Added: 4 years ago
From: kmorgan26
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  • Not all airplanes are self powered. A glider is an airplane. Put the glider and it's tow vehicle on the treadmill and you are still doing the experiment correctly, as described in the so-called myth. Try ALL possibilities and you will see that all arguments related to this "myth" can be shown to be correct (both fly and no-fly) - it just depends on what assumptions you make. "This is how things work on earth.." - again - an assumption, but atmoshperic conditions are not mentioned in the "myth".

  • @RCbeastly You are introducing variables that were not intended as part of the puzzle. If you are going to introduce things at random, should I consider also that the person in the plane isn't a pilot? Should I consider if the plane might be made of paper machete? Maybe the pilot dies 3 seconds into the takeoff procedure...

  • @kmorgan26 That's the whole problem. I don't subscribet o either fly or no-fly view because I can argue either case depending on what assumptions I make. There is simply not enough detail in the myth to lead to ANY conclusion without making assumptions. You yourself have fallen into the trap by assuming you know what was "intended as part of the puzzle". Simply take the known data from the myth and only extrapolate those things that can be. Don't make ANY assumptions.

  • @RCbeastly If you want to make shit up you can argue that we live on Mars depending on what we call the planet we reside on. The plane can take off from a moving surface if it's moving toward or away from the plane. Bottom line.

  • @kmorgan26 Make shit up? The definition of airplane includes gliders. Try again, using a glider. You always seem to assume the airplane is powered. When a car is on the belt, it's speed is measured in relation to the belt. This is why the no-fly's measure it this way with the 'plane. The fly's measure it in relation to the air, which is changing the point of reference. I do see both points of view, but the myth is too general to allow a conclusion to be reached without any assumptions.

  • @RCbeastly Maybe the conveyor is lined with really, really strong magnets. Maybe the conveyor is made of peanut butter. How would it spin then? Maybe the plane is made of macaroni and cheese. Good luck getting that off the ground! Maybe the pilot is a chipmunk. He can't fly! The puzzle doesn't discount any of these things!

    These are about as stupid as the items you present. I understand this puzzle. If you can see "both points of view" then you don't get it. It's really that simple.

  • @RCbeastly

    you should watch all his videos, they are funny

  • I can't believe this is even a debate. It's utterly ridiculous. Put simply, planes gain lift from the large amounts of air they force under their wings as they move. You put one on a belt going in the opposite direction and you remove the air passing the wings, thus you remove the lift. Mythbusters did the test wrong, since the plane still moved forward, so of course it took off.

    The speed of the engine is irrelevant. It's all about the speed the plane moves through the air.

  • @UnknownSquid I'm sorry, but you don't understand this puzzle or the concept of lift. The low pressure caused by air OVER the wing as opposed to the air under it is what creates lift, not the AMOUNT under the wing...but that's another topic.

    The conveyor belt will NOT stop the plane from moving forward. The plane moves forward because it doesn't need wheels to propel it forward. You should watch some of my other vids on this topic.

  • @kmorgan26 Are you sure you understood the question?

  • @RCbeastly yep.

  • The funny thing is, people who argue that the plane can't take off are really arguing that planes can't fly at all (although they don't realize it). If the speed of the earth against the wheel could in any way affect it's ability to take off then in theory once it did take off it it would fall to the ground again because apparently the wheels need to push against something to fly. Don't even ask how floatplanes work. I think it has something to do with water pressure and the CIA.

  • @Str8pipedRanger I'm going to make another video about this. I love this puzzle. I'll probably make it tonight.

  • Well said. Consider this scenario if it helps someone get their head around this. A car on ice spins its wheels but doesn't go anywhere (not unlike the treadmill situation). Now, put a plane on ice and hit the throttle and it moves forward and takes off just like it would on a runway. Why does it not just spin it's wheels like the car? Because it's not using the tires grip to push it over the ground. It's using the propeller to pull it through the air.

  • you got it.

  • The experiment is misleading then.

    I understood it as the conveyor belt moves backwards, the pilot would create enough thrust to keep the plane in the same spot. Obviously the plane would never take off.

    If the experiment said that the plane is allowed to move forward and reach take off speed whilst on a reverse treadmill, obviously the plane would take off, the treadmill might as well not be there.

  • Your mistake here is that you assume that the pilot would need any significant thrust to keep the plane in the same spot. The wheels spin freely (nearly), so little to no thrust is needed. Once the pilot applies thrust (which is applied to the air not the ground) the condition of the ground surface is close to insignificant.

  • If the plane produced no forward thrust on the treadmill it will travel backwards, accelerating until it reaches a certain speed, less than the treadmill because of wind resistance. If the plane then produced enough thrust to stop going backwards but remain stationary then it will decelerate until it stops and would not lift off of course.

