The weight of the plane on the tarp creates a resistance force. The wheel still rolls on the ground through the tarp. No matter how fast the tarp is being pulled in one direction, as long as the plane is traveling in the opposite directuin and achieves a certain amount of air flow across the wing, it will take off. The tarp could have been pulled at 1.000 mph, it doesnt matter. It just matters how fast the air moves across the wing.

1/30/2008 10:34:04 PM

that's been said for 12 pages

1/30/2008 10:35:05 PM

Quote :

"No matter how fast the tarp is being pulled in one direction, as long as the plane is traveling in the opposite directuin and achieves a certain amount of air flow across the wing, it will take off. The tarp could have been pulled at 1.000 mph, it doesnt matter."

Except in the real world where things melt or break, but yes up until that point (probably closer to 200 mph) that's true. Yeah I know that's not the myth but damn it I wanted burning.

[Edited on January 30, 2008 at 10:36 PM. Reason : ]

1/30/2008 10:36:08 PM

The show proved that a plane can take off of a tarp being pulled in the opposite direction. I admit that. gg mythbusters.

1/30/2008 10:40:58 PM

how bout them roaches, that was the crazy shit to me

yuck, especially after watching dirty jobs earlier

1/30/2008 10:41:58 PM

why didnt they just show a clip of a plane taking off of a carrier and just end the show

1/30/2008 10:42:16 PM

Shhh... if the Mythbusters used either good, obvious, or symple methods of determining the validity of the myths they wouldn't have a show anymore Hell, some of the myths they had to revisit because they screwed up the first time they could have confirmed by reading multiple news stories and doing some FUCKING MATH (airplane+taxi.)

[Edited on January 30, 2008 at 10:45 PM. Reason : ]

1/30/2008 10:43:51 PM

lol. then everyone would just say the carrier wasn't going the same speed as the plane.

1/30/2008 10:44:37 PM

Water speed doesn't = ground speed doesn't = air speed

1/30/2008 10:45:23 PM

How about planes taking off from the ground? Rotational speed of the earth?! OMFG?! Look out for those cross products and greek letters.

[Edited on January 30, 2008 at 10:47 PM. Reason : ]

1/30/2008 10:46:24 PM

Yeah but the plane didn't have snakes in it

1/30/2008 10:50:31 PM

or they could have held the tail of a model plane and revved it up and let it go

/thread

1/30/2008 10:51:58 PM

what were those stupid things Kari was wearing on her hands?

1/30/2008 11:02:10 PM

this has prolly been covered, but a simple force analysis will tell you the result

the conveyor belt does not provide a force that resists the thrust of the propeller or turbine....all that force goes into spinning the tires

if the conveyor belt moves in the opposite direction with equal speed then all that happens is the tires turn twice as fast

at some point i guess you could move the belt fast enough to make the friction in the wheel bearings come into play, but then the tires would be turning so fast they would fly apart, the bearings would melt, yada yada yada



[Edited on January 30, 2008 at 11:05 PM. Reason : .]

1/30/2008 11:04:34 PM

but could a plane take off from the top of a waterfall?

1/30/2008 11:07:41 PM

a helicopter can take off from a moving truck that is falling over the edge of a dam

1/30/2008 11:16:25 PM

^^Sea plane?

1/30/2008 11:17:49 PM

yes, a sea plane

on top of a waterfall

facing away from the edge of the waterfall

does it fly away or fall over the edge?

1/30/2008 11:20:47 PM

OMGZ how does a sea plane take off if it doesn't have wheels and the water is moving against the plane!?!?!

1/30/2008 11:21:01 PM

EXACTLY!

SEE, THE PLANE DOESN'T GET OFF THE WATER!

1/30/2008 11:21:49 PM

it flies FORWARD and then UP

just like every other plane

1/30/2008 11:26:01 PM

EVEN IF THE OPPOSING WATER CURRENT > SPEED OF THE SEA PLANE??

1/30/2008 11:28:05 PM

^ yes, no matter what. as long as the friction is not so much that it holds the plane back

1/30/2008 11:51:29 PM

Quote :

"^ yes, no matter what. as long as the friction is not so much that it holds the plane back "

But forces from moving water aren't simply a friction force. There are linear and quadratic (increasing in dominance with greater velocity) elements to drag. So, unlike with a conveyer belt or treadmill, there is a noticeable and non-linear increase in the force on a plane with increased water velocity along the length of the plane.

