Who's ready for the new mythbusters?

Will it take off?

  • Yes!

    Votes: 36 57.1%

  • No!

    Votes: 27 42.9%
  • Total voters
    63
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Dan said:
Depends on the length of the runway, and whether you consider landing to be stopped relative to the ground or relative to the earth. The planes wouldn't be able to use wheel breaking to slow down once on the tarmac, but the engines can provide reverse thrust which would allow it to stop.
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Depends on the plane more than anything, and I had a picture of a jumbo jet in my head. The point I was [unconsciously] making is it wouldn't matter. Jets use air brakes in the wings to create excessive drag through lift (whilst moving at a speed too slow to lift the plane). Wheel brakes are applied later when speeds are much lower. The wheels would stop moving as they touched the ground (actually they would never be moving in the first place) and the conveyor would slow as the jet slows via wind resistance. I think this scenario is a little easier to understand even though it is simply the opposite of taking off.
It was just a silly question anyway, I hadn't intended to go anywhere with it.

The real question is, if I were on a treadmill that matched my speed (of wit), would I be able to go anywhere? :laugh:
 
_Z_Ryuken said:
The real question is, if I were on a treadmill that matched my speed (of wit), would I be able to go anywhere? :laugh:
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Yes, you would. Very easily. Just make leaps.

Because walking is not the same as using wheels to move.

We take a leap on the treadmill, we leave contact with the belt and are in the air, moving forward. We get all our momentum before we start moving so that the conveyor can't cancel our speed. Then the belt would be moving under you, you'd be in the air, then you land further than where you started, the belt stops again. Rinse and repeat.
 
OK... a plane doesn't get into the air cuz the engines suck in air and blow it out or whatever.. The whole point of flying is ***BLOCKING THE MOVEMENT OF AIR***. Since there is no wind resistance, the plane won't fly. There is no motion from either the plane nor the wind, so there is no collision, thus no resistance, thus no lift. This is like asking if a rock could fly if it had wheels and was on a treadmill.
 
lame-o said:
OK... a plane doesn't get into the air cuz the engines suck in air and blow it out or whatever.. The whole point of flying is ***BLOCKING THE MOVEMENT OF AIR***.
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woa... ... ...I hope you're joking.

Planes don't fly because they "block air"...they move because air IS sucked in one side and pushed out the other, and they fly because of a pressure difference between the top and bottom of the wing that occurs with fast(er) moving air.

edit for pictures!
wingairflow.gif
 
People don't seem to understand the concept of a turbine. (or lift^)

For anyone not getting this, what do you think will happen if instead of a plane, we had a glider with wheels, mounted with a rocket?
 
Yeah, I never said it wasn't a propulsion system (I think I know why a ****ing jet engine exists thank you very much) I meant it's not what makes the plane lift up and fly. And then you even went as far as to say exactly what I said... Thanks. What do you think wind resistance is? Just.. wind.... resisting...? That's what CREATES that pressure.
 
_Z_Ryuken said:
For anyone not getting this, what do you think will happen if instead of a plane, we had a glider with wheels, mounted with a rocket?
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It wouldn't fly. The fuselage would be too weak and the wings too flimsy to take the necessary acceleration from the rockets to generate life. Also, glider's already have wheels, so you now have an extra set of useless wheels superficially mounted to a glider creating more drag. Also, the added weight of the rockets would throw off the balance and control of the glider.
 
lame-o said:
What do you think wind resistance is? Just.. wind.... resisting...? That's what CREATES that pressure.
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Uh...no...low pressure in this case is created because the air traveling over the top of wing is moving faster than the air traveling under the bottom of the wing. Faster moving air creates a low pressure system, so the higher pressure from underneath the wing pushes up.

Wind resistance creates...resistance. Which is exactly what you want to reduce in an airplane, because then it would increase efficiency and therefore decrease operating costs.
 
oh well, i don't know the proper meaning of the word then, but I thought I still made it pretty clear that I meant movement of air against the bottom of the wing... so the plane has to be slicing air for that to happen, because if it stands still, the wings stay still - surrounded by unaffected air. Simple enough, if you can't get that you fail. Excuse the poor word choice though?
 
Dan said:
It wouldn't fly. The fuselage would be too weak and the wings too flimsy to take the necessary acceleration from the rockets to generate life. Also, glider's already have wheels, so you now have an extra set of useless wheels superficially mounted to a glider creating more drag. Also, the added weight of the rockets would throw off the balance and control of the glider.
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The question of whether not it will fly is not the point he was trying to make. The fact is that it would move forward because the rocket is pushing the air, not the treadmill.

lame-o, you're making the same mistake everyone else is. The plane IS moving through the air.
 
Dan said:
It wouldn't fly. The fuselage would be too weak and the wings too flimsy to take the necessary acceleration from the rockets to generate life. Also, glider's already have wheels, so you now have an extra set of useless wheels superficially mounted to a glider creating more drag. Also, the added weight of the rockets would throw off the balance and control of the glider.
Click to expand...

