Mythbusters plan to uncover plane on conveyor belt

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simplified
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1:41p, 10/24/07
AG
Tying a string to the plane is completely different than the problem we're discussing. Ugh.

CDUB, could you throw in a few "die"'s for me, please?
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CDUB98
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1:41p, 10/24/07
AG
quote:
However, if the treadmill speads up to the exact speed that you pull the skateboard forward it will stay in place.


no



it


will




not
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IIIHorn
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1:41p, 10/24/07
Airplanes take of everyday from landing strips which would be the equivalent to a conveyor belt which has the velocity of 0.

Start the conveyor belt, and increase the velocity. The wheels will just turn faster than normal.

This is not a difficult concept.

The conveyor is moot.

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MonkeyKnifeFighter
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1:42p, 10/24/07
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coltjimclemens
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1:44p, 10/24/07
quote:
MonkeyKnifeFighter
posted 12:42p, 10/24/07




quote:
--------------------------------------------------------------------------------
However, if the treadmill speads up to the exact speed that you pull the skateboard forward it will stay in place.

Do you see what I am saying; this is impossible though.
--------------------------------------------------------------------------------

Nooooooo!!!!!!!

Hell, set the treadmill at 50 mph. You can still pull yourself forward with almost the exact same force as if you were standing on the ground pulling yourself forward.


You are missing my point, I am done with this thread.

In reality it will take off.

Theoretically it will not.
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NeuroticAg
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1:44p, 10/24/07
AG
You can certainly tell the difference between the engineers who mostly deal in the tangibles and theorists who are willing to think beyond the possible.
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coltjimclemens
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1:45p, 10/24/07
quote:
NeuroticAg
posted 12:44p, 10/24/07



You can certainly tell the difference between the engineers who mostly deal in the tangibles and theorists who are willing to think beyond the possible.

Exactly, however I am not an engineer.
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MonkeyKnifeFighter
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1:45p, 10/24/07
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IIIHorn
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1:45p, 10/24/07
quote:
You can certainly tell the difference between the engineers who mostly deal in the tangibles and theorists who are willing to think beyond the plausible.


fify
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TexasRebel
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1:45p, 10/24/07
AG
quote:
Start the conveyor belt, and increase the velocity. The wheels will just turn faster than normal.


unless the conveyor is trying to match the wheel speed...

and x is trying to catch up to x+y where x greater than 0 and y is not 0.

or

x ?= x+y where 0<x and y!=0

which is ALWAYS FALSE!

the conveyor will continuously acclerate and like NA said...if the tires and bearings are unmeltable...friction will eventually overtake the plane...

...a situation that is impossible to test.
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92Ag95
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1:46p, 10/24/07
AG
The only thing the conveyor does by moving opposite from the direction of the plane is to increase the rotational velocity of the wheels as the plane takes off. It should not affect the speed of the plane with respect to the air.
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IIIHorn
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1:48p, 10/24/07
quote:
the conveyor will continuously acclerate


Which will do nothing but effect wheel rpm.


Nothing more.

The conveyor is moot.
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BrazosDog02
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1:48p, 10/24/07
AG
quote:
Tying a string to the plane is completely different than the problem we're discussing.


I agree, and i see that now. im not seeing how the hell a plane that has nothing to do with ground movement and everything to do with air movement can't take off.

What if the AIR was the conveyor and matching the plane 'speed' wise.
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simplified
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1:48p, 10/24/07
AG
quote:
Exactly. Assuming that you had unmeltable bearings, you could theoretically create enough heat to increase friction to the point where the plane would not take off.

so heat in an unmeltable bearing will enough to stop ~20,000 lbs of thrust?....
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coltjimclemens
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1:49p, 10/24/07
quote:
MonkeyKnifeFighter
posted 12:45p, 10/24/07




quote:
--------------------------------------------------------------------------------
Theoretically it will not.
--------------------------------------------------------------------------------

Then sadly you are leaving this thread with an incorrect understanding of why it will take off.


Under the conditions that I would like to see set up I do not believe it will take off. However my conditions would probably be too strict for mythbusters or reality in general.
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Slicer97
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1:49p, 10/24/07
AG
TAKE IT TO THE NERDERY!
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IIIHorn
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1:50p, 10/24/07
I like the thread right where it is.
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TexasRebel
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1:50p, 10/24/07
AG
quote:
so heat in an unmeltable bearing will enough to stop ~20,000 lbs of thrust?


no, but the rolling resistance of the "underinflated by design" tires will be.

