It's like this: You are standing on a skateboard on a long treadmill. It has long handrail next to it. You start pulling yourself forward with the handrail (like plane "pulls" itself forward with air). The treadmill starts moving at same speed at the opposite direction but it doesn't have any affect in your forward movement because you are UNCOUPLED from the treadmill by the wheels of the skateboard (just as a plane is by its wheels).
You walk on treadmill and your "speed" is matched by the treadmill you will of course stay stationary relative to the surroundings. If planes speed is matched by treadmill it means the plane is actually moving forward (relative to surroundings) at certain speed and the treadmill with same speed at opposite direction. (Meaning planes speed relative to treadmill surface is double its speed relative to surroundings.) Plane can only regulate its speed relative to air and is UNCOUPLED from treadmill
I see why people have a problem with this. It's sort of a trick question because the real core question of it is: WILL THE PLANE MOVE FORWARD OR NOT? Most people intuition says NO because we are used to transportation like walking and cars which "push" from ground to move forward. Then people think the problem of the question is will the plane fly if it's stationary relative to air and then the answer would of course be NO. But it WILL move forward because it pushes the AIR to move.
Well done, you've proved that bad wheel bearings have high friction. Do this with a real plane with real wheels and you'd have to move the belt at hundreds of miles an hour to stop it. In fact the tires would probably burst from overheating before drag from the wheel bearings became significant.
I think the problem is with this debate is that when people say "a plan can take off using a treadmill" there thinking in the sense that if a plain needs to get to say 120mph, and you take a treadmill to 120 mph, that it will be able to take off, and of course this is not the case because there is no lift, however since the engine powers the jets or whatever type of plane your using is, and not the wheels, it won't affect the plains ability to take off. But it still needs lift.
ok this is like walking on the moving sidewalks at airports if you walk at the EXACT same speed against the treadmill then you will be moving nowhere RELATIVE to the non moving part such as the floor, same with a plane if its not moving faster than the floor there is no air going over the wings and therefore NO LIFT WHICH MEANS NO TAKEOFF
@11cookeaw1 well of course you CAN takeoff from a treadmill whatever speed its going backwards is the extra you need to compensate for, BUT IF THE SPEEDS ARE EXACTLY THE SAME NO AIR GOES OVER THE WING = NO LIFT = NO TAKEOFF
@TheIceychill2 They both go at the plane's take off speed, there is simply no way the treadmill can hold the plane back at that speed, the plane will move and take off. The treadmill's friction will have similar effects on the air as the plane... Anyway, the plane's engines will push air backwards at high speeds.
The earth is a giant runway. Hopefully you can take off or else we would be in deep trouble. If we could in fact take planes off a treadmill then we would never need long runways again. The problem was if a plane can take off when the wheels match the speed of the conveyor belt. Video here shows plane probably with a front propeller (cant see it) that provides just enough air movement for the wings to generate lift. Modern aircraft push rather than pull to generate lift.
This is the Physics For Dummies version of this thought problem. It is not the original version of it. In the original version the speed of the treadmill matches the speed of the wheels. In the version shown here the speed of the wheels is greater. The original is tougher but there is a force that will hold it in place. The original version means that the belt will accelerate. The changing rotational inertia of the wheels creates a back force. If belt accelerates fast enough it will work..
@subductionzone Rotational inertia stopping a plane's mass that is orders of magnitude greater than the wheels mass. Your logic is flawed. In this version here the speed of the wheels matches the speed of the treadmill...see, plane not moving anywhere....then I accelerate the treadmill and it has no effect.
Do the mathematics behind it....you will see. Acceleration is not magic. Talk about acceleration...look at a plane landing. In your concept the plane would come to an instant stop.
@neodocneodoc I, and others have done the math. A personage no less than Cecil Adams of The Straight Dope has admitted that this can theoretically be done if the acceleration is great enough in a revisit to this problem. It does take a very high rate of acceleration, for a typical jet air liner we have calculated examples and found it would require 50 to 100 g's to keep say a 737 in place. By the way, if you Google search enough you will find that the "matches wheel speed" is the oldest versi
@subductionzone did you take into account the friction between the tire and the runway? So you're trying to tell me that an instantaneous force of 100G's will still allow the tires to grip? If tires were that good nothing would ever skid. Think about it. The rotational inertia of the wheel would resist this large acceleration and the tire would just skid...i.e. like skis on snow.
@neodocneodoc Yes we did. There are a few planes that could produce a high enough thrust to cause the plane's tires to skid, high power fighter jets or acrobatic planes. But the vast majority would not break lose. And yes, if the plane breaks free it is able to take off. Obviously there are no 50 to 100 g treadmills out there, or wheel bearings, tires, or a belt that could stand up to the sort of speeds and heat that would arise from this. But it can be done, as a thought problem.
@subductionzone my point was not that whether the plane's force could make the tires slip...it was that if you applied a substantial acceleration to the treadmill, the rotational inertia would 'want to' hold the wheel still. That 100G's that you are talking about would have to be transmitted to the wheel without slippage; if you have slippage, your point is moot. If it was a geartrain, another question, but you are talking about rubber on asphalt.
@neodocneodoc Remember you are only accelerating the wheels, not the whole plane. When a plane lands its wheels, very temporarily, accelerate at an even higher rate. That creates a noticeable jerk, that is before the brakes are applied. The force that the wheels can withstand can be calculated by using the static friction of the wheels on asphalt with the weight of the plane over them, traction and static friction are very closely related.
@subductionzone 99% of cases have the wording saying the belt matches the plane's speed not the wheels. I can't even find an exception. But more importantly, the thought experiment very obviously is testing whether a treadmill can stick a plane in place in the SAME WAY it sticks a person or car, otherwise it would HAVE to ask "how could a treadmill keep an accelerating plane stationary relative to the air" Why? Tracking wheels would be STUPID because the plane could be on skis! No tracking!
@nerfmyaccount It is higher now that the Mythbusters, who have a huge web following did their show, but the original version had the speed of the wheels matching the speed of the treadmill. Or perhaps I should say the oldest known version. And your claim that tracking the speed of the wheels is "STUPID" is just because you don't like that version of this problem.
The version you tested is high school physics at best. The original version takes more knowledge. And is more interestin
@nerfmyaccount Reply number 2. And your skis statement is incredibly inane. It is in the wording of the original version that the plane has wheels.
But you seem to understand one thing. If the plane was on skis, ideally it would not matter if the belt was accelerating or not. It would still take off.
@subductionzone that's a dumb and unlikely interpretation of the original problem sorry. let's track the wheels for no reason when we could just as easily track the wings and accelerate the treadmill to whatever necessary keep them relative to the air regardless of what connects the plane to the belt (wheels or skis) maybe the math is high school physics but the logic of the question is clearly above you. better luck next time.
@nerfmyaccount How is the interpretation that speed is to be measured at the wheels a "dumb interpretation"? I have gone over this with a person who is fluent in Russian, born there, and was an undergrad in physics. The wording of the original version is what it is. Again, your version is extremely easy to understand. A ninth grader should be able to get it. The original version is a bit trickier, and that is what makes it a better brain teaser. It takes a bit more physics to get it.
@nerfmyaccount You seem to be overly fond of your rather simplistic test. A analysis of forces on the plane would clearly show that it could fly with your preferred version. Again, ninth grade physics at best. In fact your version asks basically if a plane moves forward at its take off speed can it take off? Talk about a dumb and pointless question. Now the version I like is a bit pointless too, by definition the plane sits in place. It also asks if there is a force on the plane. There is
@subductionzone The point of the question is not complex physics but being able to override intuition to engage critical thought and realize that our personal experiences shape our macro interpretations of the world. We've walked on treadmills. We exercise on them. We use them at airports. We go up escalators. We've seen cars tested on them to stress the engine. The natural conclusion is to assume planes will stick on them, the test is to jump start your brain to break the intuition.
@subductionzone yes for some it is a simple and trivial problem. But for most people the complexity is NOT the physics but the intuition. If you think the average person views the world through a proper objective lens then I want to trade worlds with you. The question (as popularized all over the internet) DOES ask "can a plane take off with it's takeoff airspeed" but the hard part is getting people to realize that's what it's asking! If you think it's easy, find someone on the street and ask
@nerfmyaccount You very well may be right about the average person's perception. But this originally arose at a place where hopefully the students were intelligent enough to get the answer. Yes, I have seen many people get even your version of the problem wrong. An in reply to your previous post the physics is not all that complex. A first year physics major should be able to understand the forces involved.
I guess the version you use could depend on your audience.
A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
@neodocneodoc Hey clownballs, try reading what I said. I never stated the runway had to be any longer. I said the runway would need to be the proper length to gain airspeed to take off. So, using my example of a 747 if it was trying to take off from a treadmill.. the treadmill would need to be 6500 to 7500ft in length. Get it clueless? Using another example; If your lame ass model plane needed 10ft on the ground to take off, it would need a 10ft treadmill to take off. Pay attention class.
This is just a moving surface. Once overcoming surface friction, thrust does whatever it wants, it doesn't create a special airflow allowable for lift!
I'll repost my last comment: A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
And at 10mph it moved forward at about 15-20 mph relative to the treadmill speed. A speed I doubt that plane would be able to match on its own. Treadmill has no effect. Great video!
