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Dude . . . dude . . . have you read ANYTHING we've been saying? Your whole premise is incorrect! Therefore your arguments are moot! Since you can't explain my simple explanation, I'll explain it another way. Let's say you're sitting on a shopping cart. The shopping cart is on a conveyor belt. The belt begins to move backwards. But someone ahead of you is holding onto you with a rope, keeping you from moving backwards. So now you're not moving, and the wheels are spinning as the belt rushes below you. It may be bumpy, but you're not moving. The only grip the belt has on your cart is the friction of the wheels. That's easy to fight against, since these wheels are high quality and well-lubricated. The belt is traveling at 50mph, but the person holding the rope isn't having a hard time keeping you stationary. Then the person in front of you holding the rope gives you a tug. You move forward! You now have a groundspeed of 1mph, and the wheels are spinning at 51mph. The person controlling the speed of the belt sees this and he speeds up the belt to stop you. As the conveyor belt speeds up and the wheels spin faster, the friction in the wheels increases and the person has to hold on harder. But now the conveyor belt is going at 100mph, and he can still hold on. He gives another tug, and you move forwards again! The conveyor belt operator sees this and accelerates to 200mph. But the wheels aren't made for those speeds, and they tear themselves apart, and you are killed as the cart flips over and you land face-down on the speeding rubber, which instantly skins and eviscerates you. Nice going, moron. |
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But, if the conveyor belt is running at a speed that keeps the aircraft at fixed position. ((look at my post above) for the relative to the building and you are a spectator on the other side of the moving conveyor belt runway) There would be no relative forward motion. The tires have to turn, but if the conveyor is moving at 100 mph and the wheels are moving at 100 mph with the engines at takeoff thrust, but there is no relative forward motion, the airplane won't fly. |
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Read that part in red. Stop RIGHT THERE. There is your problem. Stop, stop, stop. Alto! The conveyor CAN NOT keep the airplane in the same spot. It could if the airplane was powered by the wheels (like a car), but on an airplane, the wheels simply spin freely. If you placed a car in neutral, strapped a jet engine on top, placed it on a conveyor that was moving backwards at 1,000,000mph, the car would move forward. You agree with this, right? |
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Unbelievable. There is nothing to prevent the plane from moving forward. read the question again very slowly. It even states the plane "moves" movement creates air speed. |
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airplanes are not driven at all by the wheels. and no you would not have any speed compared to a DME. it measures distance and bearing and gives a speed. if the airplane isn't moving towards or away from the DME station (VOR-DME for example), there is no groundspeed. |
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Read my last post. |
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Ok IF the belt can keep the plane in the same place then no the plane wont take off. BUT the whole point is that the belt can't keep the airplane in the same place it just can't happen. So yes the way you're reading the question the plane will not take off....but in the real world where the rest of us live it would. |
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wait... wait wait wait.... say again-- you say you're a pilot... so you have no understanding of how an airplane flies OR navigates? WOW! |
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Well, that post certainly doesn't explain the solution. |
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No, of course not. Conveyor belts are magic. |
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AeroE - you're here! THANK GOD. Will you please explain to Sniper what you do for a living, and will you PLEASE explain to him why a conveyor can't hold a plane still? For the love of God, my head is going to explode.
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what does the speed of the wheels have to do with the ability of the engines to push against the air? As has been said MULTIPLE times already, the action of the treadmill on the plane is negated by the free-spinning wheels, leaving the engines to act on the air as if the plane were at zero knots airspeed and just starting their takeoff roll. Attach the plane to a big string and hang it from a hook so that it's not touching the ground at all. Now power up the engines. Does it move forward in relation to the hangar? YES. why? because there is no friction holding the plane in place. the wheels of the plane achieve the same effect as hanging the plane by the hook by neutralizing the rearward motion of the treadmill. The net effect is that the free spinning wheels allow the engines to push against the air behind them and move the plane forward in relation to the hangar (the wheel speed will be treadmill speed + airplane speed relative to the hangar.) |
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I wasn't offended, I'm sorry if I made it sound like I was. I actually get a kick out of these threads. The arguments some of these goofballs come up with are hilarious. |
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yes I watched the video, and the plane had forward motion which completely negates anything in the conveyor situation. In the conveyor situation, the aircraft has no relative forward motion compared on an object off of the conveyor. that means there is no airpseed. no airspeed = no flight simple as that. And if the groundspeed is such a big factor, then forget ground speed all together. because what you are really saying is that an airplane will takeoff with the engines pushed to full power with no relative motion. Go to the airport and watch small airplanes do their runups with the brakes on. do you see them lift off the ground? no you say? because they have no airspeed. if they aren't getting any wind over the wings, they won't fly. |
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Are you fucking high? Does the conveyor somehow cause it's GPS coordinates to change, even though the object is, according to you, stationary? |
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So answer me this one question.....WHY is there no headwind?[/quote] because the airplane is stationary compared to a fixed object off the conveyor. that means it has no relative motion. there is no outside source of headwind, that means the plane won't fly. the airplane has no forward motion at all because the conveyor belt is working in the opposite direction at the same speed. |
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that's because their engine thrust is being overcome by the friction of the braked wheels. the forces are negated. the force of the treadmill is negated by the movement of the wheels, leaving the force generated by the engines to act on the air around it and push the plane forward. |
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For the love of all that is holy... You just ignored everything I wrote. I'm...speechless. |
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But you are talking about a VERY specific situation, where the forward power of the engines equals the friction in the wheels, which holds the plane at 0 groundspeed on a moving belt. We're talking about if the plane COULD take off, not if it's possible to hold a plane stationary on a moving belt. |
