - I type at 75 wpm. Mavis Beacon typing tutor - what a tool that was. In 2 days I learned to touch type and never looked back. I wonder if it stil exists? I used it back in the day of DOS and Wordperfect. Quote Link to comment Share on other sites More sharing options...
Champagne taste beer budget Posted October 4, 2007 Share Posted October 4, 2007 Rather than suggest everyone read the whole thread for the "Proper" answer, I recommend one need simply read the first page of this thread and pay attention to what is said. The correct answer, and its explaination, lies within that first page. And yes, Max, you can be long winded, but I generally like the results when you are. 75 wpm, eh? Impressive for someone that doesn't type for a living. Quote Link to comment Share on other sites More sharing options...
Gilbert Posted October 4, 2007 Share Posted October 4, 2007 I thought it was lift created by high and low pressure? Yes friction has some play in there but Bernoulli? This is true, lift is the net result created between different pressures acting on the foil or wing or rotor blade. Another way of putting it would be to say that there exists a higher pressure acting at the bottom of the foil relative to the pressure that acts across its upper surface.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> It is common for people to only think of friction as applying the breaks, but there are other ways of considering the force of friction. When you stick your hand out of a moving cars window, do you not feel a wind induced force acting on it. When you feel this wind acting across the surface of your hand, do you consider the texture of the skin on your hand (however smooth) as offering some type of frictional resistance to the flow of wind across it. If your car was infinitely fast do you think your hand would get a little warm from the friction of wind flowing over the surface of your skin? If no, then why are there specially designed ceramic tiles across the leading surfaces of the space shuttle. What causes these tiles on the space shuttle to heat up? Could it be wind friction as it enters the earths atmosphere? Does Einsteins theory of relative motion apply to all moving objects? Like say a moving jet aircraft traveling along a moving runway surface? What would happen to the jets taking-off atop the deck of an aircraft carrier if the ship was to suddenly have the ability to travel in the opposite direction, maintaining a speed equal to that of the jet aircraft? Would the jet lift-off anyway, or would it shoot off the bow and into the water? Hmmmm, food for thought, maybe? ZZZZZZZZZzzzzzzzzzzzzzzzzzzzzzzzzzzz, that's the sound of sputniks reel drag being wheeled out at an uncounciously fast rate of speed. [] Quote Link to comment Share on other sites More sharing options...
Gilbert Posted October 4, 2007 Share Posted October 4, 2007 Paul, You have way too much time on your hands Geeeezus, if that's not the pot calling the kettle black. [] []..... You write freaking essays when you post and now this, GEEEEZOUS! Doesnt take that long - I type at 75 wpm. Mavis Beacon typing tutor - what a tool that was. In 2 days I learned to touch type and never looked back. I wonder if it stil exists? I used it back in the day of DOS and Wordperfect. I used a program called Typing Tutor. Also with a DOS basd machine, and I still love Wordperfect. It beats the poopoo out of MS Word. Now howabout a nice octopus sandwich. Quote Link to comment Share on other sites More sharing options...
maxg Posted October 5, 2007 Share Posted October 5, 2007 "Does Einsteins theory of relative motion apply to all moving objects? Like say a moving jet aircraft traveling along a moving runway surface? What would happen to the jets taking-off atop the deck of an aircraft carrier if the ship was to suddenly have the ability to travel in the opposite direction, maintaining a speed equal to that of the jet aircraft? Would the jet lift-off anyway, or would it shoot off the bow and into the water? Hmmmm, food for thought, maybe?" Er....no. the ship is merely acting like the conveyor belt in the original problem. Ignoring the issues of the ship bouncing around on the water and upsetting the aircraft's balance as it takes off, it will still take off as normal with the wheels merely turning at the sum of the speeds of the aircraft and the ship. Basically the engines of the plane are not acting against the ship itself (as the powered wheels for a car would) but against the air. Quote Link to comment Share on other sites More sharing options...
