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WHY aren't you moving forward? Explain to us exactly what force is keeping the engine from pulling the aircraft forward. That's the whole point, and you have repeatedly failed to explain this crucial bit of supporting information! And furthermore, in my scenario, the belt is not what is keeping the cart stationary. The belt is trying to move the cart BACKWARDS, not keep it stationary. The ROPE is the only thing keeping the cart stationary. And when the person pulls a little - just a little - harder on the rope, you have airspeed and headwind! That was my whole point, and you completely missed it! |
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And no one has taken away the wheels. And the conveyor belt won't stop the wheels from reducing friction. They will keep on doing that irregardless of how fast they go. Friction within the bearings will rise with speed. However, modern bearings are pretty good. A greased roller bearing just won't ever produce enough friction to overcome the thrust of any aircraft engine. At the worst we're talking about around 20 pounds of friction verse hundreds of pounds of thrust. By the time you've got enough friction in the bearings to overcome the thrust of an aircraft engine the bearing has long since melted and fallen apart. But that will never happen. The aircraft won't be on the conveyor belt long enough. It'll just roll right off it. |
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I agree wheels spin freely, so that is why, the conveyor belt would easily be able to keep the airplane from moving even with the engines spooling up. the airplane has to get the tires moving faster than the conveyor belt to move forward (and i know the tires spin freely and have absolutely no gearing or whatsoever and no bearing on moving the airplane forward other than they reduce friction and allow the plane to accelerate more quickly) as the engines spool up the convery goes faster and the airplane doesn't move. won't fly. I understand what you are trying to say, but it's not going to happen. If you put the airplane on the conveyor belt with the engines already running at full power and the conveyor belt is working against the forward motion of the airplane, do you still think it will take off??? |
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Stop. Stop. Stop. It can't. The conveyor can not keep the plane in the same spot. No conveyor on earth can keep an airplane stationary. Surely you know this. Truth table time: 1. A stationary airplane at full throttle cannot fly, if there is no air over the wings. TRUE 2. A conveyor has the ability to hold an airplane at full throttle stationary. FALSE Do you agree with #1 and #2? |
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OK, now we're getting somewhere.....You are saying that " the engines, just like your guy pulling the rope, spool up, but the conveyor keeps the cart in the same spot." This is the point everyone is trying to make to you. The amount of force the guy with the rope is having to exert to keep the cart in the same spot is minimal. If he wants, he can pull harder and actually pull the cart toward him (which in the plane scenario is like the engines pulling the plane forward in relation to the hangar on the side of the runway, and coincidentally, the air). As long as the thrust from the engines can be greater than the friction of the wheels, the engines can overcome that friction and result in forward airspeed....thus the plane can take off. At some point, even if the wheels were invincible, the friction of the wheel bearings will peak. That point will be less than the thrust capability of the engines, so they will always win the tug-o-war and pull the plane forward through the air. |
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No, clearly you do not see what we are trying to say. WHAT FORCE IS KEEPING THE PLANE FROM MOVING FORWARD? JUST TELL US! The wheels spinning freely is why the belt can NOT keep the plane stationary. Can't you see that? How can you see the facts and read them bass-ackwards? |
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I think you're getting confused... THE CONVEYOR BELT IS IRRELEVENT |
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then the conveyor belt is a moot point. there would be no need for a conveyor belt in the first place. all you are saying is that the engines have enough thrust to overcome a set speed on the conveyor. the conveyor isn't accelerating to keep the airplane from moving forward of its relative position. all you are saying is the airplane will have a much higher groundspeed than airspeed. |
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No. No. No. Because no conveyor on earth is cable of working against the forward motion of an airplane. If such a magical conveyor existed (it's not even possible to build one), then it would not take off. However, no such conveyor exists, and it is impossible even in theory for one to be constructed. |
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I don't get it . . . what's the difference between a conveyor belt and treadmill in terms of our experiment? |
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OMFG! He got it! Sniper7, the conveyor belt was added to the question to cause confusion - it has no affect on the planes movement whatsoever. |
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I'm not quite sure what you mean, but I'll just say again, to respond to the part in red, that for the conveyor belt to overcome the forward thrust of the propeller (and therefore keep the aircraft at 0 airspeed), the conveyor belt would have to utilize the small amount of friction in the wheels in a way that completely cancels out the enormous force of the engines. We're talking an ENORMOUS acceleration of the conveyor belt. As I have said before, in a split second the wheels would spin themselves out as they reached thousands of RPS. |
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Well . . . to be completely honest and accurate, it does have a very small effect. But not enough of one to bother taking into account for this experiment. |
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Yes, sorry. To correct myself, it has a negligible affect on the planes movement, nowhere near enough to prevent it from taking off. |
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but you are still on the ground. sure the wheels aren't needed in the air, but they are needed on the ground. ever see a 747 taxi with its gear up? didn't think so. needs the tires to reduce friction. the plane moves forward because the thrust is the power source...sure that easy to understand, but the reason it moves forward easily is due to the tires having a small coefficent of friction compared to the aluminum fuselage of the plane. the tires have to spin forward at a certain rate (if there is no wind whatsoever) in order for the plane to generate forward movement. the forward movement is read in airspeed. at a certain airspeed, the plane will take off. and the tires will be rotating at same groundspeed (no coveyor belt, plane at sea level on a standard day). the air over the wings generates the lift. more lbs of lift is created over the weight of the aircraft in lbs and off she goes into the air. if, in your scenario, there is no relative movement of the airplane at all, it won't fly. there is no headwind, the airplane has no forward motion. won't get off the ground. if your converyor belt sucks and allows the airplane to move foward, all you are doing is requiring more wheel rotations (which will blow the tires depending on their rating) If you have -10 knots of groundspeed from your conveyor and the airplane needs to rotate and 140 knots. the plane has to be doing 140 knots of airspeed. this translates into 150 knots of wheel speed AKA: groundspeed. on my airplane, 182 knots is max groundspeed for the wheels. above that, a very high chance of a blowout occurs. |
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Whew . . . is it over?
