Poll: Mythbusters - Will the plane take off?

Just to throw fuel on the fire, remember this dad and his son from the last thread?

[yt]-EopVDgSPAk[/yt]
 
PCL_128 said:
The assumption is that there's a really long treadmill, so the plane has room to move forward.
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Most of the time I have been asked this question, the assumption was that the treadmill could match the speed of the airplane keeping it stationary relative to the ground and that the airplane is held stationary using a rope attached to the nose. In this scenario, lift cannot be generated (see math above) and the airplane will not fly. Even if you use the engine instead of a rope, it will not fly unless the thrust of the engine involved can vertically lift the entire mass of the airplane. Then you run into p-factor/torque problems (or perhaps you can add a tail rotor and call it a helicopter!).

Some might argue that the treadmill will cause a movement of air that will allow lift to occur. This will work until the airplane gets airborne and moves above the treadmill generated airflow and encounters the wind shear between this moving air and the relatively calm air above.

As for Mythbusters, they are advertising using a RC plane which may have a strong enough engine to let it take off on a short length of the treadmill, over come the potential wind shear when leaving the treadmill's generated airflow or it might be light enough to bounce occasionally and then call it flight! ;)
 
Acadia said:
Just to throw fuel on the fire, remember this dad and his son from the last thread?
Click to expand...

The question now is what myth are we busting? :P With a long enough treadmill and a powered takeoff, all you have to overcome now is the friction between your wheels and the surface of the treadmill. Takeoff is no problem!

edit: I should have read the other thread before posting! Doh!
 
This is absurd. I hope global warming takes place and wipes humans from the face of the earth because we are so unintelligent. The plane will most definitely takeoff and not because Mythbusters screws it up.
 
aerospacepilot said:
But this is such a simple topic, and I cannot understand why this topic comes up, and many people actually believe the treadmill will help in some way.
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Draw a free body diagram of a plane sitting on a treadmill. What force is opposing the thrust of the engine?

The treadmill cannot hold a plane stationary by sitting there and spinning the wheels.

By the way, no one is saying the treadmill will help, only that it can't hurt enough to prevent a takeoff.
 
gtpilot said:
Most of the time I have been asked this question, the assumption was that the treadmill could match the speed of the airplane keeping it stationary relative to the ground
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That's the entire point; a treadmill cannot keep the plane stationary. Since it can't keep the plane stationary, the thrust of the engine will move the plane forward.
 
Duh.jpg


Not a very good artist, but make of it what you will.
 
If it is held stationary the plane will not take off. Otherwise the plane will take off within the same distance it normally would. A treadmill has no effect on flight.

This would be comparable to putting a roller skate on a tread mill.The wheels will spin and at best it will stay stationary, otherwise it will move backward. Ever seen an airfoil move backward(hint: no controlled flight will occur)? The wheels have exactly zero propulsion and almost no friction(unless breaks are applied or the bearings are worn). They don't affect thrust one bit without outside forces acting on them.

As the question does not indicate engines running or what power setting both yes and no are correct, but no is more correct as there is only 1 way for it to fly(under its own power) and many more no's for it not to fly.

Simply setting the airplane on a treadmill will not make it fly.

<deleted unnecessary jab>
 
I dunno, when I run on our treadmill at home I don't feel any air moving, that's why I turn that little fan on.........

.........wait a second.....


......is there a fan on this treadmill???
 
Duck_Twacy said:
I dunno, when I run on our treadmill at home I don't feel any air moving
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Airplanes don't run on treadmills like you do. They push air out the back, which propels them forward. It doesn't matter if they happen to be sitting on a moving treadmill when that happens. They have free spinning wheels.
 
[General thread comment]

If there are any more personal jabs taken at anyone's intelligence or genetic make-up, this thread will be shut down. I said in the other treadmill thread, and I'll repeat it here - I don't care if these kind of threads run on for page after page, as long as it remains civil. No poo flinging please.

:bandit:
 
Berkut said:
Airplanes don't run on treadmills like you do. They push air out the back, which propels them forward. It doesn't matter if they happen to be sitting on a moving treadmill when that happens. They have free spinning wheels.
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The treadmill is just moving ground (hence it's purpose, it fits in my office). I use my feet to move across the "ground", the airplane uses it's engine to push or pull the airplane across the "ground". The motion of the treadmill just requires more work to move. If I worked harder than the treadmill, I'd run off the end (or into the front console). But if movement was my goal, I'd just go run out in the street.

This is making my head hurt, I'm gonna watch Lost instead...not that that will be any different....
 
Duck_Twacy said:
The treadmill is just moving ground (hence it's purpose, it fits in my office). I use my feet to move across the "ground", the airplane uses it's engine to push or pull the airplane across the "ground".
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No, it uses its engine to push it through the air. As long as the wheels turn freely, it doesn't matter what the ground does.
 
Duck_Twacy said:
I dunno, when I run on our treadmill at home I don't feel any air moving, that's why I turn that little fan on.........

.........wait a second.....


......is there a fan on this treadmill???
Click to expand...

put on some skates and a jet engine on your back and see if you feel some air. :P
 
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