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There is one concept that you are seriously failing to see: The movement of the conveyor is dependent upon the speed of the aircrafy. In order for the conveyor to "match the speed" of the plane, the plane must be moving. It will not appear stationary - it will be moving forward at X speed, but the wheels will be spinning at 2X speed. How hard is this to understand? The conveyor does NOT MOVE unless the plane moves.. |
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maybe so with your bearing, but your r/c plane will still not fly unless it has a greater than 1:1 thrust to lift ratio. if the engine is running at full power and the conveyor is working at the exact same speed, the plane has no relative motion to something off the conveyor. and it has no headwind generated by any other source. the plane is stationary even with the wheels spinning because the conveyor is keeping it still. won't fly. |
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EXACTLY!!!! The planes don't take off because the brakes are INCREASING the friction between the ground and the airframe to a level greater than the engines ability to create lift. Take the brakes off and it doesn't matter what the speed of the wheels is, the remaining friction is small enough that the engine will be able to push the plane forward through the air, generating airspeed and allowing the plane to achieve takeoff airspeed. |
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Nope, I ain't sayin' one way or t'other. I'm busy lining up property for the Helga and the survivors. When I had a real job, I designed stuff to kill commies, socialists, terrorists, and other ne'er do wells. Now I'm reduced to grinding through 747-8 ribs and trying to understand how the fuck anyone could think CATIA is worth a fuck, and how the hell BCA ever built an airplane without a discernible drawing tree. Fundamental crap like that. The first thread should be out of the black hole by now. I'll check to see where the last one is, be right back - |
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What's your source for the fixed object off the belt? Where are you getting your version of the question? It doesn't match any version I've read yet. Again, here's the question. It has nothing about maintaining zero movement in relation to a fixed object off the belt.
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so then the entire scenario is out of the question because the conveyor did not keep the airplane from moving forward along the range of the conveyor belt. The whole thing would be scrapped then. In the scenario, the conveyor keeps the airplane from having any forward motion (it stays in the exact same spot even though the wheels and converyor are turning). you aren't talking about the same thing. live with it |
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You understand that airplanes are not driven by thier wheels, but still suppose that the airplane will not move off the belt. Why? What is keeping the airplane on the belt? Put another way, what counter acts the force of the engine? Lets look at an f15 again. Lets say one engine isn't running today, to make it even more apparent, and the pilot wants to show off what hot shit the Eagle is to all those little Viper drivers. So he throttles that one engine right up to full afterburner, cranking out all 15,000 lbs of force he can. Think about 15,000 pounds of force. Thats 7 and a half tons of force. Thats more then 2 elephants. In order to hold that aircraft in place you need to exert that 15,000 lbs of force in the other direction. So where does all that counteracting force come from, and how do you apply it to the aircraft? Now, I'll accept that this is a magical conveyor belt, and it could produce that much force. But how does it act on that aircraft? Through it's three wheels, of course. Each wheel probably rests on several bearings, which ride on a shaft or two. Lets suppose that the bearings are just so-so. With out the math involved, I figure that all three wheels together might produce a retarding force/friction of about 10 pounds (I'm not including static friction, which would be quite a bit higher). So thats 15,000 lbs minus 10, or 14,990 net pounds of thrust acting on the air frame. So, how does the airplane not move? -Local |
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O M F G ! You can't be this dumb. Have you not read one word we've been writing for the last two or three pages? The conveyor belt CANNOT work against the plane, except as far as the tiny amount of friction in the wheels will allow! You are living in a fantasy world! Come back to our world! Things make much more sense here! All the conveyor belt does is spin the wheels. In normal circumstances, when the plane throttles up and begins to speed down the runway, what are the wheels doing? Spinning! The aircraft is MADE to move forward as the wheels are spinning backwards! |
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No . . . you see, I live on a planet called Earth. In my world, your scenario is impossible. I believe that it is a waste of time to wonder if something impossible is possible. Now, your scenario IS possible if the machines are specifically made for this sort of thing. For example, wheels that are made to have a lot of friction, so that the conveyor belt actually has something to work with. As the speed goes up, the wheels will produce more and more friction. Eventually, at a certain speed, and assuming the wheels aren't spinning fast enough to rip apart, the engine will not have enough power to fight against the friction, and then any more speed you add to the belt will make the vehicle move backwards. But a plane's wheels, assuming they are in OK condition, simply do not have enough friction for this to ever work. Their wheels would self-destruct before the friction equaled the engine's thrust. |
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in the scenario, the airplane, even after putting in all its power has no forward motion (if the converyor keeps the plane in the same relative spot. sorry man, but not trolling and speaking of dense, take a look at your avatar, then look in the mirror. the plane won't fly if there is no relative forward motion and there is no outside force generating a headwind |
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really? and what exactly do you do for a living because I hope it is nothing more than picking up dog shit in the neighborhood park because thats about the only thing you have a clue about. |
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You keep refusing to answer the question posed to you over and over and over again Sniper. HOW does the belt keep the plane in place....Answer that question...HOW? |
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You are pulling the "no relative motion" out of your ass. The conveyor can not put enough rearward force on the plane, via the interaction with the planes free-spinning wheels, to keep the plane form moving. Your statement that a plane can not fly without air flow over the wing is correct. Your statement that the conveyor will keep the plane form moving forward, the basis for your entire disagreement, is flat-out false. |
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Sniper- No conveyor belt, however magical or however good the control system, could keep a typical airplane in place. The amount of force it would have to exert through the airplanes wheels is simply too high. The wheels would have to be spun at hundreds of thousands of rpm, perhaps higher, before the belt could actually counteract the thrust of even a small engine. Long before that the bearings or tires would have failed. And that makes sense. The whole goal of the wheels and bearing is to reduce as far as possible the friction between the ground and airplane. The fact is that there is no way to hold that airplane in place by spinning it's tires. -Local |
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Please answer the following question...