[Edited on January 30, 2008 at 11:58 PM. Reason : ]

1/30/2008 11:53:24 PM

apparently winds in boone were bad enough today that a small plane at the local airstrip lifted off while sitting still and broke a window in some dude's jeep. or something.

1/31/2008 12:04:25 AM

should have parked it on a moving treadmill...

1/31/2008 12:07:52 AM

Or on a really really really heavy tarp.

1/31/2008 12:10:57 AM

this is why people believe in jesus

1/31/2008 12:45:02 AM

Is jesus a really really really heavy tarp?

1/31/2008 12:46:08 AM

page 13 says it doesn't take off

1/31/2008 12:48:29 AM

i like the segway with spinnas

1/31/2008 1:27:07 AM

so where's the youtube link? I want to see how it went. (I know it took off and all)

1/31/2008 7:06:46 AM

Quote :

"But forces from moving water aren't simply a friction force. There are linear and quadratic (increasing in dominance with greater velocity) elements to drag. So, unlike with a conveyer belt or treadmill, there is a noticeable and non-linear increase in the force on a plane with increased water velocity along the length of the plane. "

fine, but the principle is still the same. The thrust from the engines simply have to first overcome the friction at the interface of the water and plane, then provide more thrust to create speed through the air to take off. Same thing if the regular plane on the treadmill had a gimp wheel, or the brakes were on or something. as long as there is enouh trust to overcome the rolling friction then enough thrust to gain speed, everything is ok

1/31/2008 7:59:02 AM

Wow I'm surprised there aren't more trolls shouting about how they "messed up" the myth. I am not surprised that all the people claiming that it wouldn't take off seem to have completely disappeared from this thread.

1/31/2008 9:29:27 AM

Quote :

"they totally rigged the whole experiment. there's no way in hell that plane can take off because there's no windspeed over the wings "

1/31/2008 10:15:55 AM

it will not take off

this is a conspiracy by mythbusters to gain political power

1/31/2008 11:12:58 AM

Quote :

"fine, but the principle is still the same. The thrust from the engines simply have to first overcome the friction at the interface of the water and plane, then provide more thrust to create speed through the air to take off. Same thing if the regular plane on the treadmill had a gimp wheel, or the brakes were on or something. as long as there is enouh trust to overcome the rolling friction then enough thrust to gain speed, everything is ok"

But that's my point, with water it's not just friction. Planes don't magically float on top of water just touching the surface- they're going to displace some of it and be subject to drag. That means that unlike the treadmill there is a much more realistic speed for water at which the plane's thrusters would be simply overpowered. think of it as the difference between wearing rollerskates on a treadmill vs. having your feet in a somewhat shallow but fast-flowing white water current.

Something like this would boil down to the ability of the plane to achieve hydroplaning. It might seem that the water speed would be independent of this because all a plane would have to do was fight the current until it's skis or floats allowed it to climb out of the water enough to really accelerate- then it could start accelerating across the surface to flight velocity (like a water skiier first having to actually get up and skimming.) The problem is actually with the turbulence of the water. Extremely turbulent flow isn't going to be as simple to climb out of- something the plane has to do really before it can hope to achieve flight speeds. The plane might be able to do it, heck the RIGHT plane definately could - ie one designed to. Since I don't have access to CFD though, that would make a much cooler mythbuster experiment than the one they did.

1/31/2008 2:31:58 PM

im guessing that i somehow misunderstood the myth


now isnt the plane not supposed to move forward at all while on the treadmill if the treadmill and plane are going the same speed in opposite directions?

and so the whole point is that even though the plane is in the same exact location......the effect of the engine producing more windspeed allows for the plane to lift off without moving forward?

or someone explain where im wrong

if im right, then mythbusters did the myth wrong. the plane went forward ON the treadmill, which negates the idea that if they are both going the same speed...blah blah blah

because the plane is not going the same speed as the treadmill..........its going faster.