If the rocket were mounted internally with it's own subframe supported by these extra wheels (among other things), there is no problem. ;)
Flying isn't the objective though, the objective is to show a simple conveyor cannot hold an accelerating object in place. :laugh:

The problem isn't these people do not believe a plane can fly, but they do not believe a plane can overcome a treadmill. :|
 
_Z_Ryuken said:
The problem isn't these people do not believe a plane can fly, but they do not believe a plane can overcome a treadmill. :|
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Well in an ideal world. In reality, you have bearing friction, which is typically linearly related to plane weight. But then you also have the movement of air caused by the noslip condition at the surface of the treadmill. (The treadmill will be pulling air along with it). If the treadmill is infinite, you can apply the Navier-Stokes equations to determine the speed of this air. If it is not infinite, the plane will probably be in the turbulent zone, and there are equations which can solve for that too. What this means is that if you get the treadmill moving fast enough, you will generate an aerodynamic drag force which increases with the square of the treadmill velocity on top of the rolling resistance.
 
Bearing size is also related to plane weight. Heavier planes have larger higher grade bearings. There is greater friction overall, but far fewer rotations.
I do see your point about noslip condition creating a drag force, but aircraft have a constant lift velocity and it would be achieved long before the treadmill could ever generate the speed required for this drag to become effective if it is expected only to match the planes ground speed.
 
Dan said:
I don't watch a whole lot of myth busters, but their experiments I have seen which piss me off because of the stupidity of their experiments I can recall:
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If you are watching Mythbusters for scientific accuracy then you are watching it for the wrong reason. The busting of myths is just an excuse to do cool things and have a good time, at least that is why I watch it.
 
Which is why everyone has said over and over again how a plane ISNT like a car.
 
Somebody once told me that Bernoulli's equation (difference in velocity of wind generates pressure difference which creates lift) is only part of the reason for lift. Can anyone confirm/explain that?
 
Internet: Pointless debates abound!
 
Ridge said:
1201248317303kr5.jpg
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Hahahahah. Genius.
Baal said:
The way I see it, the location of the aircraft does not actually change in relation to the surroundings.

Surroundings include air

If the aircraft does not move into the air, or the air does not move into the aircraft (wind), there is no resistance, and there is no flight.
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Quoted for truth.
 
Vegeta897 said:
The question of whether not it will fly is not the point he was trying to make. The fact is that it would move forward because the rocket is pushing the air, not the treadmill.

lame-o, you're making the same mistake everyone else is. The plane IS moving through the air.
Click to expand...

Rockets don't push against air. They push against their own mass.
 
Vegeta897 said:
MythBusters always does the most stupid-ass non-scientific approaches to "busting myths", it makes me want to shoot myself every time I watch. They always make these dumbass conclusions based on like 3 experiments where they completely change every variable in each one.

And they always build some ridiculous unnecessary thing because they have budget to throw around I suppose. And to get more viewers.
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Wow

You're angry
 
Vegeta897 said:
Yes, you would. Very easily. Just make leaps.

Because walking is not the same as using wheels to move.

We take a leap on the treadmill, we leave contact with the belt and are in the air, moving forward. We get all our momentum before we start moving so that the conveyor can't cancel our speed. Then the belt would be moving under you, you'd be in the air, then you land further than where you started, the belt stops again. Rinse and repeat.
Click to expand...

Thats wrong. Running is a similar method of propulsion as spinning tires. What you're explaining wouldnt actually happen, because when you're running on a treadmill, you're not actually moving in world space. You have no world space momentum, and thus when you jump, you wouldnt move forward at all in world space. The only forward movement you would have when jumping would be relative to the belt on the tread mill, which is the same as running forward on the machine.

And to everyone else... the plane WILL TAKE OFF. The difference between a human running, a car driving, and a plane taking off is the type of thrust. Planes have either propellers, jet, or turbine engines. These force the body forward on free spinning wheels. Cars have engines that spin the wheels which push the car forward on a non-moving surface, same with people who use their legs to push them forward on a non-moving surface. It is for this reason that ONLY the plane will move forward on the conveyor belt thanks to the free spinning wheels.

The ONLY possible reason which might stop it from taking off is the friction from the tires slowing down the plane's forward, world-space movement. IF that friction is enough to slow the plane's forward movement enough to reduce its world-space speed to a point where the lift isnt enough to bring the plane off the ground, then it wont take off.

But it WOULD NOT be because the plane is stationary, because there is no way the conveyor belt would be able to prevent the world-space forward movement of the aircraft. Period.
 
Come on guys, the plane would take off because it's a plane. That's what it does.
 
99.vikram said:
Somebody once told me that Bernoulli's equation (difference in velocity of wind generates pressure difference which creates lift) is only part of the reason for lift. Can anyone confirm/explain that?
Click to expand...

Another important reason is the Coanda effect. Fluids stick to a curved surface as they go over it. That means that that as long as the flow doesn't separate, the wing has to be pulling the fluid down to keep it attached, and by Newton's 2nd law, the fluid is also pulling the wing up.