If so, sniper7, my hat's off to you (if I had a hat). You were a worthy adversary. Not for knowledge and logic, but for sheer persistance. |
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Is this it? Has the one lone hold out been converted? Have we finally reached a point where every person agrees that the plane will fly? If so, my life is complete. There is nothing left to do. I shall die a happy man.
And we did it without arguing over whether the wheel speed being referenced was tangential or angular. We've come a long way. The forum is getting smarter by the day. I can feel it. |
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The airplanes wheels would have to rotate in a forward direction in order for the entire airplane to move (it is still on the ground, not in the air). If the conveyor accelerates, the wheels move backwards even faster as the airplane is trying to move forward with the thrust of its engines. There is no relative forward motion and the plane won't fly. the tires just spin fast, the engines spin fast and blast a lot of air out the back that would be accelerating the airplane forward, but the conveyor is keeping it from moving forward at all. |
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I think it already needs repeating |
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*sigh* maybe it's not over. You have all the facts correct. I do not know how you are arriving at the conclusion that a conveyor belt could stop a plane with its engines on. Everything you pointed out goes against that claim! This has nothing to do with a sucky belt that can't stop a plane. This has to do with the coefficient of wheel drag vs. engine thrust. The belt only has wheel drag to work with, nothing else. You may be able to get the belt so fast that the wheels are in danger of shredding. Realistically, you wouldn't WANT to take off, because this would require an even faster wheel spin rate, which would tear them apart. But you COULD move forward if you didn't care if the wheels desintegrated. |
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Sorry about that. I was elated there for a moment. |
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The conveyor belt will not stop the plane. You can get the best damned conveyor belt in the world and it will not stop the plane from moving forward, it will only cause the wheels to spin faster. Read the big red part again. |
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Just say the plane flies, so I can work on the last hold out. This will all be over soon. |
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Correct...but the engines only have to generate an equivalent of 140 knots worth of thrust, not 150 because motion of the conveyor is adding a negligible amount of drag on the plane. whether the wheels are turning at 150 or 1500 knots groundspeed is of no consequence to the engines, they still only need to produce an equivalent of 140 knots of airspeed worth of thrust. We all realize that tires will fail, etc. however this is a physics exercise, not an exercise in actual mechanics of the equipment. |
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You, seriously, need to stop. Whether you are playing us all (which I highly suspect, because quite frankly, you are the first pilot to say it won't fly) or you have the cognitive ability of someone who should wear a helmet all the time. I hope for you and your passengers it's the former. |
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I just saw you live in CA, so everything I hear from you is now false... The tires have to rotate in at a faster speed than the conveyor belt. the plane is still on the ground. the plane is not in the air, is generating no lift whatsoever and is not going to fly. the wheelspeed will just increase. what you guys are saying is that the tires of an airplane don't spin as fast as the plane is moving through the air. you are flat out dead wrong in this situation. at sea level on a standard day. altitude and pressure and compressibility come into effect, but on a standard calm wind day at sea level, the tires have to rotate forward at the same speed as the plane is traveling through the air in order for the plane to lift off the ground. and I say moving through the air...that means a forward movement because there is no outside force creating a headwind. |
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No. No, no, no, and no. Also, no. Oh, my god, will I ever get through to you? The wheels are free-spinning. If you accelerate the conveyor belt, it will exert a very small backwards force on the plane, one that the plane's engine can easily overcome. The faster the acceleration, the greater the friction, and the harder the belt will pull backwards. But to pull backwards hard enough to keep a fully-powered-up plane stationary, AS I HAVE SAID SEVERAL TIMES BEFORE, the belt would have to accelerate incredibly fast, so fast that the wheels would spin themselves apart in a split second. Anything short of that, and the plane could move forward. |
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You're not a retard, and the plane doesn't take off. |
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Pretty please, answer this question...