If the plane is traveling fast enough, enough wind will roll over the planes wings and create lift.

if the plane is in the same exact location while trying to take off.......its debatable if the engine can produce enough wind force over a portion of the wings......to create lift.


my conclusion is that the myth still remains and may work for certain planes depending on their weight
also, the mythbusters did it wrong.

but in speculation, i dont believe u could ever make the plane stay in the exact position because the engine will force the plane forward and the wheels will just spin even faster due to the movement of the treadmill and the plane.
such as the treadmill and the plane are going 50 mph, so the wheels are spinning as if they were going 100 mph. but they have no effect on whether the plane will stay in place or move forward. its all dependent on the planes engine.

1/31/2008 2:40:52 PM

wow

Quote :

"because the plane is not going the same speed as the treadmill..........its going faster."

tarp=25mph one direction, plane=25mph in the other, relative to the ground. total speed of wheels = 50mph, sure... i dont think you have a point though beyond that, the myth was done right, you just aren't getting it

[Edited on January 31, 2008 at 2:43 PM. Reason : asdf]

1/31/2008 2:41:40 PM

^^^ i suspect if you had a seaplane that was designed such that the skis had some kind of baffle sticking down in the water so as to my very un-hydrodynamic, then eventually the material connecting the engines to the baffle would fail. i don't understand how you think this would be any different from, say, tying a plane down by it's rudder and trying to take off. of course it's not going produce lift, it can't go forwards

the only thing that allows planes to take off is their ability to move forward. if you impede that, they cannot take off.

[Edited on January 31, 2008 at 2:43 PM. Reason : ]

1/31/2008 2:43:15 PM

see thats what im saying

if the treadmill is going 25 mph one way and the plane is going 25 mph the other way

the plane should be in the same spot


but what they measured was air speed, not ground speed like the treadmill is doing



so in reality the plane and treadmill are not moving at the same speeds

is the myth not synonymous with that if the plane stays in its exact location, even with engines at full power, the plane wouldnt take off.

[Edited on January 31, 2008 at 2:46 PM. Reason : ?]

1/31/2008 2:45:05 PM

groundspeed means jack shit. you could be stationary and have a positive groundspeed if you stood over a treadmill

1/31/2008 2:46:26 PM

What I was hoping for from this episode was not so much the physical demonstration which anyone with a lick of sense knew would happen, but that they'd spend more time explaining the physics of the situation so that any retard on the internet could understand what was going on.

People who believe the plane wouldn't take off will argue the Mythbusters' methods no matter how effective they were, but attempting to refute solid logic would be enough of a selfpwn that hopefully people would just start ignoring the naysayers

1/31/2008 2:47:16 PM

is the myth that the plane has a groundspeed or airspeed of whatever?

1/31/2008 2:47:30 PM

Quote :

"is the myth not synonymous with that if the plane stays in its exact location, even with engines at full power, the plane wouldnt take off."

i think the myth is basically a trick question...it's not meant to be a legitimate question, but rather to trick you into thinking a certain way. i dont have an example off hand, but there are plenty of scenarios that you completely and correctly understand, that if worded in the right way, could confuse the shit out of you. that's all there is to it really

[Edited on January 31, 2008 at 2:49 PM. Reason : ]

1/31/2008 2:49:29 PM

yea cause there are a lot of the myths that they do where they have to clarify exactly what the myth is. that there are subtle differences in some peoples versions.

so, no one really knows if its air speed or ground speed that the plane was supposed to be measured at. and if it was ground speed, it shouldnt have moved forward due to the treadmill. air speed, of course it would go forward, producing lift and flying

1/31/2008 2:52:41 PM

actually the groundspeed would have been 2x the airspeed, right?

1/31/2008 2:53:44 PM

ok, i have a perfect example

when flying a kite, if there is almost no wind..........you have to run with the kite to get it up

if there is enough wind, you can have someone just kind of release it into the air and it will have immediate lift.

so really with no wind, like the myth was tested at, the plane being kept in a stationary position even with the engine moving it forward, the treadmill keeping it in place. would not fly


now if u let it move forward, or run with the kite..........then your not really sticking with the rules

1/31/2008 2:55:31 PM

you don't need a plane, a conveyor belt, or anything to solve this problem

all you need is pencil, paper, and basic physics skills

1/31/2008 2:56:13 PM

You do realize that if you sit down with basic physics, all you have to do is match the acceleration of the belt to counter the force of the engines.

[Edited on January 31, 2008 at 3:01 PM. Reason : so it wouldn't fly.]

1/31/2008 3:01:23 PM