It would be cool if you cold somehow do a video demonstrating air speed over ground speed. Showing a plane take off at a very low gs or even flying backwards, it would be awesome (if you could find an environments that you could easily film).
why the fuck is everyone wasting time bitching about science? he mad the vid thank him then fuck off... someone makes a video to entertain you and you hop on their nuts telling them everything you disagree with? get a life faggots anyways i found this vid from watching fat chicks fall off tread mills so you can understand my little interest in the video itself but anyway this would be why i dont read youtube comments their always fucking retarded
treadmill should have adaptive speed - which means plane speed should be 0 (zero) while wheels contact belt. Wheels can lose contact only in one case - plane takes off - but to do so plane have to have speed > 0 -so logically plane never takes off. Your experiment is incorrect - treadmill should increase speed for ideal case - infinitely. But for real life this "infinity" limited by bearings
If you make it go faster than the threadmill, then of course it will take off at the moment the difference in speed equals the minimum takeoff speed (the stall speed). The idea is not for the plane to go faster than the threadmill but always at exactly the same relative speed and still takeoff, except that it then could not. The so-called Mythbusters also don't understand (or else ignored) this basic premise of the problem in their idiotic show.
This really explains the whole propeller vs. rolling friction thing very well. However I thought the claim was that the plane would be able to take off without making any forward motion relative to stationary objects, thanks to the treadmill. Apparently the treadmill proponents are only arguing about whether the plane can take off at all, period. So I guess it depends on what you thought the claim was.
god, you idiots who think the plain wont take off, please read this.
if the throttle is enough to push the plane say 20 mph on a normal surface then the treadmill does nothing, the treadmill will increase the speed of the wheels to 40 mph but the plain itself will move 20 mph. the plane goes 20 mph, the belt goes 20 mph, the wheels go 40 mph the plane goes 20 mph. if you still can't grasp that watch all of the many demonstrations
So basically, you're saying that when the plane is goign faster than the treadmill, it'll take off? WELL NEVER.... Planes don't take off unless air moves over the wings. That is the FUNDAMENTAL REASON for flight. Vacuum above, high pressure below. Lift. However, if the plane only MATCHES the speed of the treadmill, no flight, and a very angry you jumping up and down and wondering why your idea doesn't work. Books are fun to read, find one on flight.
@sim2lew Apparently, you need to read about flight. The treadmill has NO EFFECT on the airplane's ability to takeoff. If there was no rolling friction and the wheel bearings were completely frictionless and the airplane engine was OFF, you could not make the plane move no matter how fast you run the treadmill. The propeller is pushing against the AIR, not the ground, to make the airplane move forward. The airplane's ability to takeoff would only be affected if the air around the plane was moving
@jetengine7 You just don't get it. The propeller propels the plane forward, meaning the air over the wings moves because the plane is moving. Planes fly because of a difference in pressure on each side of the wing. The treadmill may as well not be rolling. If the plane is moving forward at the same speed that the treadmill moves backwards, then there is no air moving over the wing, no takeoff. God, some people are such retarded dumbfucks.
@sim2lew For the treadmill to stop the plane from taking off, it would have to provide a backward force equal to the forward force provided by the propeller. But the treadmill cannot because the wheels are freely spinning. If you put the plane on a treadmill and try to hold it in place with your hand, you will notice that it is very easy to stop it from going backwards. Even if you increase the treadmill speed, it will NOT get any harder to hold the plane in place. Think b4 you start insulting.
@jetengine7 Well, not true. Otherwise, every aeroplane on this earth would be moving, as the earth spins. There is friction between the wheel, ground and plane. The prop only overcomes the friction. If the plane isn't actually moving forwards, then it will not fly. If you hold the plane in your hand and make the prop spin fast, it will pull forwards, not up. Put the plane on the treadmill with prop not moving, turn on treadmill, plane shoots backwards. You are an idiot. Learn about aerofoils.
@frenchsaber Of course not. He has it on strings. However, the treadmill provides little to no impairment in it's ability to push itself with enough airspeed that, given more length, it could take off. Much how when they were testing driving a car onto a trailer, just because the wheels were spinning at 60 mph when they hit the gate, the car didn't launch itself up the gate, it continued moving up the trailer at about the same speed as it approached the trailer.
The problem in all this is the understanding of the question. If the treadmill induces a velocity on the plane that is equal and opposite to that of the velocity produced by the thrust of the aircraft, then obviously the plane will not take off.
Some people interpret it differently and this is where this debate comes in.
In theory, the plane can take off, but it would need about 150% the usual force to do so. that is assuming rolling without slipping, which is what a real plane would need.
The problem I had with the Mythbuster's episode was that in every case, the plane ended up moving forward (relative to the viewer). The idea is to get the plane airborne without having it move relatively forwards at all until the wheels left the ground. You've shown that the plane will move forwards as long as it can overcome the wheel spin friction. So in order to PROPERLY demonstrate this myth you have to apply braking force to keep the plane from moving forwards: it wont take off.
You obviously have no friends. wtf makes u think of this shit. y would u even put this stupid shit on youtube. im not surprised this was under suggestions when i searched fails.
If, like it says in the myth, the belt moves the same speed the plane does, constantly, the plane will always stand still, which means no airflow over the wings, thus the plane CAN NEVER TAKE OFF!!!
'@markobgva are you THAT stupid??? thinkn about it. the plane is going to take off regardless of the speed of the "treadmill" think about it. in order for the plane to sit still the wind over the wings would have to be in sync with the speed of the plane. so.....a plane on a treadmill just makes the wheels spin faster for it to take off..... its not a car you genius
You didn't understand, the speed of the conveyor belt didn't increase the friction, thus he kept increasing the conveyor belt and kept the plane stationary with the same amount of thrust (just enough to match the friction). Again, if the conveyor belt was going at 10x times faster, or 100x faster, he would still not need to use more thrust to keep it stationary, and the plane would still take off if he applied more thrust, the speed of the threadmill is irrelevant.
@markobgva The plane is propelled by a propeller, jet/turbine, etc. (Take your pick. It doesn't matter as the concept is the same in all cases) The wheels are not propelling the aircraft and thus will just spin to match the difference in speed between the ground/belt and the plane.
Since the engine (prop, jet, etc...) is pulling the plane through the air, the plane doesn't care what speed the ground is moving at, just the speed of the plane moving through the air.
@markobgva Wow, I can't believe how hard it is for people to understand! He's not trying to takeoff. The treadmill is too short for that. He is just showing you that the airplane will move forward no matter how fast the treadmill moves because the airplane is pushing against the AIR, not the ground. The wheels SPIN FREELY. The only way to prevent an airplane from taking off is with a huge tailwind. Moving the ground will never have any effect.
Plane will not take off. OMG, people are dumb as doors. If the thrust of the throttle on the plane is matching the speed of the tread mill the plane will be stationary. Meaning = 0 Air speed. 0 Air speed = 0 lift that = Not going to take off.
@neodocneodoc A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
@mikecamp6969 I cant see why people have a problem with this.. its good to see somone else understands it. the planes lift is developed from its speed RELATIVE TO SURROUNDING AIR, this is why real aircraft always land into wind, because if they fly with constant airspeed, but downwind they will have greater groundspeed, making it harder to land, if an aircraft were on a treadmill with a headwind equal to the take off speed, it would take off without moving, as it would from stationary ground.
@mikecamp6969 haha ive been laughing my ass off at how stupid all these videos are. the guy who made up the stupid question in the first place was either someone trying to purposely get at people who know how to use common sense, or just really really fucking dumb lol
@mikecamp6969 You've made the same mistake I did at first, which was to understand the problem as "if the treadmill provides the same backwards force as the propeller provides forward, will the plane take off?" In which case, your argument holds. But as the wheels are almost frictionless, the treadmill provides very little backwards force. If this were not true, a plane coming into land would massively stall the moment the wheels touched the tarmac. This clearly doesn't happen.
@mikecamp6969 You have got to be kidding me. What is so hard to understand about this? The airplane is pushing against the AIR which is stationary. No power goes to the wheels. They are FREELY SPINNING, except for the tiny bit of friction in the bearings. The treadmill can go 100mph and the airplane will STILL move forward when it's turned on, because the propeller is pushing against the AIR, which is STATIONARY. Now if there was a tailwind, that would make it harder for the plane to takeoff.
@mikecamp6969 Yes it would still take off. That is because the plane is not powered by a motor connected to a wheel but instead a propeller(s). this means that if there is thrust created by the propeller, the conveyor belt will have little or no effect on the plane as it would just make the wheels spin twice as fast. the aircraft will still be able to resume the take off but with the wheels traveling at twice the speed.
@wikigeek A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
@mikecamp6969 Air is the means by which airplanes achieve thrust. The treadmill does not move air. Therefore, taking rolling resistance into consideration, the treadmill has no effect on the planes ability to achieve thrust. Thus, the plane would still be able achieve the speed (air speed/lift) necessary to take off.
On a plane, the wheels are little more than free rolling casters, there is no power sent to them, they simply roll. All thrust comes from the engine/propellor.
you did a great job explaining this, much better than the entire mythbusters experiment. this should now clearly show to everyone how a treadmill doesn't matter, except for the initial rolling friction. I wish we could have frictionless wheel bearings to show that when the engine is off, the plane wouldn't move at all no matter what speed the treadmill was at.
@henman325 Exactly right. If you consider the wheel/ground interface as frictionless (which a smooth wheel is not that far off) then you can easily see that the ground, moving or not, provides no retardant force on the motion of the aircraft. The thrust from the prop can easily overcome this as if it's frictionless, there's nothing to overcome.
ok but i thought the question was would it take off? .. so say your at the the point where it was at around 3:15 ish and your were to try to make the plane take off WITHOUT increasing the speed of the plane would it take off? i dont think the scenario was can a plane go across a treadmill at whatever speed its if the plane and the treadmill were matched would the plan be able to take off.
but maybe i miss understood the hypothetical situation
Yeah, once you over come the friction, nothing happens. If anything, as the conveyor increases speed, you could get some airflow over the stationary plane due to "no slip condition," but that's it :P Thanks for showing this to those who thought it couldn't take off.