Take a Saturn 5 rocket. Strap wheels to it. Place it on the TMC©. Ignite... Does the rocket move? |
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It's a little of both. If a magic conveyor existed that could acelerate to infinity, the plane would remain stationary. All I was trying to get across was that no conveyor ever devised (now or in the future) could keep an airplane still. If we're also going to argue that the wheels will blow up, then ya - the plane doesn't fly. But that misses the whole point of the excersise, as you pointed out. |
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*sigh* And you had it. The wheels are only going to rotate in one direction. Talking about them rotating forwards or backwards is just confusing you. How fast they rotate has nothing to do with the airplane taking off or not. What matters are the forces involved. The force of the engine is always going to overcome the force of friction of the bearings in the wheels. -Local |
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1 yes, 2 no
why not put the airplane on the conveyor with the engines already at full power and then say it isn't moving forward or backward. Even with the engine at idle, there is still forward thrust generated. just not enough to get the airplane to move. so if you put the plane on the conveyor with the engines already running at full power, and there is no forward movement, it won't fly, even though the wheels are hauling ass, the conveyor is hauling ass, there is no airflow and no lift, just a few tires ready to blow... |
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You are talking yourself in circles dude. You are not a pilot, and you have no grasp of physics. wheelspeed has nothing to do with engine thrust or airspeed....period...they are totally unrelated. You agreed earlier that this is true, and yet you continue to insist that the conveyor will hold the plane in place. You're just being an ass for the sake of being an ass. |
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Please explain how it will fly with no air flowing over the wings? |
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not converted at all. it won't fly. |
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OK . . . either you are a complete DEET DEE-DEE or you are a very, very skilled and determined troll. If you are the latter, it is time to give up, because you've carried this on long enough. If the former, I'm sorry, but perhaps someone here could recommend a good special school. To respond to your first paragraph: WHAT FORCE IS KEEPING THE PLANE FROM MOVING FORWARD? I've asked this many times, and you will not answer! This is key! Tell us! Yes, you are right, on a standard runway, the tires rotate at the same speed as the plane is traveling through the air. You are ABSOLUTELY FREAKIN' CORRECT! But we're not TALKING about a standard runway! We're talking about a goddern MOVING runway! Do you understand? On a moving runway, the airspeed will be DIFFERENT than the wheel speed! That still won't effect the AIRSPEED! The wheels have nothing to do with airspeed! They ONLY have to do with wheel speed! Airspeed depends on the power of the propeller! (unless brakes are applied) ARRRRRGH! |
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didn't get it, you are mistaken... |
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Every last thing you just wrote is true, were it possible for a conveyor to hold an airplane still. However on planet earth, no conveyor could hold an airplane still. |
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1. Read the whole thread. I'm busy answering this very question for sniper7. 2. Quick answer: It is impossible for a conveyor to hold an airplane stationary. It moves, it has air over the wings, and it flies - with wheels that turned REALLY fast before it worked up enough airspeed to take off. |
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Please explain why there would be no air flowing over the wings... |
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Is it because you think a conveyor could actually be devised, that was capable of holding an airplane at full throttle in one place? |
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Just in case it hasn't been mentioned in the pages I haven't read,... Ask your wife.!1!!11!! LOL |
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read the red part. the entire scenario is pointless. all you are saying is that it takes forward motion and forward wheel speed (whether 2x great or 3x greater or whatever) over the conveyor belts speed in order for the plane to reach sufficient forward speed to generate the lift required. Even the cars come into play on this then. a conveyor is moving backwards at 10 mph. the car accelerates to mph on the speedo. it is doing 10 mph through the air, 20 over the ground. same with the airplane. 10 knots backwards on the conveyor, 20 knots airspeed, the plane is moving forward at 10 knots of airspeed, 20 knots groundspeed. The origional scenario said the conveyor keeps the airplane from moving foward...so it won't fly |
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No you're just adding shit to it because it never said that... It said TMC© would match the wheel speed. Big difference. But I think you already knew that. |
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DING DING DING....close this thread. You misunderstood the original scenario because IT IS IMPOSSIBLE for the converyor to keep the plane from moving forward. That's the question the original scenario posed in the first place...."Can the conveyor keep the airplane from flying". The answer, of course, is no. You've been trying to answer the wrong question. |
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sure the wheels will rotate in a forward (counter-clockwise if looked at from left side of aircraft) motion. they will only rotate forward as the conveyor moves in a clockwise rotation. how fast they rotate does have something to do with it. if the conveyor is turning at the exact same speed as the wheels, the planes fuselage (connected to the wheels through the landing gear) will not move through the air. |
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Ladies and gentlemen of ARFcom, I have come to an alarming conclusion. Please remain calm as I explain.
There is no creature in existence, human or otherwise, that could possibly be as dense as this entity that we have encountered here in this thread. There is only one possibility - and believe me, I did not come to this conclusion lightly. This creature is, quite simply, not of this Earth - indeed, it is not even of this dimension! We are dealing with a kind of denseness that has never been encountered before. Ladies and gentlemen, this goes far, far beyond WTC truthers. We must rethink everything we thought we knew about denseness in order to come up with a defense strategy. As this is like nothing we have dealt with before, I do not know how we will fare. But let me say this: We MUST succeed! |
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