@@zacharyclownphobic2316 I will probably maybe never not forget your smiliey face comment, this is the best thing that has ever happened to me in my entire life and i will named my first born child after you if a women ever lets me near her front butt
@@bebophippie1781 and did stint at unofficial star-trek, TOS, the play Solu the pilot too until it was closed down; competing to must with GG star-trek with wasn't that hard, the end of the test card signel screen was doing better GG star trek at the time.
I finally understand it, the wheels of the plane are just spinning twice as fast. the plane is still going to pull forward no mater how fast the wheels are already spinning on a treadmill. It'll work every time unless a wheel fails or something. The force of the propeller won't allow the plan to just set there. Its pulling on the air, not just the ground. Wow, it finally makes sense now. I remember watching this on TV when it aired and I wasn't satisfied with the experiment because I thought they didn't match the speeds.
Interestingly, you could actually argue that they _didn't_ match speeds. The question is poorly defined, leading to multiple possible interpretations of what "matching speeds" means, and in one of them, it's actually physically impossible to do if the plane is moving. (If you're curious about the details, xkcd has a page on it.) By that interpretation, _Mythbusters_ should've tested this by bolting chocks to the runway so the plane's wheels couldn't move forward or back. Also, I made the same logic error you did. Nice to know I'm not alone. 😊
Let me try to understand this. If there were no rolling resistance in the wheels, the plane would stay in-place on the moving treadmill (stationary to the surrounding terrain) while the planes engine is completely powered down. You can test this by placing a Hot Wheels car on a sheet of paper, and pulling the paper backwards. It is the same as the trick where you whip away a tablecloth and all the plates stay in place. Like the tablecloth and plates, the rolling resistance of the wheels is very low once the initial friction is overcome. Up to this point, all the energy spinning the planes wheels comes from the treadmill. For a plane to achieve lift, it's all about airspeed, so it's irrelevant if the wheels are spinning. In fact, a plane can lift off from stationary without an engine if there is enough headwind. On the treadmill, the rolling in-place plane has zero airspeed. Once you add energy in the form of the engine turning the propeller, this balance will be overcome, and the plane will gain airspeed at the usual rate.
It’s not that the wheels spin twice as fast lol. It’s because on ground, in a car, your engine drives the wheels. In a plane, the propeller pulls the entire craft forward, the wheels are going to spin on the ground (as long as the ground touches the wheels) as fast as they need to because the propeller is pulling the whole craft. They put a toy car on a treadmill and push it, that’s a good way to picture what forces are in play
They clocked the plane's takeoff speed as 25mph prior to taking off on the conveyor belt, which they set for 25mph in the opposite direction. They should have put a speedometer on the wheels, as that should have indicated takeoff would have happened at 50mph wheel rotation speed which I think is the point they were trying to make! They didn't say if the plane took off at 25mph as recorded on the pitot tube (airspeed) and what distance it took off at relative to the non-conveyor belt distance. It's a bit frustrating that they didn't conclude with the math which should have revealed a lot. I suspect the conveyor belt itself had some minor effect on the direction and speed of the air, but that's what determines if a plane takes off or not-- the airspeed, not the groundspeed. If you chocked the plane from rolling back and blasted air at the plane from the front at takeoff speed, it should lift off from the ground from that static position, even with the engine turned off.
yes, very good. and I am REALLY surprised the pilot did not know better since for flying there is literally airspeed and groundspeed, and its the airspeed that all flying is done by. this takes a role in every start and landing, for example with wind...
Thank you for uploading this and all other episodes. Hopefully these entertain and teach people for centuries... or at least some decades more. Regarding the plane myth, I think the controversy will always be born from focusing more on the setup that the physics facts: A plane flies because (as the lift formula tells you) it's got a wing designed to create lift higher than its weight at X speed. The problem with the setup of the myth is that it never specifies whether the plane should match the speed of the conveyor, because otherwise it'd be stupid simple: if the plane is supposed to remain stationary like the car did, it'll never take off, no matter the speeds involved so long as the net is zero. If the plane is allowed to develop its own speed taking the net above zero, it just needs to go fast enough to generate lift, and it'll always take off if it reaches that speed. It's a stupidly simple thought experiment, that only becomes complex and confusing when you try to put it in practice.
The plane on the conveyer belt works because the wheels are free moving and not providing any sort of drag. The plane takes off because the propeller provides the thrust and moves the plane using the air as its medium. The wheels are still just free moving, unlike a car. Now a plane flying against fan blowing against it, that's different.
Yeah, but there is downward force from weight as well as friction from the tires. This myth's conclusion assumes none of that exists, which makes the whole thing silly nonsense, because that's the part that interacts with the conveyor, which is what the whole thing is about....
@@Cuzzzo42 There is, but it's nowhere near enough to offset the thrust of the engine or the lift from the wings. Planes ultimately don't weigh very much for their size, or they wouldn't fly at all. You're basically never going to, in real life, be able to create enough drag to prevent some amount of forward motion relative to the air and therefore lift, since the wheels have no resistance of their own from a driveshaft or anything. The lift also starts removing the weight on the wheels and therefore the drag they cause, so it quickly becomes a feedback loop where the plane will take off. In the purely hypothetical situation where the conveyor is actually capable of producing the drag necessary to keep the plane stationary relative to the air, then it wouldn't take off. It's just not feasible to create that situation with a belt in particular.
The easiest way to understand the airplane on a conveyor problem and why the plane will always take off is this: Attach a rope to a wall and put a treadmill in front of it. Put roller blades or skates on your feet and stand on the treadmill. It does not matter how fast the treadmill moves, you will always be able to pull yourself forward with the rope. The rope represents the thrust of the engines of the airplane. It doesn't matter what the wheels on your roller blades are doing, you can still pull yourself forward. The wheels on your roller blades AND the wheels on an airplane are free wheeling. They aren't attached to a motor or anything, so as the treadmill changes speed, it will change the wheel speed, of course, but it has no effect whatsoever on the airplane's forward movement, which is wholly provided by the engines.
You don't need a conveyor belt. Around 1984, our airplane (N51305) was on tie downs at the Mojave Airport. My biological father got a call from the tower. Our airplane was hovering in the wind trying to take off. No propeller running, no forward motion of the airplane. Just good ol' fashion wind.
That's a different situation from the myth though. The myth is about the ground moving in opposition to the plane, not the air. The plane would take off in both cases, but they're still fundamentally different situations. So it wouldn't be a valid way to test this particular myth.
@@MichaelDavis-zu2ko It kind of does relate, if you look at it from a 90 degree angle. Single engine STOL aircraft prove this to be a non-issue. What gets the plane in the air is air moving over the wing, not the plane moving across the ground. As long as the wheel bearings reduce the friction of rolling the wheel across the ground to a point that just the prop can get it up to take-off speed, it takes off. If you manage to get the conveyor moving fast enough to overcome the wheel bearings, the plane can't get up to take-off speed. (That and the tires would probably melt...)
@ I never said that it’s the plane moving over the ground that gives it lift. That’s obviously not true. I’m just saying that, for the sake of the experiment, it’s not the same to test lifting off while stationary to the ground with wind vs testing taking off while the ground is moving but not the air. The myth specifically calls for the ground to be moving backwards, that’s the whole premise of the myth. If you don’t test that, then you didn’t test the myth.
The biggest surprise in this episode is the surprised pilot. If you hold a pilot license, you should know something about thrust, drag, airfoil, and generally the physics behind keeping an airplane in the air. But apparently not.
I suspect he said what he did just to heighten the "suspense." If he really thought he would not get airborne, then he really was clueless how planes work.
To be fair, he's an ultralight pilot, which generally has laxer licensing requirements. My father used to fly ultralights legally without any license, but given that was thirty years ago and in New Jersey, I don't want to say the pilot might not be licensed at all more then a decade later and in California, but he might well not have a full single-engine certification.
@@tildessmoo Despite them calling it an "ultralight", the pilot said it weighed 400 lbs (146 lbs heavier than the FAR Part 103 limit), the tower called it a Light Sport (a FAA-certified category of aircraft requiring a license to operate), and there was an N-number registration on the aircraft (only required on certified aircraft, not ultralights).
Yeah but how would any pilot really know this until it was tested. There would be no precedent to go off of. Anything that they would've "known" about this phenomenon would have been theoretical anyways wouldn't it?
If you think they did the plane on a conveyor belt experiment wrong, read this comment (or actually watch the video, around 21:45). The reason "can a plane on a conveyor belt take off" is so controversial is because it's a poorly formulated question. It contains an implicit assumption for most laypeople - that the plane is not moving relative to its environment - but that assumption is inaccurate. If the question was asking, "Can a plane take off while stationary relative to the air around it?" the answer is obviously no. But that's not the question being asked. The myth is that the plane can take off on a treadmill and because a plane's wheels spin freely and it's the propeller that moves the plane forward, the plane can move forward no matter how fast the treadmill is moving in the opposite direction, and therefore it can take off.
Yep. There's a hypothetical situation where the conveyor could be moving fast enough to create a drag/friction vector opposing the thrust vector large enough to cancel it out, but the belt would be needing to move at basically supersonic speeds. It's not realistically feasible, and it's certainly not when the belt is moving at takeoff speeds. And such a conveyor would likely move the air above it, providing some headwind and lift all by itself.
For me, it was always simple. The plane does not derive locomotion from it's wheels but it's propeller screwing it's way through a fluid - in this case, air. The wheels are simply a method to reduce the friction.
Veritasium made a similar video called "Risking My Life To Settle A Physics Debate". The premise is slightly different, but this question makes me think about it. Xyla Foxlin also made a video too called "Building the Vehicle Physicists Called Impossible (feat. Veritasium)"
I think the controversy in the airplane on the conveyor belt myth is all due to the two interpretations: 1, as seen here - the conveyor belt moves backwards at a fixed speed equal to the takeoff speed of the plane. Result - airplane takes off normally, but its wheels spin two times faster than normal. 2 - the conveyor belt can speed up to an unlimited speed to keep the airplane in the same place with respect to the air. Assumptions: wheels have perfect traction and can spin at infinite speed, conveyor generates no airflow on its own. Result - plane remains stationary generating its full thrust, but most likely doesn't fly, as the airflow from its propeller or other engine is not normally directed over the wings, and its wings do not move with respect to the ambient air. There can be exceptions, as some airplanes do have overpowered engines mounted right above the wings, intentionally to shorten the takeoff path (like the Custer Channel Wing). They are not intentionally generating additional backwards thrust away away from the wings to avoid moving forwards, but if they did they would take off vertically in a rather uneconomical way (would be a lot easier to just blow the air down like a normal VTOL).