@baboonFreak11 seems to be onto something. When a person runs on a treadmill, you don't feel a breeze, you're for all purposes, stationary. Get off that tread mill and run normally, get a breeze. If a giant tread mill was rolling at 200 mph and a plane was throttled up to 200 mph as well, there would be no wing lift....right? Say it's throttled to 500 mph and the treadmill is at the same...still wouldn't have wing lift, right?
@FlamingoTropicalSno The propulsion method. When you run on a tread mill, you are using your legs to propel yourself forward by pushing on the treadmill belt, but the belt is going the opposite direction at the same speed.
The airplane/jet propels itself against the AIR, which is totally independent of the treadmill belt. The wheels are free spinning, not pushing against the belt.
@neodocneodoc But if if the plane is stationary due to the treadmill neutralizing the plane's forward velocity, wouldn't the plane not be pushing against the air? With this in mind, the air pressure below and above the wings would stay the same, resulting in no lift...
The plane propels itself "against the AIR" when it's actually flying, but when it's taking off it rolls on the ground in order to get air to flow over its wings until that flow is fast enough for the airplane to takeoff. If the plane remains stationary, no air at all will flow over its wings (on a day with calm wind), so how would it take off?
@Jakareh75 Unbelievable. So your saying the airplane propels itself against the AIR when it is flying, which is true. What makes you think that it is different when it is on the ground? The engines are still pushing against the AIR to get it moving on the ground. If it was pushing off the ground, then the wheels would have to be powered, but the ARE NOT. The wheels are freely spinning! Movement of the ground is irrelevant.
By the way, you're also wrong about a threadmill moving in the same direction as the airplane. That would actually help it to takeoff because it would increase airspeed. The exact same principle applies to the catapults used in aircraft carriers.
@Jakareh75 The treadmill will NOT help or stop the plane from taking off no matter what direction or speed it goes. The airplane is pushing against the AIR to move, NOT the ground. The wheels are freely spinning and only have a tiny amount of friction in their bearings. The only way to help a plane takeoff is with a headwind. To stop it from taking off, you need an enormous tailwind.
@jetengine7 Fuck, you're stupid. Planes fly because of air moving over the wings. The propeller isn't there to do that, the propeller makes the plane move forward, and the air around the plane moves over the wings. Notice how there is no movement of air on the treadmill? It's not a fucking space shuttle.
@sim2lew I never cease to be amazed by peoples' ignorance and stupidity. I never said the propeller provides the airflow over the wings. Even an idiot knows that it doesn't. The propeller provides forward thrust by pushing air backwards, because Newton's third law says for every action there is an equal and opposite reaction. So the air being forced backwards by the propeller exerts a force on the propeller blades, pulling the whole plane forward. Notice that the ground is never involved.
@jetengine7 That doesn't make the plane take off. The plane just sits there going nowhere. if the ground wasn't involved, planes all over the world would be moving at thousands of miles per hour without the engines on. That includes RC planes. Friction occurs everywhere.
@sim2lew There is only a tiny amount of friction in the wheel bearings and this friction does not change no matter how fast or how slow the wheels spin. The prop will always have to overcome the same tiny amount of friction no matter how fast the wheels are spinning.
@sim2lew Really? The friction in the wheel bearings gets greater with speed? What world do you live in? Bearings have a coefficient of kinetic friction, which is constant. No matter how fast a wheel spins, the friction in the bearing STAYS THE SAME! Only certain types of friction increase with speed, such as air friction. I have a 3.96 GPA. I work with wheels, bearings, airplanes, and turbine engines daily. I know what I'm talking about. You obviously haven't understood anything I've said.
@sim2lew The reason that airplane wheels don't spin as the Earth moves underneath them is because the Earth is moving at an extremely slow and constant speed, not accelerating. This movement of the Earth is nowhere near enough to overcome the friction in the bearings. If is was significant at all, then you would feel like your feet were being pulled out from under you when you stood up, like standing in a bus while it's accelerating, braking, or turning.
@jetengine7 HAHAHA slow my arse. 700-900mph? Wait, so you're saying if you turn on the treadmill, hold the plane for a while and then let go when the wheels are turning at the treadmill speed, the little plane won't move? xD you're funny. A plane can only take off when the air pressure under the wings is greater than the pressure above. The treadmill means that the wings are stationary and the air pressures are equal. That is why the plane doesn't fly, dumbfuck. It's simple.
@sim2lew I didn't say the plane won't move when you let go of it. Of course it's going to move backwards because of the friction in the wheel bearings. I said if you increase the speed of the treadmill WHILE you're HOLDING the plane, it WON'T get any harder to hold it in place. The plane WON'T move backwards with any more force than it did when the treadmill was slower. Learn to read. The treadmill DOES NOT keep the plane in place b/c the wheels compensate for the treadmill by spinning freely!
@sim2lew It doesn't matter how fast the Earth spins. As long as it spins at a CONSTANT speed, it will overcome the inertia of an airplane and make it move with it. That's why you don't see the wheels rolling underneath parked planes with the brakes released. That's also why your car wheels don't start spinning as the Earth moves underneath them when you put your car in neutral on a level surface. On the treadmill, however, the wheels do spin underneath the plane even when the plane is stationary
@jetengine7 No, the reason planes don't move around is because the earth and air are all moving at a constant speed, and gravity keeps the planes on the ground. There is a considerable force between them. You seem to underestimate forces.
@sim2lew If the treadmill was exerting any considerable backwards force on the airplane then you wouldn't be able to hold it in place as the treadmill got faster. The treadmill will only exert its full force if the airplane's brakes are applied.
@sim2lew I'll say it again. Airplanes push against the air to move, not against the ground. Just like you push against water to swim, airplanes push against a fluid too: air. Imagine walking on a treadmill at the bottom of a pool. If you're always touching the treadmill does it make it any harder for you to swim forward. As long as your feet keep up with the treadmill like the airplane's wheels do, all you have to do is push back against the water with your hands and you will move forward.
in your example the treadmill is going 200mph one way, and the planes thrust is pulling the plane 200mph the other way. The planes wheels are free spinning which means they would be going 400mph, but this means nothing in the plane taking off.
@FlamingoTropicalSno you're missing the fact that you can't throttle a plane up to 200 mph. The throttle affects thrust which is a force and not a speed/velocity. Basically a real plane needs very little of its full thrust to overcome the friction of the wheels. And conveyor belt speed does not really increase that friction. At so low thrust levels the airplane would not get airborne even on solid ground.
So what's ground speed have to do with airplanes. I thought a plane used airspeed. On an aircraft carrier, they still point her into the wind for launching and recovery.
Well i guess when you take a jumbo jet that ways tons, its going to put more friction on the bearings other than styrophome and plastic. But idk you took physics so. i guess you would know more.
@GamerLP14 you are correct...there would be more friction on the wheel bearings...absolutely. Keep in mind, though, they can also produce more thrust...like 250,000 lbs. of thrust, which would easily overcome the friction.
Remember that a jet lands between 130-160 knots (for a 747) and the 'treadmill' is effectively zero...are there any ill effects to the plane??? No. Conceptually that is the the same as the jet standing still and the treamill going 160 knots in the other direction.
I understand this. I understand that if a plane was on a treadmill it would be able to overcome the speed and take off, what bothers me is If you were to match the speed perfectly so the plane is stationary as the treadmill rolls and you had a plane with flaps....it wouldn't take off standing stationary. There wouldn't be any airflow to create the lift through the wings. Thats what drove me crazy about the mythbusters episode.
I dont even think i get the conundrum. What does the power of the wheels have anything to do with wind hitting the planes wings? The air aorund the tradmill will be moving at 0mph (in a vaccum :P ) and obviously not produce lift even if the treadmill was going 3240987 mph. I dont get it.
@novahcac The question is stated as though the treadmill would hold the plane in the same position relative to the air. The treadmill will be unable to keep the plane stationary relative to the air (since it is propelled with air movement, not force to the wheels), so the plane will continue to move forward relative to the air, achieve lift, and take off.
@neodocneodoc In the case of a real plane whose wheels have nothing to do with its propulsion, and neither does the speed of the wheels' movement, Why isnt it obvious to everyone ever that the only thing that matters is the speed of the plane relative to the wind around it? Who cares about a treadmill, all it will do is move the wheels. If they are 'perfectly greased' theoretically the plane should stay in one spot, and with any propulsion it would move forward. I still don't see the conundrum.
Real planes only use their wheels to roll, they don't drive the plane. The plane's engines are what drive it, RC planes don't just use their wheels to roll.
No. What is happening is, you've become so attached to your own creation that you can't entertain there are ground speed viewpoints and airspeed viewpoints. You will insist on no ambiquities. You've walked into a well worded conundrum. Admit it. It's the first step to recovery :) Three times you've put words in my mouth and and negated your own thinking. You've even demanded I Stop thinking any way but yours, lol. That's uninteresting. Good luck with your world. Thanks for playing.
@MsSimplegreen this isn't a special relativity question. I posted the question I was basing my experiment on...I did not put words in your mouth once. I did not negate my own thinking. I never demanded that you stop thinking any way you want. I just asked for a free body diagram and math...that is all. But since you feel it is a conundrum, you refuse. To each their own.
Third, you may try to 'squeek' around the logic by posing that the plane possibly has a prop wash strong enough to cause vertical lift flowing by the wings (prop forward). A "Plane", however, would mean "most" planes and most planes can't hang by the prop and go vertical. So that would be a semantic attempt at a solution, not a solution. But hey, why not? We've already got an imaginary infinite treadmill. "Plane v Treadmill Solved!"? Chuckle.