The other reason, is the angle of attack and the direction of air right behind the wing. The wing pushes fluids down at the back end, both because it is coming over a curved surface, and because the bottom surface is angled into the wind a little bit.

Que-Ever said:
Why the **** would a plane be on a treadmill.
Click to expand...

Because it made a New Years resolution to get in shape.
 
I have a treadmill about 4 feet from my computer. When I get back from work, I will test the "can you jump forward while running on a treadmill" question. /laff
 
Vegeta897 said:
The question of whether not it will fly is not the point he was trying to make. The fact is that it would move forward because the rocket is pushing the air, not the treadmill.

lame-o, you're making the same mistake everyone else is. The plane IS moving through the air.
Click to expand...

How the hell is it moving through the air? The only thing in motion is the track and the wheels, everything else is still. Is the track magically pulling air against the front of the plane now? Has the plane been transported to another dimension where air is glued to the track? There might be a slight movement of air a millimeter above the track because it is moving through space and pushing the air around it, but other than that there is absolutely no movement.. because the plane itself is not moving through any space, and the air isn't either (unless you count natural air currents which couldn't possibly move the plane.. unless it was a hurricane) I mean, you're saying here that planes can lift off the same way helicopters do.. just because the wheels are turning?

You don't ever hear of really light cars (rally cars, f1, what have you) going so fast on engine tests (where all 4 wheels are on a moving track) that they suddenly lift up and flip over. And technically if they were actually moving at the speeds they test them at they could flip, thats why they make cars aerodynamic.
 
lame-o you are still missing the point about the wheels and you are still thinking of how a car works and not a plane. once you understand that then i think you will know the answer.
 
lame-o said:
How the hell is it moving through the air? The only thing in motion is the track and the wheels, everything else is still. Is the track magically pulling air against the front of the plane now?
Click to expand...

the track, the wheels, AND THE TURBINES IN THE ENGINE.


I still don't think you understand how a plane works. The track is not pulling air against the plane. The engines are sucking in air from the front and pushing air out the back...THEN the plane moves forward, THEN the air 'magically' goes over the wings.
 
lame-o said:
How the hell is it moving through the air? The only thing in motion is the track and the wheels, everything else is still. Is the track magically pulling air against the front of the plane now? Has the plane been transported to another dimension where air is glued to the track? There might be a slight movement of air a millimeter above the track because it is moving through space and pushing the air around it, but other than that there is absolutely no movement.. because the plane itself is not moving through any space, and the air isn't either (unless you count natural air currents which couldn't possibly move the plane.. unless it was a hurricane) I mean, you're saying here that planes can lift off the same way helicopters do.. just because the wheels are turning?

You don't ever hear of really light cars (rally cars, f1, what have you) going so fast on engine tests (where all 4 wheels are on a moving track) that they suddenly lift up and flip over. And technically if they were actually moving at the speeds they test them at they could flip, thats why they make cars aerodynamic.
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By your logic, the runway must be pushing air under the plane by itself during normal take-offs, since apparently the plane cant move air by itself.

The air IS moving through space because the plane's propulsion is moving it, be it a propeller, jet or turbine engine.
 
The jets increase speed, yes. Speed is what the plane needs to have enough force from the air to push it up. But you're forgetting a simple rule of physics, if one force is pushing an object back by X m/s, and the object is moving at a velocity equal to the the force in the opposite direction, the velocities cancel out and the object gains a total velocity of 0 m/s. Since the track is pushing the plane in the opposite direction at exactly the same velocity as the plane is moving, the jets really don't matter.

Jet engines don't put air over the wings of a plane considering they're either UNDER or BEHIND the god damn wings, or basically just out of the wings' way.

The Wright brothers didn't even have propellers/engines/whatever and it still flew. You show me a turbine on the first plane. They flew by dropping off a ledge didn't they? So tell me how the **** dropping off a ledge at a high speed with a plane is supposed to do anything according to your logic of turbines?
 
God damnit. Learn how a plane works and dont come back here until you see how wrong you are.

:P
 
Why? A plane would still fly if it didn't have engines, you'd just need to accelerate it to whatever land speed is needed for it to lift off.
http://memory.loc.gov/master/mss/mwright/04/04003/0030d.jpg

Do you see a ****ing TURBINE there? Wind, that's what it's ALL about. Period. And you create a sort of "artificial" wind when you gain speed. Like throwing a piece of paper in the air.

And when you aren't actually pushing against the air (therefore having no SPEED) you don't create this "artificial" wind and you don't ****ing lift off, and although those damn TURBINES help, a plane was not designed to be supported completely by the TURBINES.
 
You're talking as if the wheels have any effect on the plane's forward world-space movement beyond providing a insignificant amount of backwards friction. The wheels on a plane are FREE SPINNING. All the conveyor belt would be able to achieve is making the wheels spin faster than normal while the plane takes off.

Seppo said:
Dude...it's not "Ba-dum-bum-CHING"

It's just Ba-dum-CHING
Click to expand...

Google's auto-complete said otherwise.
 
ok then, so lets get rid of the wheels on a plane and see what happens when it tries to lift off.
 
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