Yes! When I first heard the premise, my mind pictured interpretation #2. Plane stationary, no flight. It seemed so obvious that I was about to pause to try to figure out the catch. Then I saw the propeller, and I was like... oh...well yea, of course it'll fly. The wheels spin freely. They're irrelevant and so is the conveyor belt. This reminds me of one of those ambiguous riddles that technically has more than one answer because the question was poorly worded. I suspect they knew this too, but felt like it was worth filming just for fun. Or to troll us. Idk, interpretation issues kind of annoy me. I also zoned out a bit with the bug stuff. Not completely terrible, but not one of my favorite episodes. I think I'd actually prefer the Pirate Adam one 😬
Might be misunderstanding, but for the 2nd scenario, we already know the wheels are a red herring, so just chain the plane to the ground and see if it takes off.... surely there's no contention over how that turns out
@@litarea 2nd interpretation is exactly what I imagined they were testing for. Flatten the plane and the conveyor belt to a 2D X-Y graph with the plane sitting on the x axis and the y axis being the front of the conveyor belt, if the plane is required to maintain it's position on the x axis while the treadmill is on, will the plane be able to take off?
If the belt could just keep spinning faster and faster it would probably pull in enough air to push the plane up :) Which would of course then come down very fast after moving away from that air current.
I feel so bad for Jamie. You could tell from the beginning that he was frustrated about having to do this myth by the way he acts and talks. He rarely ever expresses sarcasm but did so when the RC plane left the treadmill, and he was easily irked when he couldn't keep it on the paper conveyer belt. Good for him for sticking with it and doing the episode though; hopefully it finally silenced all those silly doubters!
Unfortunately, I don’t think it will silence doubters. :) The fact that plane moved forward along the treadmill tells us that speed of treadmill is not the same as speed of the plane, what is the main requirement of the myth.
Good thing the treadmill doesn’t impact airflow! The aircraft moves due to thrust from the power plant. In a car, the tires produce the forward thrust for the vehicle. In the plane, the tires are simply there to roll. Thus, thrust is still produced and the aircraft still moves forward, and still gets airflow over the wings, and still takes off.
@@aao_fox9387 This is correct, and so many people get it wrong. The plane will always fly because the FUSELAGE is what is being pulled through the air by the power plant, regardless if it is a piston engine or a jet engine. The wheels will just spin and spin against the conveyor, but the plane will move forward. The problem comes from the misunderstanding about how an airplane does its takeoff roll. It has nothing to do with the wheels providing anything other than a platform for the airplane to roll on.
It’s absolutely insane to me that this originally aired in 06…. 2006! I was 5 years old lol… you guys have been legends for so long now, I can only wish to even be half as cool as yall one day
truw but thats's not even the reason for this it';s just the simple fact that the wheels spin twice as fast and the plane more or less doesn't even notice
@@ghostrunner2138 Which is what people dont understand from this being even considered a myth. People even to this day say that even Jet engined planes wouldnt be able to take off, as if the speed the wheels spin has any impact on the forward momentum of the plane.
I love Mythbusters. Thanks for showing people that "treadmill airplane" is just stupid. No airspeed means no lift means that you just sit with the engines running... What are the wings for? Airspeed equals lift... Hello? J. (pilot from Michigan)
The plane was still moving forward. The idea was for the plane to stay put with the Throttle Maxed Out. This is essentially just the equivalent of Taking Off With The Wind. You just have to go a little faster than usual to compensate. But it’s not Ideal, not to mention Highly Inefficient. It doesn’t matter how fast the Propellers are Spinning. Air needs to be hitting the Wings at a certain Speed at the right Angle Of Attack in order to Generate Lyft.
For anyone looking for a summary of the "controversy" around the airplane myth, I'll provide my current understanding of the big picture. Unfortunately, this episode didn't help because it added ambiguity to the exact conditions being tested. IF the myth was exactly what was tested on the show -- a free-wheeling airplane can or cannot take off on a conveyor belt -- there would be no contention. There is a fairly universal understanding that planes don't move forward on a runway thanks to an engine powering their WHEELS, but rather some air-moving device (propeller, turbine) throwing air back in order to move the body of the plane forward. Same thing is a lot more obvious on seaplanes, which have skids instead of wheels. The DEBATED version of the myth is: if an airplane CANNOT MOVE FORWARD RELATIVE TO THE GROUND, can it still take off? There are 2 commonly-held levels of understanding that determine which side of the debate you fall on. The first understanding is limited to the fact that planes take off (and stay up, thankfully) thanks to a force called "lift" that is generated when air moves past the wings at a high speed. The question then becomes, how do you GET air moving past the wings? The clear answer is to move forward, which would suggest that a plane cannot take off without moving forward relative to the ground. The less clear answer is that, in just the right conditions, wind can be strong enough (and in the right direction, from front to back past the place) to provide the same amount of "lift" that a normal, non-stationary takeoff would provide. So if that were the entire story, the short answer would be "yep, if it's a really windy day, a plane could take off without moving". Fun fact, this is also true of literally everything -- please see recent Glen Powell/Daisy Edgar-Jones vehicle "Twisters" to see this happening to people and entire neighborhoods worth of things :) Just cause it ain't got wings doesn't mean it can't "take off"! The second level of understanding comes when you can no longer give the benefit of wind to the scenario. How the heck do you generate enough air movement to provide "lift" at that point? Well, that comes back to how the plane moves forward once the wheels are OFF the ground -- the propeller, or turbine. I mentioned these devices "throw air back" in order to provide thrust to move the plane forward. Well, shoot, there's some moving air right there, which is kinda like wind! But is it enough, and in the right place and direction, to generate "lift"? This is where the myth probably stops being conclusive in its answer, because the last question I asked depends entirely on the type and weight of plane. Let's start with an example where the answer is definitively "no": big aircraft like jetliners. For these planes, the device (turbine) sits UNDER the wing, and pulls air ONLY UNDER the wings -- which matters a lot. Lift is not generated based on just what the air UNDER the wing is doing, but the air ON TOP of the wing has to be moving quickly as well. Without both sides of the wing having air flowing over it, your wing won't generate nearly the intended amount of lift, and you won't get takeoff -- especially not with how heavy the planes are. The heavier the plane, the more "accidental lift" (lift that can be generated by the wings thanks solely to air coming from the air-moving device) you would need for an unintentional takeoff. Now for an example where the answer TENDS to be yes: small RC places. First the simple difference: they are much, much lighter, which means that if you have enough "accidental lift", you could more easily acheive takeoff. The second more complicated difference is that their propellers sit at the FRONT of the plane, and tend to sit at about the same HEIGHT as the wings. So, they are not only throwing air back across the wings (which is good for lift), but they're ALSO throwing air back on both the TOP and BOTTOM of the wing (which is also good). With those 2 differences, you get a lot of hobbyists saying they have successfully tied down their RC planes on a not-windy day and still managed takeoff. How easy it is to do that also factors into how fast your propeller can spin, but that's more of a side note. There's a wide spectrum in both of those variables (plane weight, and where air is thrown by the propeller/turbine) and I guess the Mythbusters COULD have dove into finding exactly where the line was on viability for self-induced takeoff, but (a) that would have taken a LONG time, and (b) at that point you're not really busting a myth because the answer is "it depends". Credentials: I majored in Mechanical Engineering, with a particularly strong interest in fluid mechanics and aerodynamics, and even spent a while designing a formula-style racecar's downforce-producing foils on my college's racing team involving a ton of fluid dynamic simulator software.
Aeronautical engineer here👋 I think you very clearly explain the origin of the controversy. The only problem is that there is no physical real life difference between version 1 and 2 of the controversy as you explained. An aircraft on a conveyor belt, regardless of the belts speed would start to move forward when applying thrust. The only way an aircraft would remain stationary would be when tied down or without engines. I don't think anyone is debating if an aircraft can take off in that configuration. thinking that a conveyor belt can keep an aircraft stationary means that you miss the relevant parts of an aircraft. Anyhow, I love these discussions. Mythbusters is a part of why I wanted to become an engineer in the first place, might be the same for you too. I think it is great that people who have grown up with mythbusters are now engineers/scientists themselves and can still discuss about this. Learning to think critically and analytical is the goal here, I hope anyone reading this is inspired enough to take part in the discussion. As you clearly explain, there are almost no wrong answers in science, only wrong assumptions.
I think the way to demonstrate the way a lot of us originally understood the myth would be to put a glider towed behind a truck on a treadmill. If the truck is driving exactly the speed of the moving treadmill, you could just as well hold the truck in position in space with its wheels freewheeling on the treadmill. The glider would not lift off in this case, unless the treadmill was rough enough to create enough airflow to provide lift, which is unlikely, even in a small scale model. This setup distills the idea of the myth better, but it does not correspond to the way most people talk about the myth, and the version tested here, because here the plane is using its engines.
I think of the "plane on a conveyor belt" question as a great example of how a poorly structured question can defeat any amount of logic or information. The problem never had anything to do with physics; the question itself was flawed enough that there was no correct answer (or multiple correct answers) so of course the argument could never be resolved. Moral of the story if you need one: When you're arguing with someone it's always worth pausing to make sure you both know exactly what you're actually arguing about; conflict rooted in misunderstanding will just never end.
I'm not stupid, as a rule (oh, I've done my share of stupid things...) I was in the camp, that thought, no moving air (air-speed), over the wings... no-lift... and of course, that is true BUT, after thinking about what 'actually' deceived me, knowing full-well, the wheels are-not propelling the plane, the propeller is... I think that visually, perhaps my limbic-mind, equated rolling-wheels, contacting ground, as the tractive-force - it's essentially, an optical illusion - I don't _SEE_ the propeller, pulling through the air, I just _'know'_ it is... How many times, have we known better, and done far less than that? How does this happen? It isn't necessarily, lazy, stupid, or ignorant, to what we're observing outwardly - the cave-dweller's instinctual responses are very-much, alive and well, in us - it's learning how to consciously, see passed that innate, visceral, response, that takes the work, time, and patience, to respond accordingly, rather than reacting, with the conviction of belief... perspectives and perceptions... My late grandfather once said to me... _"believe, none of what you hear, and only half, of what you see"_ Cheers-
Jamie was trying to explane how an airplane (or jet) moves forward and takes off because the engine power creates the needed speed and wind to create lift on the airfoil to raise the airplane into the air. The wheels are free wheeling. What ever surface, moving or not, has nothing to do with producing enough lift to get it airborne. That's why the myth is busted, and as Jamie said... it's stupid.
The thing that got me about the plane on a conveyor belt wasn’t the way in which a plane drives itself forward. It was whether or not the propellor alone could drive enough air under the wings to create lift. I’d always assumed the propellor created some amount of the air flow resulting in lift, but that its job was really to pull the plane forward so that all of the surrounding air flows over the wings to create lift. Said differently, I’d just assumed the air that the propellor could drive over the wings would only spread over a small portion of the planes wingspan, and that that surface area the air covers wouldn’t be large enough for the plane to get enough lift to take off.
The propeller on a plane works like a screw in the air, pushing it forward. It’s not like a car where the wheels are driving it. The plane’s wheels just spin freely, so even if you have a conveyor belt going in the opposite direction, it doesn’t matter. The thrust is coming from the propeller pushing against the air, not from the wheels. If the plane was actually powered by its wheels (which it’s NOT), then yeah, a fast enough conveyor could stop it. But since the thrust is from the propeller, as long as it’s pushing air, the plane moves forward, gains speed, and takes off. ✈ I’m a little surprised -it wasn’t that difficult to guess.