Sconz32 has it, "You don't understand the premise."
Second, "the treadmill can do nothing to keep the plane from moving forward". Um, No Sir. Thinking you "get it" when you visualize the wheels aren't the supplied power but the prop is, doesn't negate the premise of a magical treadmill that can always be faster than the plane can go forward. Matched speed, no forward motion, no lift. One could also mix the real with the imaginary in the reverse by, "Try running on a 30 mph treadmill". At some point, a real world wheel bearing will burn up.
All you "prove" is that with a LIMITED speed treadmill, you can overcome it with the throttle. The original wording says the treadmill can ALWAYS match the plane. FINITE plane, INFINITE treadmill. Get it? You're imagining this treadmill running even super fast and the plane's wheels matching it, but the friction being small, lets the plane surge forward and zoom off into the sunset, lol. However, the planes prop power has a limit, the treadmill doesn't. This is the myth 70NYD tried to point out.
Sorry, but it's a FAIL. First, it's a stupid argument. Set up and no doubt still laughing by the originator. An unlimited and Theoretical infinite speed treadmill is mixed with real world mechanics of a prop plane on wheels. You fell for this first conundrum (unanswerable), not the people trying to point out the several falacies to you.
The fact that the rolling friction of the wheels, is miniscule compared to the power of the prop to move the plane forward can't be used. It's Finite.
@MsSimplegreen Show me your bearing data...I showed mine (somewhere in here)...do you know how low friction wheel bearings are? Next time you are in a car, see how far you will roll in neutral. Miles.
The plane will move forward, and my argument CAN be used. Doesn't matter if the treadmill has 'infinite speed'...the treadmill matches the planes forward speed, but in the opposite direction...not blast to infinity to try to keep it from moving.
@neodocneodoc Bearing data? Unnecessary tangent. Clearly I used your givens. Friction low, thrust main factor. The premise mixes impossible (unlimited treadmill) with real world (plane). So viewpoint determines solution. If you still pursue it, the Crux is, that the treadmill can always be advanced to nuetralize planes forward motion because planes power is Finite, the treadmill has no limits. You Matched planes speed to treadmill before, plane going forward is a mismatch. Treadmill is slower.
@neodocneodoc Real plane on real runway; 2 foot round wheel Must move forward 2 feet, again and again, creating apparent wind for lift. Whether the thrust is a prop, jet engine or atlas booster it has a Finite limit. Everytime plane rolls wheel forward 2 feet, the no limit treadmill can counteract that 2 feet. That is Matching the speed of plane with treadmill. Infinite treadmill can match any plane's speed, up to burning up the wheels. Would also negate liftoff btw. Keep thinking, you're close.
@MsSimplegreen The question was not whether the treadmill can move fast enough to keep the plane stationary. The question talks about MATCHING speed. The plane goes forward at 5 knots, the treadmill goes in the opposite direction at 5 knots....not 500 knots to keep it stationary. Don't modify the question to make it fit your answer.
@neodocneodoc If the treadmill indeed matches the planes speed, it will be stationary. Stop misinterpreting the premise to fit yours :) The speed is relative to the observer, not the plane.
@neodocneodoc It's a Conundrum.No answer. The originator mixed the Real, the Unreal, and semantics and likely didn't take a side. It's for fun. All the mech, physics, geometry formulas won't solve it. Why? Real world formulas don't mix with semantics. If you decide to go down the rabbit hole, fine. Just know switching to the impossible (unlimited treadmill) or to real world data can disprove a chosen position. *Match* is parsed. Sconz32, "You don't understand the premise of the argument"
@neodocneodoc Because Liftoff *is* the goal, it *does* imply if the plane can be kept stationary. That's the whole point. Saying "wheels don't matter or once a given plane speed happens the belt must maintain it and added power makes it lift off" is a misinterpretation. Wheels matter. Put 747 on revolving runway, held by a cable. Runway to 400mph, uncable. See, plane doesn't move! Oh wait, minutes later it creeps backwards increasingly. Reverse also true. Runway, via wheels can nuetralize it.
@MsSimplegreen As i say in the video (I believe..it has been years) the ONLY force that the treadmill will provide is the rolling friction that it creates by the added rotational speed of the wheels...that is it.
Show me your free body diagram and your math (feel free to plug in the bearing data values...you will need them) and show me how a treadmill going the opposite direction AT THE SAME SPEED will keep it from moving forward
The question wasn't CAN a treadmill keep it from taking off.
Can there be sufficient airflow going over and under the wings to produce lift if it is not actually moving through space? I don't know. It depends on whether the conveyor moves the air along towards the plane.
It's like this: You are standing on a skateboard on a long treadmill. It has long handrail next to it. You start pulling yourself forward with the handrail (like plane "pulls" itself forward with air). The treadmill starts moving at same speed at the opposite direction but it doesn't have any affect in your forward movement because you are UNCOUPLED from the treadmill by the wheels of the skateboard (just as a plane is by its wheels).
onpahanvaan 1 month ago
You walk on treadmill and your "speed" is matched by the treadmill you will of course stay stationary relative to the surroundings. If planes speed is matched by treadmill it means the plane is actually moving forward (relative to surroundings) at certain speed and the treadmill with same speed at opposite direction. (Meaning planes speed relative to treadmill surface is double its speed relative to surroundings.) Plane can only regulate its speed relative to air and is UNCOUPLED from treadmill
onpahanvaan 1 month ago
1.
I see why people have a problem with this. It's sort of a trick question because the real core question of it is: WILL THE PLANE MOVE FORWARD OR NOT? Most people intuition says NO because we are used to transportation like walking and cars which "push" from ground to move forward. Then people think the problem of the question is will the plane fly if it's stationary relative to air and then the answer would of course be NO. But it WILL move forward because it pushes the AIR to move.
onpahanvaan 1 month ago
Yes you are
shyheim101 2 months ago
Umm taking off a running treadmill is impossible due to the lack of currents that the wings create lift on... Am i right nerds?
egroegcimorg 2 months ago
skip the chat to 2:00
motals 3 months ago
sounds like its wheels are going to explode
tonyspazfur 5 months ago
Well done, you've proved that bad wheel bearings have high friction. Do this with a real plane with real wheels and you'd have to move the belt at hundreds of miles an hour to stop it. In fact the tires would probably burst from overheating before drag from the wheel bearings became significant.
AJSTho 5 months ago
I think the problem is with this debate is that when people say "a plan can take off using a treadmill" there thinking in the sense that if a plain needs to get to say 120mph, and you take a treadmill to 120 mph, that it will be able to take off, and of course this is not the case because there is no lift, however since the engine powers the jets or whatever type of plane your using is, and not the wheels, it won't affect the plains ability to take off. But it still needs lift.
Asodinn 6 months ago
ok this is like walking on the moving sidewalks at airports if you walk at the EXACT same speed against the treadmill then you will be moving nowhere RELATIVE to the non moving part such as the floor, same with a plane if its not moving faster than the floor there is no air going over the wings and therefore NO LIFT WHICH MEANS NO TAKEOFF
TheIceychill2 8 months ago
@TheIceychill2 The treadmill does not stop the plane, the force of friction is nothing compared to the thrust of the plane.
11cookeaw1 7 months ago
@11cookeaw1 well of course you CAN takeoff from a treadmill whatever speed its going backwards is the extra you need to compensate for, BUT IF THE SPEEDS ARE EXACTLY THE SAME NO AIR GOES OVER THE WING = NO LIFT = NO TAKEOFF
TheIceychill2 7 months ago
@TheIceychill2 They both go at the plane's take off speed, there is simply no way the treadmill can hold the plane back at that speed, the plane will move and take off. The treadmill's friction will have similar effects on the air as the plane... Anyway, the plane's engines will push air backwards at high speeds.
11cookeaw1 6 months ago
@TheIceychill2 blog.xkcd.com/2008/09/09/the-goddamn-airplane-on-the-goddamn-treadmill The plane WILL move forward. It WILL tale off.
11cookeaw1 4 months ago
"A plane is on a runway that is a giant conveyor belt. As the plane moves, the conveyor will exactly match that speed but in the reverse direction."
That definition of the problem has any physical sense only to an absolutely uneducated moron.
PKSnsk 9 months ago
The earth is a giant runway. Hopefully you can take off or else we would be in deep trouble. If we could in fact take planes off a treadmill then we would never need long runways again. The problem was if a plane can take off when the wheels match the speed of the conveyor belt. Video here shows plane probably with a front propeller (cant see it) that provides just enough air movement for the wings to generate lift. Modern aircraft push rather than pull to generate lift.
detectiveinspekta 10 months ago
This is the Physics For Dummies version of this thought problem. It is not the original version of it. In the original version the speed of the treadmill matches the speed of the wheels. In the version shown here the speed of the wheels is greater. The original is tougher but there is a force that will hold it in place. The original version means that the belt will accelerate. The changing rotational inertia of the wheels creates a back force. If belt accelerates fast enough it will work..
subductionzone 11 months ago
@subductionzone Rotational inertia stopping a plane's mass that is orders of magnitude greater than the wheels mass. Your logic is flawed. In this version here the speed of the wheels matches the speed of the treadmill...see, plane not moving anywhere....then I accelerate the treadmill and it has no effect.