Take a Saturn 5 rocket. Strap wheels to it. Place it on the TMC©. Ignite... Does the rocket move? |
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One more time, before I give up and fully realize that I'm being played here, as part of a well executed joke: In what world can a conveyor keep an airplane still? How fast would a conveyor have to move backwards to hold even a Cessna in one place, when it's at full throttle? |
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Really? I know the plane takes off. Your insults are meaningless because you refuse to see reality. So I reiterate. Stop flying so you don't kill yourself or others. |
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AHAHAHAHAHAHAHA!!!!!!! It makes sense! If free-spinning wheels can hold a plane back, it could certainly hold back a Saturn V! My god, we may be entering a whole new realm of physics, all thanks to sniper7! |
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www.ar15.com/forums/topic.html?b=1&f=5&t=626727 www.ar15.com/forums/topic.html?b=1&f=5&t=635149 www.ar15.com/forums/topic.html?b=1&f=5&t=634624 I couldn't find the first thread, but that's not necessary anyway. |
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very true, you can't get the conveyor belt to finght against the engines. but, then let me ask you, why the fuck then do airplanes have fucking wheels in the first place? they obviously don't need them. why the hell don't delta and untied put conveyor belts on the fucking ramps? I'll tell you why, because they are smarter than all of you who think the plane will actually fly. the engines create the thrust, the wheels allow the aircraft to roll. that rolling forward motion is generated by the thrust of the engines displacing air (doesn't matter if it is turbine or prop). the air that is displaced is compressed and exerted backwards pushing the airplane forward. the forward motionis transmitter through the air by the engines, but made easier (friction) by the wheels. a rolling object is much easier to move that an airplane without landing gear (watch a geared up airplane try to taxi) and see how far he gets with all the fucking power pushing all the air....not going to happen. you have to have the tires to reduce frition so you can gain airspeed so you can get air over the wings so you can fly. |
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Wow, that's awesome! Someone who has fallen in Retard Quicksand getting all haughty at someone who mentions maybe he should just swim out of it. ETA: DANGIT! I FORGOT THAT I WAS TRYING NOT TO TAG THIS THREAD! CURSE YOU GD! |
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You all managed to do it again. The worst part is, a lot of you are the same people as in the other nine thousand threads. I hope you have your posts saved in a file, please tell me you don't spend your time doing this again and again.
There is a special room in hell where all people do is discuss this question. All of you that choose to do this in the mortal world are a special breed of fucked up. btw- the fucking plane flies! |
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Because they figured power-sliding into the terminal wasn't a good idea.
Next stupid questions. |
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Excellent post, and I might as well have written it myself. You actually get it, but somehow conclude that a plane with free spinning wheels is unable to move forward on a conveyor. Man, you're like --> <-- this close to getting it. |
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And all of this, while technically correct, doesn't explain how you think the belt can prevent the airplane from achieving forward airspeed, regardless of the speed of the belt or the wheels. |
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I really can't believe I'm arguing about this. You are either very blind or incredibly stupid. I'm NOT kidding, and I'm not being rude. I'm being factual. Your post has nothing to do with my post. I can't even respond. You have no clue what we are saying, but you THINK you do. |
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I'm off to make a thread pic just for this thread... brb....
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same thing an airplane would do. the tires would blow, you wouldn't fly and more than likely everyone would be killed in the crash and post crash fire. nice going moron...you told me absolutely nothing. the engines, just like your guy pulling the rope, spool up, but the conveyor keeps the cart in the same spot. if the converyor keeps the airplane in the same spot, it won't fly. the wheels can turn 200 mph, but you have no airspeed because you are not moving foward. |
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When a dozen people with experience are telling you that you are a retard, a wise person would listen. Then again, most retards aren't wise.
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I think everyone is getting confused here.
Conveyor belt, not a tread mill. |
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