I think the controversy comes from how the question is posed. If you apply only enough thrust to overcome the drag of the conveyor belt and the plane does not move forward in space creating airflow over the wings, then no, it will not take off. That is how I imagined the myth when initially asked. What I want to know is if the DeLorean from Back To The Future would travel time if going 88 mph on a treadmill. 😉
The plane was moving forward. It still moved forward the 80ft req for take off. Wheel speed then would have been 50mph. 25 for the plane moving forward and 25 for the conveyor moving the other direction. Thrust, lift, drag, and weight are still real regardless of how fast the wheels spin. The myth is if the plane was stationary due to the wheels moving at same speed as take off speed. They clearly missed the mark on this one.
@@PublicAtLarge *NO!* He is supposed to repeat the transmission, followed by his Call Sign, so they can verify that the instruction was copied correctly by the right person.
I remember in middle school watching this for the first time and thinking, “How could the plane on a conveyor belt thing be even remotely controversial!? Did those who expect the plane to remain stationary have TBIs?” Now, I remember that nearly half the country think the world should burn so… yeah. There are some whose stupidity is beyond all comprehension.
Isnt the whole point of the plane myth is that it isnt actually moving foward? Using a long runway and cloth kinda defeat the whole purpose,, its just taking off normally ?
No, you appear to have misunderstood. The 'conveyor belt' moving backwards at the same speed the 'plane is moving forward does *NOT* mean the 'plane is stationary, or, as you put it _"... isnt actually moving forward"_ The speed of he conveyor belt does *NOT* matter; the 'planes wheels are freewheeling. It sounds more complicated, but "it's just taking off normally". Best Wishes. ☮
The conveyor only allowed build of thrust minus ground drag. Didn't help lift unless there was some prop created lift....should work under certain adjustments.
The funny thing with the poly foam yes it does get hot but not hot enough to light things on fire. When I sprayed it we tested it because we wanted to understand what was happening, we sprayed a wooden box made of soft pine and then took our thermal camera too it and the other side only got to 140 degrees, after 2 minutes it got down to 80 degrees. Then cut the box open and it was fine on the other side no charring or anything. We were worried because someone wanted 8 inches thick and it was hard to keep coming back to it but after our test that job went so quick.
Why? 140F (or even C) is nowhere close to the ignition point of conventional building materials. You need 490°C (914°F) before wood will ignite without an open flame to get it started. If you're worried about rubber, plastic, fiberglass, insulation foam already in the wall, etc... 140F is a reasonable temp for the sunny side of a house's interior wall space to reach. Car interiors get hotter than that.
@ because foam rigs go up in flames because of the hose just being hung up in the rig, it’s coming out of the sprayer at 130. Which is not that hot but it gets hotter as the chemicals mix we got a. Internal temperature of 260 in the middle of fresh sprayed foam. What we worried about is spraying 1000 square feet of wood that’s got dust and other debris like spiderwebs and things that can catch fire at low temps. But yeah to make it short the truck can go up in flames with the hose inside when the hose is only be heated up to 120 degrees. And when spraying in older homes fire risk goes up a lot more.
A conveyor belt only moves the wheels. What would need to happen is it needs to be in a wind tunnel that blows air proportional to the speed of air moved by the propeller. THEN the plane would stay stationary.
Which should be so obvious to the Mythbusters that it's not even worth testing. I don't know how dumb they think their viewers are. I know Adam and Jamie have pretended to not know what it takes to set off C4 for the purposes of a myth test.
@@reliantncc1864 *"I don't know how dumb they think their viewers are"* You' be surprised at he amount of discussion ensued by this topic at the time. A fairly large number of people actually thought that the airplane should not move.
@@reliantncc1864 its a show dude most if not all the myths can be busted or confirmed with science but than you're just getting a lecture nobody wants to watch that
My understanding is that only the air speed is matter, the speed of air flow against wings. The air flow speed between the top and bottom of the wing surface creates the different air pressure and in turn creates the upward force to lift the plane. A standing still airplane will take off if it is facing a big fan blowing air by 25 miles per hour. In the normal taking off situation, the ground speed (wheel speed) match air speed; if in the tail wind direction, the ground speed will be much more than 25 miles to take off; in head wind, may be 15 miles will take off.
The point of the myth here is that you are still getting wind across the wings. The plane doesn't drive the wheels, they spin freely. So even if you've got a conveyor belt traveling the opposite direction at the speed of sound, once the airplane gets its propeller going, the ground's speed doesn't matter. The propeller pulls the plane forwards. The only way to stop a plane from taking off this way is to actually prevent its *wings* from being able to move forwards, like with posts or something. Also, we can't just use conveyor belts to shorten runways for much the same reason. What the plane "cares" about is the speed of the air running over its wings, so unless we shorten the time required to get up to that speed, we won't shorten the distance required.
@danriehl4244 I understood the part about the wheels being free-spinning and the propeller creating the forward moment. What I'm not so clear on is how the air would move across the wings if the plane wasn't moving relative to the ground or the air around it. If I run on a treadmill, I don't get a breeze moving across me because I'm not moving relative to the air around me.
@@infamoushacker4chan883you aren’t moving forward on the treadmill because you’re pushing off the treadmill at the same speed the treadmill is moving. The plane moves because it’s pushing off the air not the treadmill, so as it pushes the air it moves forward on the treadmill, its wheels start at the same speed as the treadmill and accelerate faster than the treadmill as the plane gains speed from pushing off the air, increasing wind across the wings, until it takes off. Make sense now?
@infamoushacker4chan883 oh, I see what you're getting at now. The only thing that matters to become airborne is the speed of the air over the wing. Light aircraft need to be anchored when parked outside because strong winds will cause them to lift off. Even jet aircraft can start lifting off the ground in high enough winds. The Wright brothers referred to their Flyer as a kite, because it was essentially a giant box kite. The word airplane hadn't been invented at that point. And like any kite, if you have a strong breeze, all you have to do is hold it into the wind for it to take flight. If it's not very breezy, you'll have to run for it to catch enough air to take off. The propeller is just a tiny wing spun fast pulling the craft forward with air instead of traction on the ground. Helicopter blades are just giant props pointing up, eliminating fixed wings.
IMO, it all boils to is the power source able to generate enough air flow under the wings. think abt this, the power source (propeller/jet) job is to pull/push the plane forward so that the air flow speed is increased to the extent the lift is generated greater than the weight (thrust to weight ratio) Assumption: the conveyer speed matches the take off speed of the plane and no winds. so the only consideration (ignoring the precession) is if there is airflow under the wings. this would be dictated by where the propeller or engine is located a. In front, the propeller or jet pushes the air towards wings. more effect in case of propeller since air flow grows as funnel so it covers more wing area whereas jet airflow is more like a high speed stream concentrating only some cross section of the wing. This will create the required airflow to create lift. Once the wheels lose contact with belt, it is under its own power and will fly forward. b. If the engine is at back , does it pull in enough air to lift the wings? usually incoming air's speed while taking off is lower than the 'thrust', why else would planes need extra power. so the if the propeller/jet is at back not enough airflow is generated to lift wings at the set take off speed
Your analysis becomes faulty. You start well; _"...it all boils to is the power source able to generate enough air flow under the wings"._ lift is generated by airflow over the wing; when the lift is greater than the weight, the 'plane lifts from the ground. It doesn't matter significantly where the propellers are located as long as they can generate enough thrust to push the 'plane forward fast enough. 'Planes with propellers at the rear at called "pushers', and propellers at the front are 'pullers'. The Wright brothers first 'plane was a 'pusher'. The propellers were behind the wings. Successful 'planes are still being built and flown with propellers, or jets, at the back. So the analysis about pullers' vs 'pushers' reaches erroneous conclusions. Further, if you watched the video, you will see that both the model and full-size 'planes are 'pullers' with their propellers at the front, and they both can take off from solid ground powered purely by their propellers. You can find many examples of ''pusher' aircraft by searching the web. One of the 'planes which could take off from runways located at unusually high altitude (which is harder than at sea level) was a 'pusher' called the BA VC-10. Some of the experimental or prototype 'planes which are intended to use fuel much more efficiently are 'pushers'. The speed of the conveyor belt is irrelevant. The 'planes wheels are freewheeling, and contribute no thrust. Best Wishes. ☮
The airplane Sketch is just crazy the treadmill can't have any effect because the source of thrust is independent on the airplane … So treadmill or no treadmill the airplane will go forward no matter what…
The only thing the conveyor belt is moving is the wheels. These can be spun at very fast speed with hardly an power at all. As soon as the aircraft moves forwards, it comes off the conveyor then takes off in the same distance it always takes.
Equipment used for cleaning [radioactive] disasters get contaminated (picks up) the radioactive material. The bugs never come into contact with the radioactive material, only the radiation. Best Wishes. ☮
Its frustrating that they even had to test plane on a treadmill. Aircraft ground speed means nothing to flying, only air speed matters since that is what generates lift on a wing. A Cessna would do a vertical take off and landing in an 80kt wind (ground speed zero if flying into the wind, or would have a take off and landing ground speed in excess of 130kts if flying with an 80kt tail wind but either situation simulates the same physics since moving the air and stationary ground is equivalent to moving the ground beneath stationary air.
Most of the time, you just need to reflect the radiation back into the room. The fact that they handled the insects with no real protection means they weren't hit with particle radiation. So the source can be reflected like light. They probably would be fine to cross the line, but they might have a safety cutoff that detects someone heading into the room.
I have to say the plane on the conveyor belt confuses me. The lift doesn't come from the engine or the wheels, but the air flowing over the wings from moving forward. If the conveyor belt is moving in reverse at the exact same speed, it shouldn't matter that the engine is pulling the plane forward because the conveyor belt should be pulling the plane back at the same speed, so the plane should stay put. The plane wasn't taking off on a conveyor belt but getting enough traction on the solid ground beneath the conveyor belt tarp to allow it taxi down the conveyor belt, regardless of the belt moving under it. I keep hearing Jamie talking about the engine runs the propellor, but that should make no difference if the plane is truly trying to take off on solid ground that is moving with the wheels. I'd like to see this test again on a conveyor belt that is made of solid slats so that the plane can't get traction from the ground under it and see what happens.
the wheels spin freely unlike a driving car so pullinbg the tarp just causes them to spin faster but the motion of the air does not change and the plane uses the air to move. Imagine it was you with rollerblades on with a railing that was still you could use to pull yourself. the tarp could move but when you pull on the railing you still move forward even if the tarp is going the other way. The air is the railing for the plane. If you wanted the plane to stay still you would need a wind tunnel pushing air against the plane but even then it would still take off just not be able to move
The airplane "myth" is obvious! The only force retarding the craft is wheel-bearing friction, which is tiny, plus the treadmill will help the aircraft a bit by creating airflow under the wings, creating lift. If anything, a plane on a treadmill should take off earlier!