Do the mathematics behind it....you will see. Acceleration is not magic. Talk about acceleration...look at a plane landing. In your concept the plane would come to an instant stop.
neodocneodoc 10 months ago
@neodocneodoc I, and others have done the math. A personage no less than Cecil Adams of The Straight Dope has admitted that this can theoretically be done if the acceleration is great enough in a revisit to this problem. It does take a very high rate of acceleration, for a typical jet air liner we have calculated examples and found it would require 50 to 100 g's to keep say a 737 in place. By the way, if you Google search enough you will find that the "matches wheel speed" is the oldest versi
subductionzone 10 months ago
@subductionzone did you take into account the friction between the tire and the runway? So you're trying to tell me that an instantaneous force of 100G's will still allow the tires to grip? If tires were that good nothing would ever skid. Think about it. The rotational inertia of the wheel would resist this large acceleration and the tire would just skid...i.e. like skis on snow.
neodocneodoc 10 months ago
@neodocneodoc Yes we did. There are a few planes that could produce a high enough thrust to cause the plane's tires to skid, high power fighter jets or acrobatic planes. But the vast majority would not break lose. And yes, if the plane breaks free it is able to take off. Obviously there are no 50 to 100 g treadmills out there, or wheel bearings, tires, or a belt that could stand up to the sort of speeds and heat that would arise from this. But it can be done, as a thought problem.
subductionzone 10 months ago
@subductionzone my point was not that whether the plane's force could make the tires slip...it was that if you applied a substantial acceleration to the treadmill, the rotational inertia would 'want to' hold the wheel still. That 100G's that you are talking about would have to be transmitted to the wheel without slippage; if you have slippage, your point is moot. If it was a geartrain, another question, but you are talking about rubber on asphalt.
neodocneodoc 10 months ago
@neodocneodoc Remember you are only accelerating the wheels, not the whole plane. When a plane lands its wheels, very temporarily, accelerate at an even higher rate. That creates a noticeable jerk, that is before the brakes are applied. The force that the wheels can withstand can be calculated by using the static friction of the wheels on asphalt with the weight of the plane over them, traction and static friction are very closely related.
subductionzone 10 months ago
@subductionzone 99% of cases have the wording saying the belt matches the plane's speed not the wheels. I can't even find an exception. But more importantly, the thought experiment very obviously is testing whether a treadmill can stick a plane in place in the SAME WAY it sticks a person or car, otherwise it would HAVE to ask "how could a treadmill keep an accelerating plane stationary relative to the air" Why? Tracking wheels would be STUPID because the plane could be on skis! No tracking!
nerfmyaccount 6 months ago
@nerfmyaccount It is higher now that the Mythbusters, who have a huge web following did their show, but the original version had the speed of the wheels matching the speed of the treadmill. Or perhaps I should say the oldest known version. And your claim that tracking the speed of the wheels is "STUPID" is just because you don't like that version of this problem.
The version you tested is high school physics at best. The original version takes more knowledge. And is more interestin
subductionzone 6 months ago
@nerfmyaccount Reply number 2. And your skis statement is incredibly inane. It is in the wording of the original version that the plane has wheels.
But you seem to understand one thing. If the plane was on skis, ideally it would not matter if the belt was accelerating or not. It would still take off.
subductionzone 6 months ago
@subductionzone that's a dumb and unlikely interpretation of the original problem sorry. let's track the wheels for no reason when we could just as easily track the wings and accelerate the treadmill to whatever necessary keep them relative to the air regardless of what connects the plane to the belt (wheels or skis) maybe the math is high school physics but the logic of the question is clearly above you. better luck next time.
nerfmyaccount 6 months ago
@nerfmyaccount How is the interpretation that speed is to be measured at the wheels a "dumb interpretation"? I have gone over this with a person who is fluent in Russian, born there, and was an undergrad in physics. The wording of the original version is what it is. Again, your version is extremely easy to understand. A ninth grader should be able to get it. The original version is a bit trickier, and that is what makes it a better brain teaser. It takes a bit more physics to get it.
subductionzone 6 months ago
@nerfmyaccount You seem to be overly fond of your rather simplistic test. A analysis of forces on the plane would clearly show that it could fly with your preferred version. Again, ninth grade physics at best. In fact your version asks basically if a plane moves forward at its take off speed can it take off? Talk about a dumb and pointless question. Now the version I like is a bit pointless too, by definition the plane sits in place. It also asks if there is a force on the plane. There is
subductionzone 6 months ago
@subductionzone The point of the question is not complex physics but being able to override intuition to engage critical thought and realize that our personal experiences shape our macro interpretations of the world. We've walked on treadmills. We exercise on them. We use them at airports. We go up escalators. We've seen cars tested on them to stress the engine. The natural conclusion is to assume planes will stick on them, the test is to jump start your brain to break the intuition.
nerfmyaccount 6 months ago
@subductionzone yes for some it is a simple and trivial problem. But for most people the complexity is NOT the physics but the intuition. If you think the average person views the world through a proper objective lens then I want to trade worlds with you. The question (as popularized all over the internet) DOES ask "can a plane take off with it's takeoff airspeed" but the hard part is getting people to realize that's what it's asking! If you think it's easy, find someone on the street and ask
nerfmyaccount 6 months ago
@nerfmyaccount You very well may be right about the average person's perception. But this originally arose at a place where hopefully the students were intelligent enough to get the answer. Yes, I have seen many people get even your version of the problem wrong. An in reply to your previous post the physics is not all that complex. A first year physics major should be able to understand the forces involved.
I guess the version you use could depend on your audience.
subductionzone 6 months ago
A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
mikecamp6969 11 months ago
@mikecamp6969 If friction has little effect, the length of the runway would not need to be longer...you almost have it.
neodocneodoc 11 months ago
@neodocneodoc Hey clownballs, try reading what I said. I never stated the runway had to be any longer. I said the runway would need to be the proper length to gain airspeed to take off. So, using my example of a 747 if it was trying to take off from a treadmill.. the treadmill would need to be 6500 to 7500ft in length. Get it clueless? Using another example; If your lame ass model plane needed 10ft on the ground to take off, it would need a 10ft treadmill to take off. Pay attention class.
mikecamp6969 10 months ago
@mikecamp6969 No need to be an ass.
neodocneodoc 10 months ago
This is just a moving surface. Once overcoming surface friction, thrust does whatever it wants, it doesn't create a special airflow allowable for lift!
Dominoes282 1 year ago
I'll repost my last comment: A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
mikecamp6969 1 year ago
And at 10mph it moved forward at about 15-20 mph relative to the treadmill speed. A speed I doubt that plane would be able to match on its own. Treadmill has no effect. Great video!
It would be cool if you cold somehow do a video demonstrating air speed over ground speed. Showing a plane take off at a very low gs or even flying backwards, it would be awesome (if you could find an environments that you could easily film).
destin325 1 year ago
2 mins of bs get on with it
Ditchpigs1 1 year ago
why the fuck is everyone wasting time bitching about science? he mad the vid thank him then fuck off... someone makes a video to entertain you and you hop on their nuts telling them everything you disagree with? get a life faggots anyways i found this vid from watching fat chicks fall off tread mills so you can understand my little interest in the video itself but anyway this would be why i dont read youtube comments their always fucking retarded
WildSecks 1 year ago
@roofy2k I'm an engineer...I did the free body diagram. It will move forward and take off.
neodocneodoc 1 year ago
video proves a plane can't take off from a treadmill.
treadmills are only about 3 feet long and not long enough for it to take off.
taledarkside 1 year ago
omg so geeky just get to the bloody point jesus
lolageHannah 1 year ago
no strings attached....... im not so sure
TheEmanBaird 1 year ago
guys, you just misunderstood the question
treadmill should have adaptive speed - which means plane speed should be 0 (zero) while wheels contact belt. Wheels can lose contact only in one case - plane takes off - but to do so plane have to have speed > 0 -so logically plane never takes off. Your experiment is incorrect - treadmill should increase speed for ideal case - infinitely. But for real life this "infinity" limited by bearings
m10306 1 year ago
If you make it go faster than the threadmill, then of course it will take off at the moment the difference in speed equals the minimum takeoff speed (the stall speed). The idea is not for the plane to go faster than the threadmill but always at exactly the same relative speed and still takeoff, except that it then could not. The so-called Mythbusters also don't understand (or else ignored) this basic premise of the problem in their idiotic show.
Jakareh75 1 year ago
This really explains the whole propeller vs. rolling friction thing very well. However I thought the claim was that the plane would be able to take off without making any forward motion relative to stationary objects, thanks to the treadmill. Apparently the treadmill proponents are only arguing about whether the plane can take off at all, period. So I guess it depends on what you thought the claim was.
narutodayo 1 year ago
shutup and do it!