mas Posted October 5, 2007 Share Posted October 5, 2007 "Does Einsteins theory of relative motion apply to all moving objects? Like say a moving jet aircraft traveling along a moving runway surface? What would happen to the jets taking-off atop the deck of an aircraft carrier if the ship was to suddenly have the ability to travel in the opposite direction, maintaining a speed equal to that of the jet aircraft? Would the jet lift-off anyway, or would it shoot off the bow and into the water? Hmmmm, food for thought, maybe?" Er....no. the ship is merely acting like the conveyor belt in the original problem. Ignoring the issues of the ship bouncing around on the water and upsetting the aircraft's balance as it takes off, it will still take off as normal with the wheels merely turning at the sum of the speeds of the aircraft and the ship. Basically the engines of the plane are not acting against the ship itself (as the powered wheels for a car would) but against the air. ...To expand the focus still further of those who are still hung up with the conveyor, a red herring... For those who want to get caught up with thinking about relative motion, you might want to shift your awareness to a larger context of relative motion, as the plane begins on a planet called Earth which is traveling at a velocity of ~29.8 km/sec in orbit around the sun and a rotational velocity of ~.47 km/sec. While many are getting caught up with relatively trivial issues of 'low level' relative motion, stop and think as to whether any plane can fly relative to the earth's motion...and how do they do it even if they are or are not taking off in a travel path opposite the motion of the earth..... The conveyor quickly becomes relatively trivial. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted October 5, 2007 Share Posted October 5, 2007 I thought it was lift created by high and low pressure? Yes friction has some play in there but Bernoulli? This is true, lift is the net result created between different pressures acting on the foil or wing or rotor blade. Another way of putting it would be to say that there exists a higher pressure acting at the bottom of the foil relative to the pressure that acts across its upper surface. uhh..... low pressure creates lift.... the high pressure is created when the air above the wing goes faster than the air below the wing... It is common for people to only think of friction as applying the breaks, but there are other ways of considering the force of friction. When you stick your hand out of a moving cars window, do you not feel a wind induced force acting on it. When you feel this wind acting across the surface of your hand, do you consider the texture of the skin on your hand (however smooth) as offering some type of frictional resistance to the flow of wind across it. If your car was infinitely fast do you think your hand would get a little warm from the friction of wind flowing over the surface of your skin? how fast are we talking about, friction is exponential....... even if your car can go say 200 mph, the likelyhood that friction heats up anything is nil versus the likelyhood that the air will actually remove any heat.... when you start to get faster than the speed of sound, the friction increases rapidly. If no, then why are there specially designed ceramic tiles across the leading surfaces of the space shuttle. What causes these tiles on the space shuttle to heat up? Could it be wind friction as it enters the earths atmosphere? its air friction..... but its more like when they try to come back from orbit at around 14000 mph, its more akin to say jumping off a 30 story building into water..... at that point, whether liquid or solid both will kill. Also the space shuttle or spacecrafts more or less come in the pattern back to earth that gives the greatest air friction since there is no other way to slow the vehicle down... the spaceship has no engine to maneuver in earth, its a billion dollar glider.... Does Einsteins theory of relative motion apply to all moving objects? Like say a moving jet aircraft traveling along a moving runway surface? What would happen to the jets taking-off atop the deck of an aircraft carrier if the ship was to suddenly have the ability to travel in the opposite direction, maintaining a speed equal to that of the jet aircraft? Would the jet lift-off anyway, or would it shoot off the bow and into the water? Hmmmm, food for thought, maybe? well speed is technically how fast you are relative to whatever you want to do...... sound of speed is the only thing not relative.... speed always is a constant speed (after determining air density, temperature, humidity, etc) Say you were on a train going 100 mph, and you start running at 10 mph.... are you going 110 mph or 10 mph? the answer is 10 mph relative to the train and 110 mph relative to say a train mile post. ZZZZZZZZZzzzzzzzzzzzzzzzzzzzzzzzzzzz, that's the sound of sputniks reel drag being wheeled out at an uncounciously fast rate of speed. [] Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted January 16, 2008 Share Posted January 16, 2008 tonite, 9pm eastern on discovery i think. mythbusters, i think. will a plane take off from a moving conveyor........ In Christ, because of God's grace, roy Quote Link to comment Share on other sites More sharing options...
IndyKlipschFan Posted January 16, 2008 Share Posted January 16, 2008 wow so we will find out... very cool! Quote Link to comment Share on other sites More sharing options...
dkp Posted January 16, 2008 Share Posted January 16, 2008 tonite, 9pm eastern on discovery i think. mythbusters, i think. will a plane take off from a moving conveyor........ In Christ, because of God's grace, roy Roy-got a link? I couldn't find it on their website. Quote Link to comment Share on other sites More sharing options...
bodcaw boy Posted January 16, 2008 Share Posted January 16, 2008 i saw a commerical on tv last night. in Christ, because of God's grace, roy Quote Link to comment Share on other sites More sharing options...
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