They do! I used one to launch a RC airplane that isn't able to take off under its own power when I was a kid (you were supposed to throw it with one hand and then remote with the other).
The RC club I’m in ran the plane on a conveyor belt experiment in November 1999. We were able to prove without a doubt that the propellor forcing air over the wings causing lift is what makes the plane take off. A plane tethered with 50 foot of fishing line staked to the ground and stretched out was able to take off and hover without ever moving forwards. It took 2 attempts with an experienced pilot to get it to hover at about 10 feet. On the 3rd attempt the fishing line was cut as the pilot applied power and it gently propelled forward as it rose into the air more. We actually took a photo with the club members standing under the plane while it was hovering. We also tried same experiment on a treadmill and the results were no different.
2 months later a jr member asked would the results be the same if the treadmill was ran in the opposite direction, so once again it was all set up and turns out as long as airspeed over the wing is correct the plane simply went straight into a hover at approximately 10 feet.
Correction: it's not the propeller forcing air over the wing that causes it to climb. The propeller pushes air back, resulting in a thrust force, which accelerates the aircraft. Acceleration leads to increase of airspeed, which gives lift. You are talking about 3D planes and hovering, which is in fact high-alpha operation. In that case, the propeller generates enough thrust to lift the airplane off the ground without airspeed. The experiment isn't about that.
The ground and wheel speed have nothing to do with the wings making lift ! When the wing has air moving past the wing above stalk speed, the plane will fly. Those wheels and ground will have no effect.
Remote Controlled Aeroplane Shenanigans? It’s called Plane On A Conveyor Belt, guys! If you’re gonna post the episode online, at least title it correctly
It wouldn't work I haven't seen the full video yet, but I'll say it right now that speed isn't a factor of obtaining lift It takes air moving around the airfoil in order to get lift If you just run a plane on a conveyor belt, it can't achieve lift because no air is going around the wing The model plane didn't get lift, its engine just allowed it to move faster than the treadmill
If you had a conveyor belt that could speed up to whatever speed required, could you theoretically have a plane vertically take off from the conveyor belt?
The problem here is that the question is under defined. Interpretation 1: The conveyor belt moves at a speed v (relative to the ground) backward equal to the forward speed of the plane relative to the ground. No problem plane takes off. The wheels just spin twice as fast as they would otherwise. Interpretation 2: The conveyor belt moves backward at a speed equal to the velocity of the plane relative to the conveyor belt. But if you work out the math that means that the plane must be standing still relative to the ground ... in other words you keep speeding up the conveyor belt until you bring the plane to a stop relative to the ground. As long as the wheels of the plane aren't completely frictionless this is always possible and the plane obviously can't take off.
Yeah I kind of assumed they were going to keep matching the planes speed on the belt, but I guess that would be hard to do. Kind of a trick question type of thing..
@ Yea, though TBF it is matching the plane's speed relative to the ground so it's not delibrately a trick question just one with two reasonable interpretations.
The problem with theory 2 is that spinning wheels that fast would cause a wheel failure long before you stop an airplane from taking off. The thrust being produced is independent of the wheels, it’s like your car being in neutral on a conveyor belt. The wheels will spin just as fast as the conveyor belt is but if you but a jet engine or propeller on top of your car then you will move forward. So yes it is TECHNICALLY possible, but not what would happen in the real world.
@ Depends on how much friction is being produced by the wheels when they spin. Especially for a small plane those wheels aren't made to minimize frictional losses so while you would no doubt eventually get a failure due to heat buildup it certainly wouldn't happen immediately. There would be some non-zero period of time where it prevented take off. But this is all a bit besides the point because it's a thought experiment. I'm perfectly happy saying that if you idealize friction to be zero in interpretation 2 you can't satisfy those conditions but that's just not the same thing as saying the plane can take off if those conditions are met.
The airplane accelerates to take-off speed, relative to the ground, and takes off. The wheels are 'freewheeling'. It really doesn't matter what speed the conveyor belt is moving. A solution to "Interpretation 2" is to move the conveyor belt *_in the same direction_* as the 'plane is moving, *_maintaining the relative velocity between 'plane and conveyor belt at 0_* That fully satisfies the requirement _"The conveyor belt moves... at a speed equal to the velocity of the plane relative to the conveyor belt"_ _"If you work out the maths"_ that is a valid solution. Clearly, the 'plane does *NOT* need to be standing still relative to the ground. Best Wishes. ☮
How a pilot could believe he wouldn't be able to take off really surprised me. The myth itself seemed pretty dumb to begin with. The plane is disassociated with the ground. It's speed relative to the air around it is really the only factor. The drag a conveyor belt would impart to the planes wheels would be neglagable. You have to have no understanding of what is going on to think it would change anything and at that point, you know so little that even arguing strongly with someone about is dumb since you don't understand what is even happening
Notice how he says "if there's no air over the wings". The scenario in his mind is one where the conveyor has caused enough drag via the wheels to cancel out the thrust and make his speed relative to the surrounding air 0. That's not the myth. The myth is that a conveyor which is itself moving backwards at takeoff speed would be able to prevent the plane from achieving flight, which clearly isn't possible because the drag from the wheels is nowhere near as strong as the engine thrust.
@@nathanromero3430 I really hope that's the case. I can't see a professional pilot not understanding how his plane works so your probably right. Just to add some tension or drama for tv
The thing nobody ever talks about with the plane myth is that the WHEELS on the plane will be spinning twice as fast when it takes off - the speed the plane is moving forward PLUS the speed the conveyor belt is moving backwards. Maybe that will help people understand it more, because it’s not like the conveyor belt has no effect. The effect is just on the wheels only, not on the plane itself. You’d be able to drive forward with a car on a conveyor belt as well, IF you move the car wheels faster than the conveyor belt.
In a car you’d need drive the wheels twice the speed of the treadmill to continue forward at the same pace. The engine of the car drives the wheels. In a plane, the propeller pulls the whole craft, so the wheels will spin at whatever speed they need to spin, as long as they touch the ground. The ground is (virtually) irrelevant to how the plane moves through the air
@@Rad_Dan I don't know if you're trying to refute something that I said, but if you are, I think you're missing my point. I understand this myth, why people think the plane can't take off, and why they are wrong. I'm also aware of the difference between "driving wheels" (like on a car, connected to an engine) and "free floating" wheels (like on a plane), which just spin when touching the ground. What I was trying to add to the conversation is that the people who don't understand that the plane can take off seem to think something along the lines of "but that can't be true, because the conveyor belt must have some effect". My point is that the effect is on the WHEELS of the plane, which has no effect on whether the plane can fly, but most people discussing this myth don't seem to point that out. So my thought is that perhaps people would find this easier to understand if they note that the wheels on the plane, on the conveyor belt, would be spinning at twice the normal speed, so the conveyor belt has an effect (on the wheels) but that doesn't affect the forward speed of the plane. Hope that clarifies my point.
@@johnmaher5887 I get what you’re saying, I didn’t at first but with your follow-up comment I can tell that you were just trying to explain why the wheels would spin twice as fast to someone who maybe didn’t understand why, then complained that the “treadmill didn’t match the speed” or something like that. I had a bit to drink last night, and should’ve stayed off of UA-cam’s comment section lol, I hope you have a good one my friend
I understand why, but I'm still not convinced with the plane take-off. It still has forward movement. If it 100% stayed stationary, then took off, I'd be convinced.
you're missing the entire point. The reason the myth doesn't work is because pulling the tarp back doesn't keep the plane stationary it just speeds up the wheels
I will never not be grateful for these getting uploaded, hell yeah science time!
lol why not just say you'll always be grateful?
@@Jamie_D i will always sometimes maybe defiantly never not be grateful for mytbusters
@@muffinbra😂
@@zacharyclownphobic2316 I will probably maybe never not forget your smiliey face comment, this is the best thing that has ever happened to me in my entire life and i will named my first born child after you if a women ever lets me near her front butt
I believe Grant would have wanted this for everyone!!
Mythbusters in their prime. It was always a treat to see what they would test every week. So glad these are here.
The golden age of Mythbuster. Missing Grant Imahara, he left us too soon.
I had no idea.
God rest his soul, so sad he's gone already
I find myself thinking about him quite often for some reason. I loved this show and this crew.
@@bebophippie1781 and did stint at unofficial star-trek, TOS, the play Solu the pilot too until it was closed down; competing to must with GG star-trek with wasn't that hard, the end of the test card signel screen was doing better GG star trek at the time.
I met the three mythterns once at a convention more than ten years ago
I still miss that show
mythbusters is such a comfort show to me, my saturday and sunday mornings have gotten that much better!
Thanks so much for uploading these to UA-cam!
I finally understand it, the wheels of the plane are just spinning twice as fast. the plane is still going to pull forward no mater how fast the wheels are already spinning on a treadmill. It'll work every time unless a wheel fails or something. The force of the propeller won't allow the plan to just set there. Its pulling on the air, not just the ground.
Wow, it finally makes sense now. I remember watching this on TV when it aired and I wasn't satisfied with the experiment because I thought they didn't match the speeds.
Interestingly, you could actually argue that they _didn't_ match speeds. The question is poorly defined, leading to multiple possible interpretations of what "matching speeds" means, and in one of them, it's actually physically impossible to do if the plane is moving. (If you're curious about the details, xkcd has a page on it.)
By that interpretation, _Mythbusters_ should've tested this by bolting chocks to the runway so the plane's wheels couldn't move forward or back.
Also, I made the same logic error you did. Nice to know I'm not alone. 😊
Let me try to understand this. If there were no rolling resistance in the wheels, the plane would stay in-place on the moving treadmill (stationary to the surrounding terrain) while the planes engine is completely powered down. You can test this by placing a Hot Wheels car on a sheet of paper, and pulling the paper backwards. It is the same as the trick where you whip away a tablecloth and all the plates stay in place. Like the tablecloth and plates, the rolling resistance of the wheels is very low once the initial friction is overcome. Up to this point, all the energy spinning the planes wheels comes from the treadmill. For a plane to achieve lift, it's all about airspeed, so it's irrelevant if the wheels are spinning. In fact, a plane can lift off from stationary without an engine if there is enough headwind. On the treadmill, the rolling in-place plane has zero airspeed. Once you add energy in the form of the engine turning the propeller, this balance will be overcome, and the plane will gain airspeed at the usual rate.
It’s not that the wheels spin twice as fast lol. It’s because on ground, in a car, your engine drives the wheels. In a plane, the propeller pulls the entire craft forward, the wheels are going to spin on the ground (as long as the ground touches the wheels) as fast as they need to because the propeller is pulling the whole craft. They put a toy car on a treadmill and push it, that’s a good way to picture what forces are in play
They clocked the plane's takeoff speed as 25mph prior to taking off on the conveyor belt, which they set for 25mph in the opposite direction. They should have put a speedometer on the wheels, as that should have indicated takeoff would have happened at 50mph wheel rotation speed which I think is the point they were trying to make! They didn't say if the plane took off at 25mph as recorded on the pitot tube (airspeed) and what distance it took off at relative to the non-conveyor belt distance. It's a bit frustrating that they didn't conclude with the math which should have revealed a lot. I suspect the conveyor belt itself had some minor effect on the direction and speed of the air, but that's what determines if a plane takes off or not-- the airspeed, not the groundspeed. If you chocked the plane from rolling back and blasted air at the plane from the front at takeoff speed, it should lift off from the ground from that static position, even with the engine turned off.
yes, very good. and I am REALLY surprised the pilot did not know better since for flying there is literally airspeed and groundspeed, and its the airspeed that all flying is done by. this takes a role in every start and landing, for example with wind...