FPVsean 1 year ago
god, you idiots who think the plain wont take off, please read this.
if the throttle is enough to push the plane say 20 mph on a normal surface then the treadmill does nothing, the treadmill will increase the speed of the wheels to 40 mph but the plain itself will move 20 mph. the plane goes 20 mph, the belt goes 20 mph, the wheels go 40 mph the plane goes 20 mph. if you still can't grasp that watch all of the many demonstrations
mortacrify 1 year ago
So basically, you're saying that when the plane is goign faster than the treadmill, it'll take off? WELL NEVER.... Planes don't take off unless air moves over the wings. That is the FUNDAMENTAL REASON for flight. Vacuum above, high pressure below. Lift. However, if the plane only MATCHES the speed of the treadmill, no flight, and a very angry you jumping up and down and wondering why your idea doesn't work. Books are fun to read, find one on flight.
sim2lew 1 year ago
@sim2lew Apparently, you need to read about flight. The treadmill has NO EFFECT on the airplane's ability to takeoff. If there was no rolling friction and the wheel bearings were completely frictionless and the airplane engine was OFF, you could not make the plane move no matter how fast you run the treadmill. The propeller is pushing against the AIR, not the ground, to make the airplane move forward. The airplane's ability to takeoff would only be affected if the air around the plane was moving
jetengine7 1 year ago
@jetengine7 You just don't get it. The propeller propels the plane forward, meaning the air over the wings moves because the plane is moving. Planes fly because of a difference in pressure on each side of the wing. The treadmill may as well not be rolling. If the plane is moving forward at the same speed that the treadmill moves backwards, then there is no air moving over the wing, no takeoff. God, some people are such retarded dumbfucks.
sim2lew 1 year ago
@sim2lew For the treadmill to stop the plane from taking off, it would have to provide a backward force equal to the forward force provided by the propeller. But the treadmill cannot because the wheels are freely spinning. If you put the plane on a treadmill and try to hold it in place with your hand, you will notice that it is very easy to stop it from going backwards. Even if you increase the treadmill speed, it will NOT get any harder to hold the plane in place. Think b4 you start insulting.
jetengine7 1 year ago
@jetengine7 Well, not true. Otherwise, every aeroplane on this earth would be moving, as the earth spins. There is friction between the wheel, ground and plane. The prop only overcomes the friction. If the plane isn't actually moving forwards, then it will not fly. If you hold the plane in your hand and make the prop spin fast, it will pull forwards, not up. Put the plane on the treadmill with prop not moving, turn on treadmill, plane shoots backwards. You are an idiot. Learn about aerofoils.
sim2lew 1 year ago
mythbusters tested it! it works!
MrBrentMichael 1 year ago
It didn't take off. It won't take off.
frenchsaber 1 year ago
@frenchsaber Of course not. He has it on strings. However, the treadmill provides little to no impairment in it's ability to push itself with enough airspeed that, given more length, it could take off. Much how when they were testing driving a car onto a trailer, just because the wheels were spinning at 60 mph when they hit the gate, the car didn't launch itself up the gate, it continued moving up the trailer at about the same speed as it approached the trailer.
AreThereNoMoreNames 1 year ago
The problem in all this is the understanding of the question. If the treadmill induces a velocity on the plane that is equal and opposite to that of the velocity produced by the thrust of the aircraft, then obviously the plane will not take off.
Some people interpret it differently and this is where this debate comes in.
In theory, the plane can take off, but it would need about 150% the usual force to do so. that is assuming rolling without slipping, which is what a real plane would need.
AncientSGA 1 year ago
Nice work.
The problem I had with the Mythbuster's episode was that in every case, the plane ended up moving forward (relative to the viewer). The idea is to get the plane airborne without having it move relatively forwards at all until the wheels left the ground. You've shown that the plane will move forwards as long as it can overcome the wheel spin friction. So in order to PROPERLY demonstrate this myth you have to apply braking force to keep the plane from moving forwards: it wont take off.
c3nty2 1 year ago
The propeller is pushing wind across the airfoil(the wings) to provide lift.
This experiment could not be reproduced with a plane that has its propeller behind the airfoil.
rmillavec 1 year ago
@rmillavec wrong...that is not how an airplane works
neodocneodoc 1 year ago
@neodocneodoc In this case i believe it is....
rmillavec 1 year ago
You obviously have no friends. wtf makes u think of this shit. y would u even put this stupid shit on youtube. im not surprised this was under suggestions when i searched fails.
zPNINJ4 1 year ago
@zPNINJ4 will you be my friend? I'm soooooo lonely.
neodocneodoc 1 year ago
If, like it says in the myth, the belt moves the same speed the plane does, constantly, the plane will always stand still, which means no airflow over the wings, thus the plane CAN NEVER TAKE OFF!!!
markobgva 1 year ago
@markobgva You are wrong...you didn't even watch the video.
neodocneodoc 1 year ago 4
'@markobgva are you THAT stupid??? thinkn about it. the plane is going to take off regardless of the speed of the "treadmill" think about it. in order for the plane to sit still the wind over the wings would have to be in sync with the speed of the plane. so.....a plane on a treadmill just makes the wheels spin faster for it to take off..... its not a car you genius
dubspins 1 year ago
@markobgva
You didn't understand, the speed of the conveyor belt didn't increase the friction, thus he kept increasing the conveyor belt and kept the plane stationary with the same amount of thrust (just enough to match the friction). Again, if the conveyor belt was going at 10x times faster, or 100x faster, he would still not need to use more thrust to keep it stationary, and the plane would still take off if he applied more thrust, the speed of the threadmill is irrelevant.
ArmandoXIII 1 year ago
@markobgva The plane is propelled by a propeller, jet/turbine, etc. (Take your pick. It doesn't matter as the concept is the same in all cases) The wheels are not propelling the aircraft and thus will just spin to match the difference in speed between the ground/belt and the plane.
Since the engine (prop, jet, etc...) is pulling the plane through the air, the plane doesn't care what speed the ground is moving at, just the speed of the plane moving through the air.
Palanthas1986 1 year ago
Well, as I saw, the plane did not take off, did it?
markobgva 1 year ago
@markobgva did you listen to the reason?
neodocneodoc 1 year ago
@markobgva Wow, I can't believe how hard it is for people to understand! He's not trying to takeoff. The treadmill is too short for that. He is just showing you that the airplane will move forward no matter how fast the treadmill moves because the airplane is pushing against the AIR, not the ground. The wheels SPIN FREELY. The only way to prevent an airplane from taking off is with a huge tailwind. Moving the ground will never have any effect.
jetengine7 1 year ago
Plane will not take off. OMG, people are dumb as doors. If the thrust of the throttle on the plane is matching the speed of the tread mill the plane will be stationary. Meaning = 0 Air speed. 0 Air speed = 0 lift that = Not going to take off.
Dumb topic.
mikecamp6969 1 year ago
@mikecamp6969 I totally agree with you....
markobgva 1 year ago
@mikecamp6969 Yes, you are.
neodocneodoc 1 year ago
@neodocneodoc A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
mikecamp6969 1 year ago 2
@mikecamp6969 I cant see why people have a problem with this.. its good to see somone else understands it. the planes lift is developed from its speed RELATIVE TO SURROUNDING AIR, this is why real aircraft always land into wind, because if they fly with constant airspeed, but downwind they will have greater groundspeed, making it harder to land, if an aircraft were on a treadmill with a headwind equal to the take off speed, it would take off without moving, as it would from stationary ground.
rickrollification 4 months ago
@mikecamp6969 haha ive been laughing my ass off at how stupid all these videos are. the guy who made up the stupid question in the first place was either someone trying to purposely get at people who know how to use common sense, or just really really fucking dumb lol
ryno2085 1 year ago
@mikecamp6969 You've made the same mistake I did at first, which was to understand the problem as "if the treadmill provides the same backwards force as the propeller provides forward, will the plane take off?" In which case, your argument holds. But as the wheels are almost frictionless, the treadmill provides very little backwards force. If this were not true, a plane coming into land would massively stall the moment the wheels touched the tarmac. This clearly doesn't happen.
potkettle 1 year ago
@mikecamp6969 You have got to be kidding me. What is so hard to understand about this? The airplane is pushing against the AIR which is stationary. No power goes to the wheels. They are FREELY SPINNING, except for the tiny bit of friction in the bearings. The treadmill can go 100mph and the airplane will STILL move forward when it's turned on, because the propeller is pushing against the AIR, which is STATIONARY. Now if there was a tailwind, that would make it harder for the plane to takeoff.
jetengine7 1 year ago
@mikecamp6969 Yes it would still take off. That is because the plane is not powered by a motor connected to a wheel but instead a propeller(s). this means that if there is thrust created by the propeller, the conveyor belt will have little or no effect on the plane as it would just make the wheels spin twice as fast. the aircraft will still be able to resume the take off but with the wheels traveling at twice the speed.
wikigeek 1 year ago
@wikigeek A plane cannot take off with ZERO airspeed. I agree, that your test shows that rolling friction doesn't mean anything but if you wanted to have a 747 take off it still would need the required length of runway to take off. Yes, the thrust will over come the treadmill speeds but it still needs the distance to take off. So technically, yes(747) it can take off from a treadmill but it would need a treadmill that was 6500 to 7500ft in length to do it. Treadmill = dumb.
mikecamp6969 11 months ago
@mikecamp6969 Air is the means by which airplanes achieve thrust. The treadmill does not move air. Therefore, taking rolling resistance into consideration, the treadmill has no effect on the planes ability to achieve thrust. Thus, the plane would still be able achieve the speed (air speed/lift) necessary to take off.
On a plane, the wheels are little more than free rolling casters, there is no power sent to them, they simply roll. All thrust comes from the engine/propellor.
shredicon86 1 year ago
you did a great job explaining this, much better than the entire mythbusters experiment. this should now clearly show to everyone how a treadmill doesn't matter, except for the initial rolling friction. I wish we could have frictionless wheel bearings to show that when the engine is off, the plane wouldn't move at all no matter what speed the treadmill was at.
henman325 1 year ago
@henman325 Exactly right. If you consider the wheel/ground interface as frictionless (which a smooth wheel is not that far off) then you can easily see that the ground, moving or not, provides no retardant force on the motion of the aircraft. The thrust from the prop can easily overcome this as if it's frictionless, there's nothing to overcome.
potkettle 1 year ago
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henman325 1 year ago
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henman325 1 year ago
ok but i thought the question was would it take off? .. so say your at the the point where it was at around 3:15 ish and your were to try to make the plane take off WITHOUT increasing the speed of the plane would it take off? i dont think the scenario was can a plane go across a treadmill at whatever speed its if the plane and the treadmill were matched would the plan be able to take off.
but maybe i miss understood the hypothetical situation
midgety1 1 year ago
Yeah, once you over come the friction, nothing happens. If anything, as the conveyor increases speed, you could get some airflow over the stationary plane due to "no slip condition," but that's it :P Thanks for showing this to those who thought it couldn't take off.