    The answers are obvious,. It depends on your perspective what this flawed experiment

  • What you are not understanding here is that the wheels of an airplane are "free spinning". The only thrust the plane has to have to overcome the treadmill is the friction of the bearings of the wheels and some minimal suface friction. An airplane is NOT a CAR with wings.

    The results you are describing is what would happen if a CAR was on a treadmill since the drivetrain of a car is setup to power it via the wheels. Planes are not.

    Think this through. You are WRONG. It's not flawed.

  • Maybe it's my lateral thinking here. I get completely what you're describing, it's not rocket science, just basic laws of motion.

    My point in previous post is that static inertia can be overcome. Pull a table cloth quickly and the plates will stay on the table, accelerate it slowly and the plates will travel with the cloth.

    Yes the wheels are free to spin but if you start the treadmill slowly so it doesn't overcome the static friction the plane will move backwards, if it produces no thrust.

  • @PorkyPiggles

    your not wrong at all

    Mythbuster said the plane is going to stay still. Thats the experiment.

    We already know planes take off from aircraft carriers. So why would they reproduce that experiment ?

  • @taledarkside the plane won't stay still...and Mythbusters didn't say it would either.

  • @kmorgan26

    mythbusters said, will the plane fly.

    If you watch the first experiment, where they have it on a jogging treadmill, the plane never flies.

  • @taledarkside I don't care what experiments Mythbusters did. The fact of the matter is, an airplane would take off from a treadmill. If you don't agree, that's OK. It just means you don't understand how airplanes work.

  • @kmorgan26

    I'm a pilot plus I have a bachelors in Science.

    The whole point of airplane on a treadmill is because mythbusters brought it up.

    A plane will NEVER take off from a treadmill if there isn't a pressure difference of the airfoil. Something for you, air going past the wings that will have a large amount of pressure to cause lift. 

  • @kmorgan26

    Plane can have no thrust and take off from a treadmill. You can have a plane with its engine off and parked, will it take off from a treadmill, because you say so?

    What if you have a glider on a treadmill? will it take off too? its an airplane. according to you, if a plane is on a treadmill, it will automaticaly take off.

  • Good explanation. And totally correct.

  • You mentioned in your comment..."the plane doesn't actually GO anywhere."

    Yet in my video, I explained that this isn't the case. They plane WOULD go forward on the treadmill. That's the misunderstanding.

  • Why don't they use this method on air craft carriers then? There's a difference between the fan force that drives the plane on the runway to the forces that give it lift.

    As soon as its moving forward its going faster then the conveyor.

  • This method isn't used on carriers because it would make no difference.

  • haha touce! :)

  • Apparent wind speed is required for flight.

    Learn to aerodynamics.

  • I'm right. The plane flies.

  • Did you get a haircut?

  • Hey man, great videos you have.

    I think distinctions should be made on no force vs. negligible with regards to the tires. ACCELERATING rotation does cause a backwards force. Hold onto a rope on a treadmill with roller blades on, while the belt speeds up and you can feel this effect.

    However, the effect is effectively proportional to the mass of the wheels and the airplane, which compared to the wheels is orders of magnitude larger and why we would never see this effect on a real world plane.

  • The speed of the treadmill doesn't matter, but the acceleration DOES. If the acceleration of the treadmill is sufficiently high (equal to the thrust/m) then it can always overcome the plane's forward acceleration.

    The plane will only take off if the wheel SLIPS (doesn't roll) or the velocity of the track doesn't "keep up" with the velocity of the increasing velocity of the plane

  • Sorry, but you are wrong. As I mentioned in the video, the plane uses the air to take off. The treadmill can be accelerating 2, 3, 4 times that of the plane...doesn't matter.

    What if the wheels of the plane, in flight...were spinning backward 4 times as fast as the plane? Would it crash? The wheels don't need to grip anything to fly or take-off. They are free-spinning, and do not power the plane at all.

  • No -- they are not free-spinning, they are rolling. The wheels have static friction which grip the track.

    The Wheels spinning in the air would be as if the wheels were skidding -- as in, they slipped across the ground and did not spin. That is what would happen on frictionless ice, but not a runway/track.

  • You're wrong. Sorry. The wheels on an airplane are not connected to a drive train...and they don't have to grip the road for the plane to move forward like a car does. A plane is not a car with wings. A car's wheels need to grip the road to move because they are connected to the cars power source...the engine. The wheels of a plane are not. The engine(s) of a plane apply power to the air, not the ground.

  • The wheels aren't powered, but they do grip the road like a car does. That means they rotate, they have an angular acceleration, and as a result they exert a linear acceleration on the plane. This is the setup as you explain it: Initially (t=0): Vtreadmill = -5mph Vplane = 5mph Net speed = 0mph At t=1 second: Vtreadmill = -5mph Vplane = 8mph Net speed = 3 mph <-- the plane is moving forward relative to ground. Don't you see that this is obviously a violation of the problem statement?
  • This is where you go wrong. No, an airplanes wheels don't grip the road "like a car does." The car is required to grip the road to accelerate. A plane is not. The only thing the treadmill does in this case is make the wheels spin faster. It does not prevent forward motion, since the force of the prop/turbine is applied on the air. You have to get it out of your mind that the plane accelerates by gripping the road/runway. Picture a plane tethered to a truck in front of the treadmill. (cont.)