Thank you for uploading this and all other episodes. Hopefully these entertain and teach people for centuries... or at least some decades more. Regarding the plane myth, I think the controversy will always be born from focusing more on the setup that the physics facts:
A plane flies because (as the lift formula tells you) it's got a wing designed to create lift higher than its weight at X speed. The problem with the setup of the myth is that it never specifies whether the plane should match the speed of the conveyor, because otherwise it'd be stupid simple: if the plane is supposed to remain stationary like the car did, it'll never take off, no matter the speeds involved so long as the net is zero.
If the plane is allowed to develop its own speed taking the net above zero, it just needs to go fast enough to generate lift, and it'll always take off if it reaches that speed.
It's a stupidly simple thought experiment, that only becomes complex and confusing when you try to put it in practice.
I'm so glad these are uploaded, reliving my childhood.
The plane on the conveyer belt works because the wheels are free moving and not providing any sort of drag. The plane takes off because the propeller provides the thrust and moves the plane using the air as its medium. The wheels are still just free moving, unlike a car. Now a plane flying against fan blowing against it, that's different.
We know. Adam said this very thing multiple times.
The wheels have nothing to do with it. Autistic.
@@SophiaAphrodite Yeah but I am seeing in the comments people are still questioning the myth.
Yeah, but there is downward force from weight as well as friction from the tires. This myth's conclusion assumes none of that exists, which makes the whole thing silly nonsense, because that's the part that interacts with the conveyor, which is what the whole thing is about....
@@Cuzzzo42 There is, but it's nowhere near enough to offset the thrust of the engine or the lift from the wings. Planes ultimately don't weigh very much for their size, or they wouldn't fly at all. You're basically never going to, in real life, be able to create enough drag to prevent some amount of forward motion relative to the air and therefore lift, since the wheels have no resistance of their own from a driveshaft or anything.
The lift also starts removing the weight on the wheels and therefore the drag they cause, so it quickly becomes a feedback loop where the plane will take off. In the purely hypothetical situation where the conveyor is actually capable of producing the drag necessary to keep the plane stationary relative to the air, then it wouldn't take off. It's just not feasible to create that situation with a belt in particular.
Wheel speed is irrelevant to the plane taking flight. The propeller (or jet engine) makes it move so the plane still takes off.
The easiest way to understand the airplane on a conveyor problem and why the plane will always take off is this:
Attach a rope to a wall and put a treadmill in front of it. Put roller blades or skates on your feet and stand on the treadmill. It does not matter how fast the treadmill moves, you will always be able to pull yourself forward with the rope.
The rope represents the thrust of the engines of the airplane. It doesn't matter what the wheels on your roller blades are doing, you can still pull yourself forward. The wheels on your roller blades AND the wheels on an airplane are free wheeling. They aren't attached to a motor or anything, so as the treadmill changes speed, it will change the wheel speed, of course, but it has no effect whatsoever on the airplane's forward movement, which is wholly provided by the engines.
Meanwhile, that ultralight pilot is in the unique position of having done something nobody in the history of the world had ever done.
You don't need a conveyor belt.
Around 1984, our airplane (N51305) was on tie downs at the Mojave Airport. My biological father got a call from the tower. Our airplane was hovering in the wind trying to take off. No propeller running, no forward motion of the airplane. Just good ol' fashion wind.
Bush pilots do this all the time to land and take off with no space.
That's a different situation from the myth though. The myth is about the ground moving in opposition to the plane, not the air. The plane would take off in both cases, but they're still fundamentally different situations. So it wouldn't be a valid way to test this particular myth.
@@MichaelDavis-zu2ko It kind of does relate, if you look at it from a 90 degree angle.
Single engine STOL aircraft prove this to be a non-issue. What gets the plane in the air is air moving over the wing, not the plane moving across the ground. As long as the wheel bearings reduce the friction of rolling the wheel across the ground to a point that just the prop can get it up to take-off speed, it takes off.
If you manage to get the conveyor moving fast enough to overcome the wheel bearings, the plane can't get up to take-off speed. (That and the tires would probably melt...)
@ I never said that it’s the plane moving over the ground that gives it lift. That’s obviously not true. I’m just saying that, for the sake of the experiment, it’s not the same to test lifting off while stationary to the ground with wind vs testing taking off while the ground is moving but not the air. The myth specifically calls for the ground to be moving backwards, that’s the whole premise of the myth. If you don’t test that, then you didn’t test the myth.
@@MichaelDavis-zu2ko You stopped reading... Already answered.
The biggest surprise in this episode is the surprised pilot. If you hold a pilot license, you should know something about thrust, drag, airfoil, and generally the physics behind keeping an airplane in the air. But apparently not.
I suspect he said what he did just to heighten the "suspense." If he really thought he would not get airborne, then he really was clueless how planes work.
To be fair, he's an ultralight pilot, which generally has laxer licensing requirements. My father used to fly ultralights legally without any license, but given that was thirty years ago and in New Jersey, I don't want to say the pilot might not be licensed at all more then a decade later and in California, but he might well not have a full single-engine certification.
@@tildessmoo Despite them calling it an "ultralight", the pilot said it weighed 400 lbs (146 lbs heavier than the FAR Part 103 limit), the tower called it a Light Sport (a FAA-certified category of aircraft requiring a license to operate), and there was an N-number registration on the aircraft (only required on certified aircraft, not ultralights).
Ask any A&P mechanic, many pilots are not the sharpest tacks, lol
Yeah but how would any pilot really know this until it was tested. There would be no precedent to go off of. Anything that they would've "known" about this phenomenon would have been theoretical anyways wouldn't it?
If you think they did the plane on a conveyor belt experiment wrong, read this comment (or actually watch the video, around 21:45).
The reason "can a plane on a conveyor belt take off" is so controversial is because it's a poorly formulated question. It contains an implicit assumption for most laypeople - that the plane is not moving relative to its environment - but that assumption is inaccurate.
If the question was asking, "Can a plane take off while stationary relative to the air around it?" the answer is obviously no. But that's not the question being asked. The myth is that the plane can take off on a treadmill and because a plane's wheels spin freely and it's the propeller that moves the plane forward, the plane can move forward no matter how fast the treadmill is moving in the opposite direction, and therefore it can take off.
Yep. There's a hypothetical situation where the conveyor could be moving fast enough to create a drag/friction vector opposing the thrust vector large enough to cancel it out, but the belt would be needing to move at basically supersonic speeds. It's not realistically feasible, and it's certainly not when the belt is moving at takeoff speeds. And such a conveyor would likely move the air above it, providing some headwind and lift all by itself.
For me, it was always simple. The plane does not derive locomotion from it's wheels but it's propeller screwing it's way through a fluid - in this case, air. The wheels are simply a method to reduce the friction.
It would have been great to measure the speed of a wheel to show that it's spinning twice as fast as the plane is accelerating!
@@zimeron1 For the sake of that hypothetical, the belt would destroy itself from friction at those speeds.
Veritasium made a similar video called "Risking My Life To Settle A Physics Debate". The premise is slightly different, but this question makes me think about it.
Xyla Foxlin also made a video too called "Building the Vehicle Physicists Called Impossible (feat. Veritasium)"
내 어린시절을 다시 떠올리게 해주셔서 감사합니다. Adam과 Jamie는 내 영웅이에요.
Yes
Probably one of my favorite episodes. I been flying rc planes since I was 4yrs old and I’m now 21 flying big turbine jets that cost more than a car.
“Remember, they were bred to die for science”
I think the controversy in the airplane on the conveyor belt myth is all due to the two interpretations:
1, as seen here - the conveyor belt moves backwards at a fixed speed equal to the takeoff speed of the plane.
Result - airplane takes off normally, but its wheels spin two times faster than normal.
2 - the conveyor belt can speed up to an unlimited speed to keep the airplane in the same place with respect to the air.
Assumptions: wheels have perfect traction and can spin at infinite speed, conveyor generates no airflow on its own.
Result - plane remains stationary generating its full thrust, but most likely doesn't fly, as the airflow from its propeller or other engine is not normally directed over the wings, and its wings do not move with respect to the ambient air. There can be exceptions, as some airplanes do have overpowered engines mounted right above the wings, intentionally to shorten the takeoff path (like the Custer Channel Wing). They are not intentionally generating additional backwards thrust away away from the wings to avoid moving forwards, but if they did they would take off vertically in a rather uneconomical way (would be a lot easier to just blow the air down like a normal VTOL).
Yes! When I first heard the premise, my mind pictured interpretation #2. Plane stationary, no flight. It seemed so obvious that I was about to pause to try to figure out the catch. Then I saw the propeller, and I was like... oh...well yea, of course it'll fly. The wheels spin freely. They're irrelevant and so is the conveyor belt.
This reminds me of one of those ambiguous riddles that technically has more than one answer because the question was poorly worded. I suspect they knew this too, but felt like it was worth filming just for fun. Or to troll us.
Idk, interpretation issues kind of annoy me. I also zoned out a bit with the bug stuff. Not completely terrible, but not one of my favorite episodes. I think I'd actually prefer the Pirate Adam one 😬
I don't understand your 2nd interpretation, what exactly were you expecting them to do instead of what they did?
Might be misunderstanding, but for the 2nd scenario, we already know the wheels are a red herring, so just chain the plane to the ground and see if it takes off.... surely there's no contention over how that turns out
@@litarea 2nd interpretation is exactly what I imagined they were testing for. Flatten the plane and the conveyor belt to a 2D X-Y graph with the plane sitting on the x axis and the y axis being the front of the conveyor belt, if the plane is required to maintain it's position on the x axis while the treadmill is on, will the plane be able to take off?
If the belt could just keep spinning faster and faster it would probably pull in enough air to push the plane up :)
Which would of course then come down very fast after moving away from that air current.
Myth busters (show that I've been watching for years) + my hobby!?!? It's a miracle🙏😂😂😊
I feel so bad for Jamie. You could tell from the beginning that he was frustrated about having to do this myth by the way he acts and talks. He rarely ever expresses sarcasm but did so when the RC plane left the treadmill, and he was easily irked when he couldn't keep it on the paper conveyer belt. Good for him for sticking with it and doing the episode though; hopefully it finally silenced all those silly doubters!
Unfortunately, I don’t think it will silence doubters. :)
The fact that plane moved forward along the treadmill tells us that speed of treadmill is not the same as speed of the plane, what is the main requirement of the myth.