Bearings are not actually "frictionless"...friction does increase with velocity.

same with wheels...espeically rubber inflated ones...like your car... that's why rail cars have steel on steel...very little rolling resistance... so little, in fact, that on a flat grade, you would have an easier time pushing a 100,000 lb boxcar than your Honda civic.

[This message has been edited by TexasRebel (edited 10/24/2007 12:52p).]
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MonkeyKnifeFighter
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1:51p, 10/24/07
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Tom Servo
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1:54p, 10/24/07
The conveyor is moot.

The thrust of the plane's engine will cause it to move forward until it reaches takeoff speed. The spinning wheels do not propel the plane.

Think of a seaplane. It does not have wheels. It's engine makes it move forward and skim along the water until it reaches take-off speed.

Same thing if the plane was on a sheet of ice. It's engine would produce thrust and cause it to slide forward until it reached takeoff speed, even though the wheels wouldn't be turning.

Thank you, thank you. Smartest man alive.
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coltjimclemens
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1:55p, 10/24/07
quote:
MonkeyKnifeFighter
posted 12:51p, 10/24/07



Colt, go back to my page #1 airport/fan solution. That matches your assumptions. The speed of the "aircraft" is the speed at which the conveyor is moving in the opposite direction. The fan will still roll forwards so that an outside observer off of the conveyor would see it going forward, not remaining stationary.


This almost addresses my issues. Honestly, I know it will take off under any conditions we can make, but I think that if done in the most scientific way possible (which is beyond anything that we can do right now) it would not take off.
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TexasRebel
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1:56p, 10/24/07
AG
quote:
Think of a seaplane on land. It does not have wheels, the engines must overcome the friction between the skids and the pavement


fify
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IIIHorn
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1:56p, 10/24/07
It will most certainly take off.

The only portion of the scenario affected by the conveyor belt is wheel rotation.
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TexasRebel
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1:57p, 10/24/07
AG
Just make the problem simple and say that the conveyor matches the ground speed of the plane...

which is actually a do-able experiment given a conveyor with enough horsepower.
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coltjimclemens
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1:58p, 10/24/07
quote:
TexasRebel
posted 12:57p, 10/24/07



Just make the problem simple and say that the conveyor matches the ground speed of the plane...

which is actually a do-able experiment given a conveyor with enough horsepower.


NOT EVEN CLOSE TO POSSIBLE!
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IIIHorn
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1:59p, 10/24/07
quote:
NOT EVEN CLOSE TO POSSIBLE!


Ground speeds of very light aircraft are not that great at take off.
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TexasRebel
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2:01p, 10/24/07
AG
give them a good headwind and they'll take off at < 100 mph...

there are windtunnel conveyors that run over 200 mph...

hth
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BrazosDog02
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2:04p, 10/24/07
AG
If you place a car on a conveyor, and push the car forward with your hand (while standing off to the side), it will still move forward, no matter how fast the belt moves, so the wheels just speed up a LOT, just like the others have said. is this a good analogy? If this car had wings, then the air speed across them would be increasing regardless of the conveyor, so it should take off....right>?
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coltjimclemens
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2:04p, 10/24/07
quote:
IIIHorn
posted 12:59p, 10/24/07




quote:
--------------------------------------------------------------------------------
NOT EVEN CLOSE TO POSSIBLE!
--------------------------------------------------------------------------------



Ground speeds of very light aircraft are not that great at take off.


Matching acceleration continuosly would damn close to impossible, no matter how low the speed is.
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IIIHorn
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2:06p, 10/24/07
I disagree.
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coltjimclemens
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2:06p, 10/24/07
quote:
jed1154
posted 1:04p, 10/24/07



If you place a car on a conveyor, and push the car forward with your hand (while standing off to the side), it will still move forward, no matter how fast the belt moves, so the wheels just speed up a LOT, just like the others have said. is this a good analogy? If this car had wings, then the air speed across them would be increasing regardless of the conveyor, so it should take off....right>?


Not a good analogy, you are not matching the speed of the accel to the conveyor

Damn it, now I am done!
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TexasRebel
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2:07p, 10/24/07
AG
find a definition of aircraft ground speed colt...
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IIIHorn
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2:07p, 10/24/07
The speed of the conveyor is meaningless.

Except for its relationship to wheel rotation.
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BrazosDog02
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2:09p, 10/24/07
AG
quote:

Not a good analogy, you are not matching the speed of the accel to the conveyor


eh....now im done too. I just dont get it i guess. Even if i match the speed of the plane with the conveyor, the wheels move even faster, but it still goes forward......
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IIIHorn
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2:11p, 10/24/07
Colt,

Please explain to me why the velocity of the conveyor belt is relevant.
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