  • ...the treadmill can spin as fast as it wants, since the plane is tied to the truck. It will remain stationary. Now, put the truck in gear, and drive away. The plane moves forward, and the wheels spin as fast as they were before, PLUS the speed of the truck. The force is independent of the wheels by the rope and truck...just like it is in the case of the prop against the air. The plane will move forward at the same speed as the truck, and the treadmill can spin as fast as it wants.

  • Check PM.

  • That's an excellent analogy! you'd hope people will now understand! :)

  • You just made me understand this... thanks!

  • haha, well im glad you explained it. i was watching this and my dad saw it (hes a private pilot) and he was like "NOOOO THATS NOT RIGHT!" so im glad you cleared that up.

  • I get it now, thanks!

  • "'Cause that's the way things work here on earth..." Haha. And thanks, I understand it now :]

  • Great video!! What is your line of work?

  • I am a retired Army guy. I was in Aviation, but not an aviator. Presently, I am doing web-app development.

  • Oh ok. I am an Aircraft Maintenance technician and just wondering because you have some knowledge about aircraft. Amazing people don't understand this stuff huh!?

  • Oh why people have to express their opinions about this matter when they have zero knowledge of basic physical facts, its human nature i guess..

    Good try for trying to explain this myth to those kind of people. Hope some GET IT. :)

  • I think I get it, if a plane were to attempt flight using its wheels, it wouldn't last long because wheels can't grip air and push it behind them to create thrust, propellers can.

  • great explanation.

  • You are of course correct. But it is also true, if, due to sufficient rolling friction and increasing belt speed, the plane could be maintained stationary with respect to the ground and the air, it would NOT take off.

  • umm a plane goes forward by using the propellor, ok i knew that, but doesnt it need to accelerate so that air will lift the wings up. i dnt think that it should manage to accelarate , or not as efficiently as with normal ground, at first it should be not moving.

  • You have the false impression of what will happen just like I explain in the video. The plane would not have a difficult time moving forward in the least.

  • Thank you.

    It's really funny to me that people don't get this. Sailing is how many years old? These principles are the basics of sailing, it's not rocket science people. Just listen to the man.

  • No there's a difference: in sailing the ship "slips" through the water which is moving at a constant velocity. When the wheels roll for the plane case, their tangential velocity must equal the linear velocity of the belt. If the belt was accelerating, the wheels must also have angular acceleration (based on inertia), and in a no-slip condition this results in the wheel's (and hence the entire plane's) change in linear velocity. If the belt accel = plane's accel, the plane will not move.

  • I cant imagine people thinking that the speed of the wheels would effect the speed of air over the plane wings ..its not powered by the wheels!!!

  • your all idiots its the wind over the air pfoil of the wing the motor dosnt make it take of it pulls it threw the air its tha air thats importent not the ground

  • It's you're, not your. It's through, not threw. It's the, not tha. It's that's, not thats. It's important, not importent. I think it's 'plane' to see you are the idiot.

  • You forgot "its" instead of "it's" and "dosnt" instead of "doesn't" and my favorite, "air pfoil" when "airfoil" would have been more appropriate.

  • Thank you for the video. I got a question though.

    Would a plane powered by jet engines take off? Say for example a Boeing.

  • Yes it would, since the plane is still powered by something other than the wheels, as are all planes.

  • thanks for the video. The last point you made was the point I was going to make if you didn't. I was simply going to say that IF you put an auxillary engine connected to the wheels to move the plane forward, without the propoller spinning, then it WOULD BE a VALID test. However, the way the test is setup now contradicts physics and airplane theory. thanks again!

  • how does an airplane get any lift if it isn't moving?

  • How did your comment get posted if you never typed?

  • HAHAHA

  • If the plane wasn't moving (relative to the surrounding air - you could as well put a huge ventilator in front of it), then of course there would be no air flow over the wings and hence no lift and no chance for the plane to take off.

    But the plane IS moving (as you can see in the Mythbusters vid that this vis responds to) and hence there's the necessary air flow over the wings.

  • Why? The propeller pulls the plane forward, no matter what happens beneath it to the wheels. The propeller doesn't need the wheels to do anything - not on the ground and not in the air. (The plane only needs the wheels so that it doesn't have to slide on its belly.)

  • Unmount the wheels and put the plane on skates and let it try to take off of a frozen lake. Works just as well. Or think of a hydroplane that can take off of water. Or hold an RC plane in your hand and rev the propeller: you'll feel the plane pulling. Or think of any plane that is in mid air: there's no runway, no wheels involved - and the plane can still accelerate with the thrust that the propeller generates.

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