It's so damn simple: no airflow, no lift, no flight, no matter how fast the treadmill is.
Good thing the treadmill doesn’t impact airflow!
The aircraft moves due to thrust from the power plant. In a car, the tires produce the forward thrust for the vehicle. In the plane, the tires are simply there to roll. Thus, thrust is still produced and the aircraft still moves forward, and still gets airflow over the wings, and still takes off.
@@aao_fox9387 This is correct, and so many people get it wrong. The plane will always fly because the FUSELAGE is what is being pulled through the air by the power plant, regardless if it is a piston engine or a jet engine. The wheels will just spin and spin against the conveyor, but the plane will move forward.
The problem comes from the misunderstanding about how an airplane does its takeoff roll. It has nothing to do with the wheels providing anything other than a platform for the airplane to roll on.
Ah yes. The GWS Pico FD. Long ago out of production. I still have mine. Great little airplane at the front lines of the foamy revolution.
It’s absolutely insane to me that this originally aired in 06…. 2006! I was 5 years old lol… you guys have been legends for so long now, I can only wish to even be half as cool as yall one day
Thank you
Airspeed ≠ groundspeed
truw but thats's not even the reason for this it';s just the simple fact that the wheels spin twice as fast and the plane more or less doesn't even notice
@@ghostrunner2138 Which is what people dont understand from this being even considered a myth. People even to this day say that even Jet engined planes wouldnt be able to take off, as if the speed the wheels spin has any impact on the forward momentum of the plane.
I love these show reruns….👀
But it makes me sad when I see Grant …😢
He was such a talented, cool guy …🙏🏻🙏🏻🙏🏻👍🏻
I think about that too
Finally a new episode
The only thing that surprised me, was that the pilot with "Ten years of flying experience" believed the myth
I love Mythbusters. Thanks for showing people that "treadmill airplane" is just stupid. No airspeed means no lift means that you just sit with the engines running... What are the wings for? Airspeed equals lift... Hello? J. (pilot from Michigan)
Chat... I don't think he watched the full episode.
20:40 I thought this video was very interesting and educational. I learned a lot from it.
Rest in Peace Grant Imahara. He was the reason why i got interested in Robotics and majored in Mechanical and Electrical Engineering
The way Kari’s hair length and color kept flipping back and forth … 😅
The plane was still moving forward. The idea was for the plane to stay put with the Throttle Maxed Out.
This is essentially just the equivalent of Taking Off With The Wind. You just have to go a little faster than usual to compensate. But it’s not Ideal, not to mention Highly Inefficient.
It doesn’t matter how fast the Propellers are Spinning. Air needs to be hitting the Wings at a certain Speed at the right Angle Of Attack in order to Generate Lyft.
For anyone looking for a summary of the "controversy" around the airplane myth, I'll provide my current understanding of the big picture. Unfortunately, this episode didn't help because it added ambiguity to the exact conditions being tested.
IF the myth was exactly what was tested on the show -- a free-wheeling airplane can or cannot take off on a conveyor belt -- there would be no contention. There is a fairly universal understanding that planes don't move forward on a runway thanks to an engine powering their WHEELS, but rather some air-moving device (propeller, turbine) throwing air back in order to move the body of the plane forward. Same thing is a lot more obvious on seaplanes, which have skids instead of wheels.
The DEBATED version of the myth is: if an airplane CANNOT MOVE FORWARD RELATIVE TO THE GROUND, can it still take off? There are 2 commonly-held levels of understanding that determine which side of the debate you fall on.
The first understanding is limited to the fact that planes take off (and stay up, thankfully) thanks to a force called "lift" that is generated when air moves past the wings at a high speed. The question then becomes, how do you GET air moving past the wings? The clear answer is to move forward, which would suggest that a plane cannot take off without moving forward relative to the ground. The less clear answer is that, in just the right conditions, wind can be strong enough (and in the right direction, from front to back past the place) to provide the same amount of "lift" that a normal, non-stationary takeoff would provide. So if that were the entire story, the short answer would be "yep, if it's a really windy day, a plane could take off without moving". Fun fact, this is also true of literally everything -- please see recent Glen Powell/Daisy Edgar-Jones vehicle "Twisters" to see this happening to people and entire neighborhoods worth of things :) Just cause it ain't got wings doesn't mean it can't "take off"!
The second level of understanding comes when you can no longer give the benefit of wind to the scenario. How the heck do you generate enough air movement to provide "lift" at that point? Well, that comes back to how the plane moves forward once the wheels are OFF the ground -- the propeller, or turbine. I mentioned these devices "throw air back" in order to provide thrust to move the plane forward. Well, shoot, there's some moving air right there, which is kinda like wind! But is it enough, and in the right place and direction, to generate "lift"? This is where the myth probably stops being conclusive in its answer, because the last question I asked depends entirely on the type and weight of plane.
Let's start with an example where the answer is definitively "no": big aircraft like jetliners. For these planes, the device (turbine) sits UNDER the wing, and pulls air ONLY UNDER the wings -- which matters a lot. Lift is not generated based on just what the air UNDER the wing is doing, but the air ON TOP of the wing has to be moving quickly as well. Without both sides of the wing having air flowing over it, your wing won't generate nearly the intended amount of lift, and you won't get takeoff -- especially not with how heavy the planes are. The heavier the plane, the more "accidental lift" (lift that can be generated by the wings thanks solely to air coming from the air-moving device) you would need for an unintentional takeoff.
Now for an example where the answer TENDS to be yes: small RC places. First the simple difference: they are much, much lighter, which means that if you have enough "accidental lift", you could more easily acheive takeoff. The second more complicated difference is that their propellers sit at the FRONT of the plane, and tend to sit at about the same HEIGHT as the wings. So, they are not only throwing air back across the wings (which is good for lift), but they're ALSO throwing air back on both the TOP and BOTTOM of the wing (which is also good). With those 2 differences, you get a lot of hobbyists saying they have successfully tied down their RC planes on a not-windy day and still managed takeoff. How easy it is to do that also factors into how fast your propeller can spin, but that's more of a side note.
There's a wide spectrum in both of those variables (plane weight, and where air is thrown by the propeller/turbine) and I guess the Mythbusters COULD have dove into finding exactly where the line was on viability for self-induced takeoff, but (a) that would have taken a LONG time, and (b) at that point you're not really busting a myth because the answer is "it depends".
Credentials: I majored in Mechanical Engineering, with a particularly strong interest in fluid mechanics and aerodynamics, and even spent a while designing a formula-style racecar's downforce-producing foils on my college's racing team involving a ton of fluid dynamic simulator software.
Aeronautical engineer here👋
I think you very clearly explain the origin of the controversy. The only problem is that there is no physical real life difference between version 1 and 2 of the controversy as you explained. An aircraft on a conveyor belt, regardless of the belts speed would start to move forward when applying thrust.
The only way an aircraft would remain stationary would be when tied down or without engines. I don't think anyone is debating if an aircraft can take off in that configuration.
thinking that a conveyor belt can keep an aircraft stationary means that you miss the relevant parts of an aircraft.
Anyhow, I love these discussions. Mythbusters is a part of why I wanted to become an engineer in the first place, might be the same for you too. I think it is great that people who have grown up with mythbusters are now engineers/scientists themselves and can still discuss about this. Learning to think critically and analytical is the goal here, I hope anyone reading this is inspired enough to take part in the discussion. As you clearly explain, there are almost no wrong answers in science, only wrong assumptions.
I think the way to demonstrate the way a lot of us originally understood the myth would be to put a glider towed behind a truck on a treadmill. If the truck is driving exactly the speed of the moving treadmill, you could just as well hold the truck in position in space with its wheels freewheeling on the treadmill. The glider would not lift off in this case, unless the treadmill was rough enough to create enough airflow to provide lift, which is unlikely, even in a small scale model. This setup distills the idea of the myth better, but it does not correspond to the way most people talk about the myth, and the version tested here, because here the plane is using its engines.
I think of the "plane on a conveyor belt" question as a great example of how a poorly structured question can defeat any amount of logic or information. The problem never had anything to do with physics; the question itself was flawed enough that there was no correct answer (or multiple correct answers) so of course the argument could never be resolved. Moral of the story if you need one: When you're arguing with someone it's always worth pausing to make sure you both know exactly what you're actually arguing about; conflict rooted in misunderstanding will just never end.
I'm not stupid, as a rule (oh, I've done my share of stupid things...) I was in the camp, that thought, no moving air (air-speed), over the wings... no-lift... and of course, that is true BUT, after thinking about what 'actually' deceived me, knowing full-well, the wheels are-not propelling the plane, the propeller is... I think that visually, perhaps my limbic-mind, equated rolling-wheels, contacting ground, as the tractive-force - it's essentially, an optical illusion - I don't _SEE_ the propeller, pulling through the air, I just _'know'_ it is... How many times, have we known better, and done far less than that? How does this happen? It isn't necessarily, lazy, stupid, or ignorant, to what we're observing outwardly - the cave-dweller's instinctual responses are very-much, alive and well, in us - it's learning how to consciously, see passed that innate, visceral, response, that takes the work, time, and patience, to respond accordingly, rather than reacting, with the conviction of belief... perspectives and perceptions...
My late grandfather once said to me... _"believe, none of what you hear, and only half, of what you see"_ Cheers-
Jamie was trying to explane how an airplane (or jet) moves forward and takes off because the engine power creates the needed speed and wind to create lift on the airfoil to raise the airplane into the air. The wheels are free wheeling. What ever surface, moving or not, has nothing to do with producing enough lift to get it airborne. That's why the myth is busted, and as Jamie said... it's stupid.
24:50
Pretty wicked seeing how the radiation emission interacts with the camera sensor, especially at 25:00 with the tons of white dots.
1:40 any 1st year Physics/Mech/Aero College student or RC pilot knows this answer... they musta felt ridiculous even testing this...
42:44 Grant’s expression 😂
This airplane myth literally took over the official forum.
20:18 LMAO
The thing that got me about the plane on a conveyor belt wasn’t the way in which a plane drives itself forward. It was whether or not the propellor alone could drive enough air under the wings to create lift. I’d always assumed the propellor created some amount of the air flow resulting in lift, but that its job was really to pull the plane forward so that all of the surrounding air flows over the wings to create lift.
Said differently, I’d just assumed the air that the propellor could drive over the wings would only spread over a small portion of the planes wingspan, and that that surface area the air covers wouldn’t be large enough for the plane to get enough lift to take off.
All you have to know is that planes with rear mounted propellers are a thing for your misunderstanding to be rectified. :P
@@kishinasura7701 I don't thing that changes anything about what I said, but thank you for the input :P
Shenanigans is now my favorite word
4:50 A segway with spinners is next level.
That tarp was a hazardous for the pilot. I was worried it might rip and snag a wheel or something else.
The propeller on a plane works like a screw in the air, pushing it forward. It’s not like a car where the wheels are driving it. The plane’s wheels just spin freely, so even if you have a conveyor belt going in the opposite direction, it doesn’t matter. The thrust is coming from the propeller pushing against the air, not from the wheels.
