Mythbusters, Plane on a treadmill..

[ImbracableCrunk]

Can someone please post the original Coopervane question/scenario? There has got to be a good reason why this isn't obvious to everybody.

From the man, the myth, the legend, CooperVane himself:

Let's say you had a giant treadmill with an airplane on it
I thought I would dust off this old gem to kill the PIC thread.

Let's say you had a giant treadmill with an airplane on it.

As you add power and begin to move for the takoff roll, the treadmill speeds up and keeps the plane in the same relative position. As the plane goes faster, the treadmill speeds up, always maintaining the aircraft's relative position.

Would you ever be able to take off?

GO!!
_____________

 

[PCL_128]

Coopervane rewrote the original question in an incorrect manner. The original internet sensation question never states that the airplane remains in the same relative position. It merely states that the treadmill spins in reverse at the same speed as the airplane's wheels. Despite this, people have still been arguing that the plane can't take off for a couple of years now. The problem really isn't Coopervane's question (although it was rewritten incorrectly), the problem is that people don't understand basic physics.

 

[pbruk]

For those of you dis'n Andy Neill, he is an Army warrior who can easily take any of you blindfolded. You should consider who you're messing with before striking the keys. Andy, hope all is well at OO.

Here's another you tube treadmill: http://www.youtube.com/watch?v=-EopVDgSPAk&NR=1

 

[Herman Bloom]

For those of you dis'n Andy Neill, he is an Army warrior who can easily take any of you blindfolded. You should consider who you're messing with before striking the keys. Andy, hope all is well at OO.

Here's another you tube treadmill: http://www.youtube.com/watch?v=-EopVDgSPAk&NR=1

Unfortunately that won't make him any smarter.

 

[JimNtexas]

For those of you dis'n Andy Neill, he is an Army warrior who can easily take any of you blindfolded. You should consider who you're messing with before striking the keys.

I'm sure Andy is a fine man, but his actions in the physical world are governed by Sir Isaac Newton's laws of motion, just like the plane on the treadmill.

 

[Caveman]

I couldn't bear to read this whole thread so I skipped to the end. Forgive me if this has already been posted. The treadmill is a distractor. How fast the wheels are spinning is irrelevant. How fast the treadmill is moving is irrelevant. OTOH, how long the treadmill is is extremely important.

If the aircraft doesn't accelerate in relationship to it's surroundings it isn't going to fly. Period. Forget the treadmill belt. It can spin as fast or as slow as you want. Unless the aircraft accelerates relative to it's fixed surroundings it ain't gonna fly. Imagine the belt spinning and the a/c has just enough thrust to offset the tire/belt/wheel bearing friction, probably barely above idle. So, there we are. A small amount of thrust, the belt is moving one way, the wheels are spinning the other way and the airplane is MOTIONLESS. Therefore, no airflow, no flight. Add some more thrust and the a/c starts to accelerate down the runway (treadmill). Now you have airflow over the wings. Get going fast enough before you run out of runway (treadmill) and you will fly. How fast the wheels are spinning or how fast the belt is moving has nothing to do with it.

Some of you are trying to picture a MOTIONLESS aircraft at full thrust sitting on a spinning treadmill and then somehow it magically levitates and flys away. Never gonna happen. The a/c still must accelerate down the runway (treadmill) and create some airflow in order to get airborne. The guys that say it will fly aren't telling you that you need a really long treadmill to make this work. They are letting you imagine a treadmill barely the size of the a/c and you keep 'seeing' an airplane that suddenly just lifts off and flys away. In the case of the ultralight on the show it needed about 100' of runway (treadmill) to demonstrate how it works. If the demonstration was done on a 25 foot traditional looking treadmill, the demonstration would have failed. With or without a treadmill, the ultralight still needs about 100' to take off. The only difference is that a tiny additional amount of thrust was needed to offset the friction from the tarp moving under the wheels.

I saw the Mythbusters episode. IMO, they did a lousy job of explaining how, what, when and why the airplane flew. They just demonstrated that it would fly and acted amazed. It isn't amazing. It's basic physics and Aviation 101.

 

[JimNtexas]

deleted because I misread the prior post.

 

[ASA_Aviator]

I couldn't bear to read this whole thread so I skipped to the end. Forgive me if this has already been posted. The treadmill is a distractor. How fast the wheels are spinning is irrelevant. How fast the treadmill is moving is irrelevant. OTOH, how long the treadmill is is extremely important.

If the aircraft doesn't accelerate in relationship to it's surroundings it isn't going to fly. Period. Forget the treadmill belt. It can spin as fast or as slow as you want. Unless the aircraft accelerates relative to it's fixed surroundings it ain't gonna fly. Imagine the belt spinning and the a/c has just enough thrust to offset the tire/belt/wheel bearing friction, probably barely above idle. So, there we are. A small amount of thrust, the belt is moving one way, the wheels are spinning the other way and the airplane is MOTIONLESS. Therefore, no airflow, no flight. Add some more thrust and the a/c starts to accelerate down the runway (treadmill). Now you have airflow over the wings. Get going fast enough before you run out of runway (treadmill) and you will fly. How fast the wheels are spinning or how fast the belt is moving has nothing to do with it.

Some of you are trying to picture a MOTIONLESS aircraft at full thrust sitting on a spinning treadmill and then somehow it magically levitates and flys away. Never gonna happen. The a/c still must accelerate down the runway (treadmill) and create some airflow in order to get airborne. The guys that say it will fly aren't telling you that you need a really long treadmill to make this work. They are letting you imagine a treadmill barely the size of the a/c and you keep 'seeing' an airplane that suddenly just lifts off and flys away. In the case of the ultralight on the show it needed about 100' of runway (treadmill) to demonstrate how it works. If the demonstration was done on a 25 foot traditional looking treadmill, the demonstration would have failed. With or without a treadmill, the ultralight still needs about 100' to take off. The only difference is that a tiny additional amount of thrust was needed to offset the friction from the tarp moving under the wheels.

I saw the Mythbusters episode. IMO, they did a lousy job of explaining how, what, when and why the airplane flew. They just demonstrated that it would fly and acted amazed. It isn't amazing. It's basic physics and Aviation 101.

I didn't think that the plane would "levitate" off of the treadmill. I have always said that it would take off just like normal. The wheel rotation speed would be equal to the groundspeed PLUS whatever speed the treadmill is moving. So, if it normally rotates at 140 knots, and the treadmill is going 100 knots, then the wheel speed would be 240 knots. The airspeed will be the same as always though, 140 knots.

The point is taken though, the treadmill is irrelevant. The plane departs the "runway" whether it is a treadmill or a runway.

 

[dash8driver]

the only person amazed on the mythbuster show was that ultralight pilot. it was pretty obvious that the "amazement" shown by the hosts were sarcastic.

 

[COOPERVANE]

I've already stated that my question was worded differently and INCORRECTLY from the original question.

It was meant to be a light hearted discussion to stop a stupid thread about logging PIC in the right seat. I wish I hadn't brought it up.

It should have been written either:

A:"the treadmill is DESIGNED to keep the airplane stationary"

or

B:"As the airplane adds power, it ATTEMPTS to keep the airplane in a relative position"

Can we go back to arguing with 1000 hour wonders logging PIC in the right seat?