RoboTekno 1 year ago
@RoboTekno Well, it didn't take off...
markobgva 1 year ago
@baboonFreak11 seems to be onto something. When a person runs on a treadmill, you don't feel a breeze, you're for all purposes, stationary. Get off that tread mill and run normally, get a breeze. If a giant tread mill was rolling at 200 mph and a plane was throttled up to 200 mph as well, there would be no wing lift....right? Say it's throttled to 500 mph and the treadmill is at the same...still wouldn't have wing lift, right?
What am I missing?
FlamingoTropicalSno 1 year ago
@FlamingoTropicalSno The propulsion method. When you run on a tread mill, you are using your legs to propel yourself forward by pushing on the treadmill belt, but the belt is going the opposite direction at the same speed.
The airplane/jet propels itself against the AIR, which is totally independent of the treadmill belt. The wheels are free spinning, not pushing against the belt.
neodocneodoc 1 year ago 9
@neodocneodoc But if if the plane is stationary due to the treadmill neutralizing the plane's forward velocity, wouldn't the plane not be pushing against the air? With this in mind, the air pressure below and above the wings would stay the same, resulting in no lift...
DanielLawhon 1 year ago
@neodocneodoc
The plane propels itself "against the AIR" when it's actually flying, but when it's taking off it rolls on the ground in order to get air to flow over its wings until that flow is fast enough for the airplane to takeoff. If the plane remains stationary, no air at all will flow over its wings (on a day with calm wind), so how would it take off?
Jakareh75 1 year ago
@Jakareh75 Unbelievable. So your saying the airplane propels itself against the AIR when it is flying, which is true. What makes you think that it is different when it is on the ground? The engines are still pushing against the AIR to get it moving on the ground. If it was pushing off the ground, then the wheels would have to be powered, but the ARE NOT. The wheels are freely spinning! Movement of the ground is irrelevant.
jetengine7 1 year ago
By the way, you're also wrong about a threadmill moving in the same direction as the airplane. That would actually help it to takeoff because it would increase airspeed. The exact same principle applies to the catapults used in aircraft carriers.
Jakareh75 1 year ago
@Jakareh75 The treadmill will NOT help or stop the plane from taking off no matter what direction or speed it goes. The airplane is pushing against the AIR to move, NOT the ground. The wheels are freely spinning and only have a tiny amount of friction in their bearings. The only way to help a plane takeoff is with a headwind. To stop it from taking off, you need an enormous tailwind.
jetengine7 1 year ago
@jetengine7 Fuck, you're stupid. Planes fly because of air moving over the wings. The propeller isn't there to do that, the propeller makes the plane move forward, and the air around the plane moves over the wings. Notice how there is no movement of air on the treadmill? It's not a fucking space shuttle.
sim2lew 1 year ago
@sim2lew I never cease to be amazed by peoples' ignorance and stupidity. I never said the propeller provides the airflow over the wings. Even an idiot knows that it doesn't. The propeller provides forward thrust by pushing air backwards, because Newton's third law says for every action there is an equal and opposite reaction. So the air being forced backwards by the propeller exerts a force on the propeller blades, pulling the whole plane forward. Notice that the ground is never involved.
jetengine7 1 year ago
@jetengine7 That doesn't make the plane take off. The plane just sits there going nowhere. if the ground wasn't involved, planes all over the world would be moving at thousands of miles per hour without the engines on. That includes RC planes. Friction occurs everywhere.
sim2lew 1 year ago
@sim2lew There is only a tiny amount of friction in the wheel bearings and this friction does not change no matter how fast or how slow the wheels spin. The prop will always have to overcome the same tiny amount of friction no matter how fast the wheels are spinning.
jetengine7 1 year ago
@jetengine7 You idiot, friction becomes greater with speed. GO AND LEARN BASIC PHYSICS, MORON!
sim2lew 1 year ago
@sim2lew Really? The friction in the wheel bearings gets greater with speed? What world do you live in? Bearings have a coefficient of kinetic friction, which is constant. No matter how fast a wheel spins, the friction in the bearing STAYS THE SAME! Only certain types of friction increase with speed, such as air friction. I have a 3.96 GPA. I work with wheels, bearings, airplanes, and turbine engines daily. I know what I'm talking about. You obviously haven't understood anything I've said.
jetengine7 1 year ago
@sim2lew The reason that airplane wheels don't spin as the Earth moves underneath them is because the Earth is moving at an extremely slow and constant speed, not accelerating. This movement of the Earth is nowhere near enough to overcome the friction in the bearings. If is was significant at all, then you would feel like your feet were being pulled out from under you when you stood up, like standing in a bus while it's accelerating, braking, or turning.
jetengine7 1 year ago
@jetengine7 HAHAHA slow my arse. 700-900mph? Wait, so you're saying if you turn on the treadmill, hold the plane for a while and then let go when the wheels are turning at the treadmill speed, the little plane won't move? xD you're funny. A plane can only take off when the air pressure under the wings is greater than the pressure above. The treadmill means that the wings are stationary and the air pressures are equal. That is why the plane doesn't fly, dumbfuck. It's simple.
sim2lew 1 year ago
@sim2lew I didn't say the plane won't move when you let go of it. Of course it's going to move backwards because of the friction in the wheel bearings. I said if you increase the speed of the treadmill WHILE you're HOLDING the plane, it WON'T get any harder to hold it in place. The plane WON'T move backwards with any more force than it did when the treadmill was slower. Learn to read. The treadmill DOES NOT keep the plane in place b/c the wheels compensate for the treadmill by spinning freely!
jetengine7 1 year ago
@sim2lew It doesn't matter how fast the Earth spins. As long as it spins at a CONSTANT speed, it will overcome the inertia of an airplane and make it move with it. That's why you don't see the wheels rolling underneath parked planes with the brakes released. That's also why your car wheels don't start spinning as the Earth moves underneath them when you put your car in neutral on a level surface. On the treadmill, however, the wheels do spin underneath the plane even when the plane is stationary
jetengine7 1 year ago
@jetengine7 No, the reason planes don't move around is because the earth and air are all moving at a constant speed, and gravity keeps the planes on the ground. There is a considerable force between them. You seem to underestimate forces.
sim2lew 1 year ago
@sim2lew If the treadmill was exerting any considerable backwards force on the airplane then you wouldn't be able to hold it in place as the treadmill got faster. The treadmill will only exert its full force if the airplane's brakes are applied.
jetengine7 1 year ago
@jetengine7 It does become harder to hold. You're stupid. The backwards force doesn't disappear. It's just easy for you to overcome.
sim2lew 1 year ago
@sim2lew I'll say it again. Airplanes push against the air to move, not against the ground. Just like you push against water to swim, airplanes push against a fluid too: air. Imagine walking on a treadmill at the bottom of a pool. If you're always touching the treadmill does it make it any harder for you to swim forward. As long as your feet keep up with the treadmill like the airplane's wheels do, all you have to do is push back against the water with your hands and you will move forward.
jetengine7 1 year ago
@jetengine7 Oh, and it DOES make it harder, just not much harder.
sim2lew 1 year ago
@FlamingoTropicalSno
in your example the treadmill is going 200mph one way, and the planes thrust is pulling the plane 200mph the other way. The planes wheels are free spinning which means they would be going 400mph, but this means nothing in the plane taking off.
dv6426ca 1 year ago
@FlamingoTropicalSno you're missing the fact that you can't throttle a plane up to 200 mph. The throttle affects thrust which is a force and not a speed/velocity. Basically a real plane needs very little of its full thrust to overcome the friction of the wheels. And conveyor belt speed does not really increase that friction. At so low thrust levels the airplane would not get airborne even on solid ground.
komninosm 1 year ago
nerd
avengedcman 1 year ago
@avengedcman
troll
neodocneodoc 1 year ago 3
wow you have a lot of time on your hands lol
mi55Charlotte 1 year ago
@mi55Charlotte 5:30 seconds??? Actual setup, filming, and breakdown took about an hour...two years ago :)
neodocneodoc 1 year ago
Yes, a sailboat can go faster than the speed of the wind.
aclsalrfp 1 year ago 2
@aclsalrfp Oh boy...now you're going to confuse the naysayers with vectors ;)
neodocneodoc 1 year ago
Mythbusters next show:
The laws of physics vs. idiots.
What's next, proving that a sailboat can go faster than the speed of the wind?
aclsalrfp 1 year ago
@baboonFreak11 the plane will not remain stationary, so it will fly
neodocneodoc 1 year ago
So what's ground speed have to do with airplanes. I thought a plane used airspeed. On an aircraft carrier, they still point her into the wind for launching and recovery.
aclsalrfp 1 year ago
@aclsalrfp exactly...this is for people who believe the plane will be held stationary by a treadmill.
neodocneodoc 1 year ago
Well i guess when you take a jumbo jet that ways tons, its going to put more friction on the bearings other than styrophome and plastic. But idk you took physics so. i guess you would know more.
GamerLP14 1 year ago
@GamerLP14 you are correct...there would be more friction on the wheel bearings...absolutely. Keep in mind, though, they can also produce more thrust...like 250,000 lbs. of thrust, which would easily overcome the friction.