If the plane was actually powered by its wheels (which it’s NOT), then yeah, a fast enough conveyor could stop it. But since the thrust is from the propeller, as long as it’s pushing air, the plane moves forward, gains speed, and takes off. ✈
I’m a little surprised -it wasn’t that difficult to guess.
Ya RC stands for radio control not remote control! A remote is what you use to turn your TV on and off!!!
This is the best
Good stuff
Even though I myself have worked on insects in the lab, I feel bad for these critters. 😢
I think the controversy comes from how the question is posed. If you apply only enough thrust to overcome the drag of the conveyor belt and the plane does not move forward in space creating airflow over the wings, then no, it will not take off. That is how I imagined the myth when initially asked. What I want to know is if the DeLorean from Back To The Future would travel time if going 88 mph on a treadmill. 😉
The plane was moving forward. It still moved forward the 80ft req for take off. Wheel speed then would have been 50mph. 25 for the plane moving forward and 25 for the conveyor moving the other direction. Thrust, lift, drag, and weight are still real regardless of how fast the wheels spin. The myth is if the plane was stationary due to the wheels moving at same speed as take off speed. They clearly missed the mark on this one.
I love science.
45:35
“COPY THAT”!?!?!?
What Kind Of “Pilot” Is He!?!?!?!?!?
Though the usual thing they use is "Roger that", the word "copy" is similar in that it means you've heard the instruction.
@@PublicAtLarge *NO!*
He is supposed to repeat the transmission, followed by his Call Sign, so they can verify that the instruction was copied correctly by the right person.
I remember in middle school watching this for the first time and thinking, “How could the plane on a conveyor belt thing be even remotely controversial!? Did those who expect the plane to remain stationary have TBIs?” Now, I remember that nearly half the country think the world should burn so… yeah. There are some whose stupidity is beyond all comprehension.
my elected city councilman literally went on a tirade about how he's afraid of cell towers and "those ppl" want to make driving illegal". Yeah.
*"...nearly half the country..."*
That would explain the... oh wait, no politics here.
Isnt the whole point of the plane myth is that it isnt actually moving foward? Using a long runway and cloth kinda defeat the whole purpose,, its just taking off normally ?
No, you appear to have misunderstood. The 'conveyor belt' moving backwards at the same speed the 'plane is moving forward does *NOT* mean the 'plane is stationary, or, as you put it _"... isnt actually moving forward"_ The speed of he conveyor belt does *NOT* matter; the 'planes wheels are freewheeling. It sounds more complicated, but "it's just taking off normally".
Best Wishes. ☮
The conveyor only allowed build of thrust minus ground drag. Didn't help lift unless there was some prop created lift....should work under certain adjustments.
The fact that the conveyor belt idea even had to be considered mystifies me. Since the wheels don't actually drive the plane it will simply take off.
The funny thing with the poly foam yes it does get hot but not hot enough to light things on fire. When I sprayed it we tested it because we wanted to understand what was happening, we sprayed a wooden box made of soft pine and then took our thermal camera too it and the other side only got to 140 degrees, after 2 minutes it got down to 80 degrees. Then cut the box open and it was fine on the other side no charring or anything. We were worried because someone wanted 8 inches thick and it was hard to keep coming back to it but after our test that job went so quick.
Why? 140F (or even C) is nowhere close to the ignition point of conventional building materials. You need 490°C (914°F) before wood will ignite without an open flame to get it started. If you're worried about rubber, plastic, fiberglass, insulation foam already in the wall, etc... 140F is a reasonable temp for the sunny side of a house's interior wall space to reach. Car interiors get hotter than that.
@ because foam rigs go up in flames because of the hose just being hung up in the rig, it’s coming out of the sprayer at 130. Which is not that hot but it gets hotter as the chemicals mix we got a. Internal temperature of 260 in the middle of fresh sprayed foam. What we worried about is spraying 1000 square feet of wood that’s got dust and other debris like spiderwebs and things that can catch fire at low temps.
But yeah to make it short the truck can go up in flames with the hose inside when the hose is only be heated up to 120 degrees. And when spraying in older homes fire risk goes up a lot more.
A conveyor belt only moves the wheels. What would need to happen is it needs to be in a wind tunnel that blows air proportional to the speed of air moved by the propeller. THEN the plane would stay stationary.
Which should be so obvious to the Mythbusters that it's not even worth testing. I don't know how dumb they think their viewers are. I know Adam and Jamie have pretended to not know what it takes to set off C4 for the purposes of a myth test.
Then the plane will take off even without the propeller, duh! You're doing the work it does!
@@reliantncc1864
*"I don't know how dumb they think their viewers are"*
You' be surprised at he amount of discussion ensued by this topic at the time. A fairly large number of people actually thought that the airplane should not move.
it would but it would still take off
@@reliantncc1864 its a show dude most if not all the myths can be busted or confirmed with science but than you're just getting a lecture nobody wants to watch that
My understanding is that only the air speed is matter, the speed of air flow against wings. The air flow speed between the top and bottom of the wing surface creates the different air pressure and in turn creates the upward force to lift the plane. A standing still airplane will take off if it is facing a big fan blowing air by 25 miles per hour. In the normal taking off situation, the ground speed (wheel speed) match air speed; if in the tail wind direction, the ground speed will be much more than 25 miles to take off; in head wind, may be 15 miles will take off.
For simplicity,the wheels can spin faster than take off speed since they are freely rotating.
43:50 Shouldn't it be "With less than a guff of air movement, you could say the Mythbusters _haven't_ broken wind" ?
Still never understood how a plane could take off without wind passing over/under the wings to provide lift.
It can't. You need air flowing over the wing to create lift.
The point of the myth here is that you are still getting wind across the wings. The plane doesn't drive the wheels, they spin freely. So even if you've got a conveyor belt traveling the opposite direction at the speed of sound, once the airplane gets its propeller going, the ground's speed doesn't matter. The propeller pulls the plane forwards.
The only way to stop a plane from taking off this way is to actually prevent its *wings* from being able to move forwards, like with posts or something.
Also, we can't just use conveyor belts to shorten runways for much the same reason. What the plane "cares" about is the speed of the air running over its wings, so unless we shorten the time required to get up to that speed, we won't shorten the distance required.
@danriehl4244 I understood the part about the wheels being free-spinning and the propeller creating the forward moment. What I'm not so clear on is how the air would move across the wings if the plane wasn't moving relative to the ground or the air around it.
If I run on a treadmill, I don't get a breeze moving across me because I'm not moving relative to the air around me.
@@infamoushacker4chan883you aren’t moving forward on the treadmill because you’re pushing off the treadmill at the same speed the treadmill is moving.
The plane moves because it’s pushing off the air not the treadmill, so as it pushes the air it moves forward on the treadmill, its wheels start at the same speed as the treadmill and accelerate faster than the treadmill as the plane gains speed from pushing off the air, increasing wind across the wings, until it takes off.
Make sense now?
@infamoushacker4chan883 oh, I see what you're getting at now.
The only thing that matters to become airborne is the speed of the air over the wing. Light aircraft need to be anchored when parked outside because strong winds will cause them to lift off. Even jet aircraft can start lifting off the ground in high enough winds.
The Wright brothers referred to their Flyer as a kite, because it was essentially a giant box kite. The word airplane hadn't been invented at that point. And like any kite, if you have a strong breeze, all you have to do is hold it into the wind for it to take flight. If it's not very breezy, you'll have to run for it to catch enough air to take off. The propeller is just a tiny wing spun fast pulling the craft forward with air instead of traction on the ground. Helicopter blades are just giant props pointing up, eliminating fixed wings.
IMO, it all boils to is the power source able to generate enough air flow under the wings.
think abt this, the power source (propeller/jet) job is to pull/push the plane forward so that the air flow speed is increased to the extent the lift is generated greater than the weight (thrust to weight ratio)
Assumption: the conveyer speed matches the take off speed of the plane and no winds.
so the only consideration (ignoring the precession) is if there is airflow under the wings. this would be dictated by where the propeller or engine is located
a. In front, the propeller or jet pushes the air towards wings. more effect in case of propeller since air flow grows as funnel so it covers more wing area whereas jet airflow is more like a high speed stream concentrating only some cross section of the wing.
This will create the required airflow to create lift. Once the wheels lose contact with belt, it is under its own power and will fly forward.
b. If the engine is at back , does it pull in enough air to lift the wings? usually incoming air's speed while taking off is lower than the 'thrust', why else would planes need extra power.
so the if the propeller/jet is at back not enough airflow is generated to lift wings at the set take off speed
Your analysis becomes faulty. You start well; _"...it all boils to is the power source able to generate enough air flow under the wings"._ lift is generated by airflow over the wing; when the lift is greater than the weight, the 'plane lifts from the ground. It doesn't matter significantly where the propellers are located as long as they can generate enough thrust to push the 'plane forward fast enough. 'Planes with propellers at the rear at called "pushers', and propellers at the front are 'pullers'. The Wright brothers first 'plane was a 'pusher'. The propellers were behind the wings. Successful 'planes are still being built and flown with propellers, or jets, at the back. So the analysis about pullers' vs 'pushers' reaches erroneous conclusions.
Further, if you watched the video, you will see that both the model and full-size 'planes are 'pullers' with their propellers at the front, and they both can take off from solid ground powered purely by their propellers.
You can find many examples of ''pusher' aircraft by searching the web. One of the 'planes which could take off from runways located at unusually high altitude (which is harder than at sea level) was a 'pusher' called the BA VC-10.
Some of the experimental or prototype 'planes which are intended to use fuel much more efficiently are 'pushers'.
The speed of the conveyor belt is irrelevant. The 'planes wheels are freewheeling, and contribute no thrust.
Best Wishes. ☮
The airplane Sketch is just crazy the treadmill can't have any effect because the source of thrust is independent on the airplane … So treadmill or no treadmill the airplane will go forward no matter what…
How on earth did people genuinely believe that the airplane wouldn't take off 🤦♂️
The only thing the conveyor belt is moving is the wheels. These can be spun at very fast speed with hardly an power at all.
As soon as the aircraft moves forwards, it comes off the conveyor then takes off in the same distance it always takes.
Why are the bugs not radioactive, but the equipment used for cleaning disasters (clothes, tools, etc.) are?
Equipment used for cleaning [radioactive] disasters get contaminated (picks up) the radioactive material. The bugs never come into contact with the radioactive material, only the radiation.
Best Wishes. ☮
Its frustrating that they even had to test plane on a treadmill. Aircraft ground speed means nothing to flying, only air speed matters since that is what generates lift on a wing. A Cessna would do a vertical take off and landing in an 80kt wind (ground speed zero if flying into the wind, or would have a take off and landing ground speed in excess of 130kts if flying with an 80kt tail wind but either situation simulates the same physics since moving the air and stationary ground is equivalent to moving the ground beneath stationary air.
Even more frustrating that the pilot was surprised it works.
You'd think they would put a lead door or something to separate the researches from the radiation, but no, its just a line on the floor xD
Most of the time, you just need to reflect the radiation back into the room. The fact that they handled the insects with no real protection means they weren't hit with particle radiation. So the source can be reflected like light. They probably would be fine to cross the line, but they might have a safety cutoff that detects someone heading into the room.
Steve Henry’s plane would take off before it’s halfway down the conveyor belt
I have to say the plane on the conveyor belt confuses me. The lift doesn't come from the engine or the wheels, but the air flowing over the wings from moving forward. If the conveyor belt is moving in reverse at the exact same speed, it shouldn't matter that the engine is pulling the plane forward because the conveyor belt should be pulling the plane back at the same speed, so the plane should stay put. The plane wasn't taking off on a conveyor belt but getting enough traction on the solid ground beneath the conveyor belt tarp to allow it taxi down the conveyor belt, regardless of the belt moving under it. I keep hearing Jamie talking about the engine runs the propellor, but that should make no difference if the plane is truly trying to take off on solid ground that is moving with the wheels. I'd like to see this test again on a conveyor belt that is made of solid slats so that the plane can't get traction from the ground under it and see what happens.
the wheels spin freely unlike a driving car so pullinbg the tarp just causes them to spin faster but the motion of the air does not change and the plane uses the air to move. Imagine it was you with rollerblades on with a railing that was still you could use to pull yourself. the tarp could move but when you pull on the railing you still move forward even if the tarp is going the other way. The air is the railing for the plane. If you wanted the plane to stay still you would need a wind tunnel pushing air against the plane but even then it would still take off just not be able to move
Why do the mythbusters always destroy nice cars 😭😭😭
Pilot Mark specifically stated if there is no air over the wings it will not lift
R.i.p. Grant 😢
I never understood people thinking that the plane wouldn't make it the only extra force you have is the bearings for the wheels (which isn't much)
The airplane "myth" is obvious!
The only force retarding the craft is wheel-bearing friction, which is tiny, plus the treadmill will help the aircraft a bit by creating airflow under the wings, creating lift.
If anything, a plane on a treadmill should take off earlier!
They do! I used one to launch a RC airplane that isn't able to take off under its own power when I was a kid (you were supposed to throw it with one hand and then remote with the other).
It's like a slower version of aircraft carrier catapults. So obvious.
@@reliantncc1864 But wheel speed has absolutely nothing to do with the planes ability to take off
@@VashStarwind Exactly.
The RC club I’m in ran the plane on a conveyor belt experiment in November 1999. We were able to prove without a doubt that the propellor forcing air over the wings causing lift is what makes the plane take off. A plane tethered with 50 foot of fishing line staked to the ground and stretched out was able to take off and hover without ever moving forwards. It took 2 attempts with an experienced pilot to get it to hover at about 10 feet. On the 3rd attempt the fishing line was cut as the pilot applied power and it gently propelled forward as it rose into the air more. We actually took a photo with the club members standing under the plane while it was hovering. We also tried same experiment on a treadmill and the results were no different.
2 months later a jr member asked would the results be the same if the treadmill was ran in the opposite direction, so once again it was all set up and turns out as long as airspeed over the wing is correct the plane simply went straight into a hover at approximately 10 feet.
Correction: it's not the propeller forcing air over the wing that causes it to climb. The propeller pushes air back, resulting in a thrust force, which accelerates the aircraft. Acceleration leads to increase of airspeed, which gives lift. You are talking about 3D planes and hovering, which is in fact high-alpha operation. In that case, the propeller generates enough thrust to lift the airplane off the ground without airspeed. The experiment isn't about that.
The ground and wheel speed have nothing to do with the wings making lift ! When the wing has air moving past the wing above stalk speed, the plane will fly. Those wheels and ground will have no effect.
Remote Controlled Aeroplane Shenanigans? It’s called Plane On A Conveyor Belt, guys! If you’re gonna post the episode online, at least title it correctly
So we talked all about radiation but didn't mention Marie Curie once?
Wings have to have air flowing over them to crate lift, so no it will not work.
I freaking love Mythbusters! But the roaches… might have to skip this one lmao
I miss those old and fragile GWS planes
Now give jimmy a red doubledecker or trippeldecker
You lift your feet on a treadmill. A remote control car has resistance to match energy. A plane shouldn't have any resistance unless your brake drags.
Find the laughing 😂 jack ass in this video 📹 😊
I have seen a cockroach fully survive being cooked in a microwave oven.
It wouldn't work
I haven't seen the full video yet, but I'll say it right now that speed isn't a factor of obtaining lift
It takes air moving around the airfoil in order to get lift
If you just run a plane on a conveyor belt, it can't achieve lift because no air is going around the wing
The model plane didn't get lift, its engine just allowed it to move faster than the treadmill
If you had a conveyor belt that could speed up to whatever speed required, could you theoretically have a plane vertically take off from the conveyor belt?
Nope. It could be statically vertical relative to the belt, but not to the ground under the belt. No airflow/airspeed, no flight.
@ ah I should have explained better. I meant like those dog treadmills yknow? Where it could speed up with the plane as it accelerates.
Is the treadmill myth trying to debunk what causes lift?
I have no idea. It's a dumb question and a simple problem.
The pilot was surprised that he could take off at the same velocity he always takes off with. Back to school for that guy.
46:11 his face reads "maybe i shouldnt have said that and im gonna eat my words"
he didnt though, the plane was moving faster than the conveyor belt
The problem here is that the question is under defined.
Interpretation 1: The conveyor belt moves at a speed v (relative to the ground) backward equal to the forward speed of the plane relative to the ground.
No problem plane takes off. The wheels just spin twice as fast as they would otherwise.
Interpretation 2: The conveyor belt moves backward at a speed equal to the velocity of the plane relative to the conveyor belt.
But if you work out the math that means that the plane must be standing still relative to the ground ... in other words you keep speeding up the conveyor belt until you bring the plane to a stop relative to the ground. As long as the wheels of the plane aren't completely frictionless this is always possible and the plane obviously can't take off.
Yeah I kind of assumed they were going to keep matching the planes speed on the belt, but I guess that would be hard to do. Kind of a trick question type of thing..
@ Yea, though TBF it is matching the plane's speed relative to the ground so it's not delibrately a trick question just one with two reasonable interpretations.
The problem with theory 2 is that spinning wheels that fast would cause a wheel failure long before you stop an airplane from taking off. The thrust being produced is independent of the wheels, it’s like your car being in neutral on a conveyor belt. The wheels will spin just as fast as the conveyor belt is but if you but a jet engine or propeller on top of your car then you will move forward. So yes it is TECHNICALLY possible, but not what would happen in the real world.
@ Depends on how much friction is being produced by the wheels when they spin. Especially for a small plane those wheels aren't made to minimize frictional losses so while you would no doubt eventually get a failure due to heat buildup it certainly wouldn't happen immediately. There would be some non-zero period of time where it prevented take off.
But this is all a bit besides the point because it's a thought experiment. I'm perfectly happy saying that if you idealize friction to be zero in interpretation 2 you can't satisfy those conditions but that's just not the same thing as saying the plane can take off if those conditions are met.
The airplane accelerates to take-off speed, relative to the ground, and takes off. The wheels are 'freewheeling'. It really doesn't matter what speed the conveyor belt is moving.
A solution to "Interpretation 2" is to move the conveyor belt *_in the same direction_* as the 'plane is moving, *_maintaining the relative velocity between 'plane and conveyor belt at 0_* That fully satisfies the requirement _"The conveyor belt moves... at a speed equal to the velocity of the plane relative to the conveyor belt"_
_"If you work out the maths"_ that is a valid solution. Clearly, the 'plane does *NOT* need to be standing still relative to the ground.
Best Wishes. ☮
How a pilot could believe he wouldn't be able to take off really surprised me. The myth itself seemed pretty dumb to begin with. The plane is disassociated with the ground. It's speed relative to the air around it is really the only factor. The drag a conveyor belt would impart to the planes wheels would be neglagable. You have to have no understanding of what is going on to think it would change anything and at that point, you know so little that even arguing strongly with someone about is dumb since you don't understand what is even happening
Notice how he says "if there's no air over the wings". The scenario in his mind is one where the conveyor has caused enough drag via the wheels to cancel out the thrust and make his speed relative to the surrounding air 0.
That's not the myth. The myth is that a conveyor which is itself moving backwards at takeoff speed would be able to prevent the plane from achieving flight, which clearly isn't possible because the drag from the wheels is nowhere near as strong as the engine thrust.
Or maybe he was playing dumb in front of the camera 🤷
@@nathanromero3430 I really hope that's the case. I can't see a professional pilot not understanding how his plane works so your probably right. Just to add some tension or drama for tv
@@whothef4900 ya maybe
man how tech has changed lol
The thing nobody ever talks about with the plane myth is that the WHEELS on the plane will be spinning twice as fast when it takes off - the speed the plane is moving forward PLUS the speed the conveyor belt is moving backwards. Maybe that will help people understand it more, because it’s not like the conveyor belt has no effect. The effect is just on the wheels only, not on the plane itself. You’d be able to drive forward with a car on a conveyor belt as well, IF you move the car wheels faster than the conveyor belt.
In a car you’d need drive the wheels twice the speed of the treadmill to continue forward at the same pace. The engine of the car drives the wheels. In a plane, the propeller pulls the whole craft, so the wheels will spin at whatever speed they need to spin, as long as they touch the ground. The ground is (virtually) irrelevant to how the plane moves through the air
@@Rad_Dan I don't know if you're trying to refute something that I said, but if you are, I think you're missing my point. I understand this myth, why people think the plane can't take off, and why they are wrong. I'm also aware of the difference between "driving wheels" (like on a car, connected to an engine) and "free floating" wheels (like on a plane), which just spin when touching the ground. What I was trying to add to the conversation is that the people who don't understand that the plane can take off seem to think something along the lines of "but that can't be true, because the conveyor belt must have some effect". My point is that the effect is on the WHEELS of the plane, which has no effect on whether the plane can fly, but most people discussing this myth don't seem to point that out. So my thought is that perhaps people would find this easier to understand if they note that the wheels on the plane, on the conveyor belt, would be spinning at twice the normal speed, so the conveyor belt has an effect (on the wheels) but that doesn't affect the forward speed of the plane. Hope that clarifies my point.
@@johnmaher5887 I get what you’re saying, I didn’t at first but with your follow-up comment I can tell that you were just trying to explain why the wheels would spin twice as fast to someone who maybe didn’t understand why, then complained that the “treadmill didn’t match the speed” or something like that. I had a bit to drink last night, and should’ve stayed off of UA-cam’s comment section lol, I hope you have a good one my friend
I understand why, but I'm still not convinced with the plane take-off. It still has forward movement. If it 100% stayed stationary, then took off, I'd be convinced.
you're missing the entire point. The reason the myth doesn't work is because pulling the tarp back doesn't keep the plane stationary it just speeds up the wheels
@ghostrunner2138 That makes sense!! I let that go over my head... Lol. Thanks for clearing that up for me!!