Remember that a jet lands between 130-160 knots (for a 747) and the 'treadmill' is effectively zero...are there any ill effects to the plane??? No. Conceptually that is the the same as the jet standing still and the treamill going 160 knots in the other direction.
neodocneodoc 1 year ago
this join ass!!!!! like get to the fuckin point
shakieer45 1 year ago
@shakieer45 I don't understand the language that you are speaking. Must be trollspeak...is "join ass" a good or bad thing?
neodocneodoc 1 year ago
@neodocneodoc By the sound of "Join Ass" I don't think any of us, or you would want to know.
TheAninimouse 1 year ago
no one cares about your stupid tecie talk just get to the stupid point
btw what is the friken point of this
Judenc62 1 year ago
@Judenc62 apparently 62,000 people were interested.
I don't think anyone is interested in your troll.
neodocneodoc 1 year ago
I understand this. I understand that if a plane was on a treadmill it would be able to overcome the speed and take off, what bothers me is If you were to match the speed perfectly so the plane is stationary as the treadmill rolls and you had a plane with flaps....it wouldn't take off standing stationary. There wouldn't be any airflow to create the lift through the wings. Thats what drove me crazy about the mythbusters episode.
kalloused 1 year ago
I dont even think i get the conundrum. What does the power of the wheels have anything to do with wind hitting the planes wings? The air aorund the tradmill will be moving at 0mph (in a vaccum :P ) and obviously not produce lift even if the treadmill was going 3240987 mph. I dont get it.
novahcac 1 year ago
@novahcac The question is stated as though the treadmill would hold the plane in the same position relative to the air. The treadmill will be unable to keep the plane stationary relative to the air (since it is propelled with air movement, not force to the wheels), so the plane will continue to move forward relative to the air, achieve lift, and take off.
neodocneodoc 1 year ago
@neodocneodoc In the case of a real plane whose wheels have nothing to do with its propulsion, and neither does the speed of the wheels' movement, Why isnt it obvious to everyone ever that the only thing that matters is the speed of the plane relative to the wind around it? Who cares about a treadmill, all it will do is move the wheels. If they are 'perfectly greased' theoretically the plane should stay in one spot, and with any propulsion it would move forward. I still don't see the conundrum.
novahcac 1 year ago
@novahcac I agree...I don't know why people have difficulty grasping the concept.
neodocneodoc 1 year ago
Real planes only use their wheels to roll, they don't drive the plane. The plane's engines are what drive it, RC planes don't just use their wheels to roll.
rossidude 1 year ago
@rossidude ??? This is a prop plane on a matchbox car.
neodocneodoc 1 year ago
No. What is happening is, you've become so attached to your own creation that you can't entertain there are ground speed viewpoints and airspeed viewpoints. You will insist on no ambiquities. You've walked into a well worded conundrum. Admit it. It's the first step to recovery :) Three times you've put words in my mouth and and negated your own thinking. You've even demanded I Stop thinking any way but yours, lol. That's uninteresting. Good luck with your world. Thanks for playing.
MsSimplegreen 1 year ago
@MsSimplegreen this isn't a special relativity question. I posted the question I was basing my experiment on...I did not put words in your mouth once. I did not negate my own thinking. I never demanded that you stop thinking any way you want. I just asked for a free body diagram and math...that is all. But since you feel it is a conundrum, you refuse. To each their own.
You are a woman, aren't you?
neodocneodoc 1 year ago
really who gives a fricking shit
carg98 1 year ago
@carg98 exactly
neodocneodoc 1 year ago
Third, you may try to 'squeek' around the logic by posing that the plane possibly has a prop wash strong enough to cause vertical lift flowing by the wings (prop forward). A "Plane", however, would mean "most" planes and most planes can't hang by the prop and go vertical. So that would be a semantic attempt at a solution, not a solution. But hey, why not? We've already got an imaginary infinite treadmill. "Plane v Treadmill Solved!"? Chuckle.
Sconz32 has it, "You don't understand the premise."
MsSimplegreen 1 year ago
Second, "the treadmill can do nothing to keep the plane from moving forward". Um, No Sir. Thinking you "get it" when you visualize the wheels aren't the supplied power but the prop is, doesn't negate the premise of a magical treadmill that can always be faster than the plane can go forward. Matched speed, no forward motion, no lift. One could also mix the real with the imaginary in the reverse by, "Try running on a 30 mph treadmill". At some point, a real world wheel bearing will burn up.
MsSimplegreen 1 year ago
All you "prove" is that with a LIMITED speed treadmill, you can overcome it with the throttle. The original wording says the treadmill can ALWAYS match the plane. FINITE plane, INFINITE treadmill. Get it? You're imagining this treadmill running even super fast and the plane's wheels matching it, but the friction being small, lets the plane surge forward and zoom off into the sunset, lol. However, the planes prop power has a limit, the treadmill doesn't. This is the myth 70NYD tried to point out.
MsSimplegreen 1 year ago
Sorry, but it's a FAIL. First, it's a stupid argument. Set up and no doubt still laughing by the originator. An unlimited and Theoretical infinite speed treadmill is mixed with real world mechanics of a prop plane on wheels. You fell for this first conundrum (unanswerable), not the people trying to point out the several falacies to you.
The fact that the rolling friction of the wheels, is miniscule compared to the power of the prop to move the plane forward can't be used. It's Finite.
MsSimplegreen 1 year ago
@MsSimplegreen Show me your bearing data...I showed mine (somewhere in here)...do you know how low friction wheel bearings are? Next time you are in a car, see how far you will roll in neutral. Miles.
The plane will move forward, and my argument CAN be used. Doesn't matter if the treadmill has 'infinite speed'...the treadmill matches the planes forward speed, but in the opposite direction...not blast to infinity to try to keep it from moving.
neodocneodoc 1 year ago
@neodocneodoc Bearing data? Unnecessary tangent. Clearly I used your givens. Friction low, thrust main factor. The premise mixes impossible (unlimited treadmill) with real world (plane). So viewpoint determines solution. If you still pursue it, the Crux is, that the treadmill can always be advanced to nuetralize planes forward motion because planes power is Finite, the treadmill has no limits. You Matched planes speed to treadmill before, plane going forward is a mismatch. Treadmill is slower.
MsSimplegreen 1 year ago
@MsSimplegreen ORIGINAL QUESTION:
A plane is on a runway that is a giant conveyor belt. As the plane moves, the conveyor will exactly match that speed but in the reverse direction.
Can the plane take off?
neodocneodoc 1 year ago
@neodocneodoc Real plane on real runway; 2 foot round wheel Must move forward 2 feet, again and again, creating apparent wind for lift. Whether the thrust is a prop, jet engine or atlas booster it has a Finite limit. Everytime plane rolls wheel forward 2 feet, the no limit treadmill can counteract that 2 feet. That is Matching the speed of plane with treadmill. Infinite treadmill can match any plane's speed, up to burning up the wheels. Would also negate liftoff btw. Keep thinking, you're close.
MsSimplegreen 1 year ago
@MsSimplegreen ORIGINAL QUESTION:
A plane is on a runway that is a giant conveyor belt. As the plane moves, the conveyor will exactly match that speed but in the reverse direction.
Can the plane take off?
neodocneodoc 1 year ago
@MsSimplegreen The question was not whether the treadmill can move fast enough to keep the plane stationary. The question talks about MATCHING speed. The plane goes forward at 5 knots, the treadmill goes in the opposite direction at 5 knots....not 500 knots to keep it stationary. Don't modify the question to make it fit your answer.
neodocneodoc 1 year ago
@neodocneodoc If the treadmill indeed matches the planes speed, it will be stationary. Stop misinterpreting the premise to fit yours :) The speed is relative to the observer, not the plane.
MsSimplegreen 1 year ago
@MsSimplegreen Plane = 50 knots
Treadmill = 50 knots other direction (measured linear belt speed)
Plane moves forward and takes off.
neodocneodoc 1 year ago
@neodocneodoc It's a Conundrum.No answer. The originator mixed the Real, the Unreal, and semantics and likely didn't take a side. It's for fun. All the mech, physics, geometry formulas won't solve it. Why? Real world formulas don't mix with semantics. If you decide to go down the rabbit hole, fine. Just know switching to the impossible (unlimited treadmill) or to real world data can disprove a chosen position. *Match* is parsed. Sconz32, "You don't understand the premise of the argument"
MsSimplegreen 1 year ago
@MsSimplegreen That is your argument because you don't understand the point of the original question. Sigh.
Show me your free body diagram and your math. No calculus should be required
neodocneodoc 1 year ago
@neodocneodoc Because Liftoff *is* the goal, it *does* imply if the plane can be kept stationary. That's the whole point. Saying "wheels don't matter or once a given plane speed happens the belt must maintain it and added power makes it lift off" is a misinterpretation. Wheels matter. Put 747 on revolving runway, held by a cable. Runway to 400mph, uncable. See, plane doesn't move! Oh wait, minutes later it creeps backwards increasingly. Reverse also true. Runway, via wheels can nuetralize it.
MsSimplegreen 1 year ago
@MsSimplegreen As i say in the video (I believe..it has been years) the ONLY force that the treadmill will provide is the rolling friction that it creates by the added rotational speed of the wheels...that is it.
Show me your free body diagram and your math (feel free to plug in the bearing data values...you will need them) and show me how a treadmill going the opposite direction AT THE SAME SPEED will keep it from moving forward
The question wasn't CAN a treadmill keep it from taking off.
neodocneodoc 1 year ago
@neodocneodoc You know, either way, it didnt work. :)
mancreep 1 year ago
fantastic :) i think i finally 'get this' now, cheers.
alexkidd3d 1 year ago
Can there be sufficient airflow going over and under the wings to produce lift if it is not actually moving through space? I don't know. It depends on whether the conveyor moves the air along towards the plane.
Muffinfordinner 1 year ago