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Will the plane take off?

poet_x

poet_x

Experienced Member
Joined
30 April 2003
Messages
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Location
Indianapolis, IN
Ok, by now we have all heard the question about a plane on a treadmill. I just wanted to let you guys know that tonight, Mythbusters will try to solve the riddle (though the intelligent people out there I think already know the answer). It's on at 9:00pm est. Just a heads-up...

:biggrin:
 
holy crap! From the title I thought you started another thread on the topic!!! :eek: :eek: :eek: I saw the title and thought... "NOOOOOOOOOOOOOOOO" :tongue: :tongue:

Good to hear though. I don't watch that show much, but I'll be sure to catch it (along with the WEC match-ups tonight!!!).

Bob
 
I tivo every episode of Mythbusters. Oddly enough, my friend and I debunked this myth with an R/C airplane. It was a prop driven plane but that shouldn't matter. The little plane had no trouble moving right along the treadmill no matter how fast the it (treadmill) was set to run. The plane didn't seem to take into account how fast the treadmill was moving, it looked strange but it moved as if the treadmill wasn't even there. I am sure the show will produce the same results. We held/stopped the plane from moving backwards on the treadmill while it (treadmill) was moving at full speed, then applied power to the plane and it moved forward as if it were on pavement. Granted it didn't take off but that shouldn't matter in this case.
 
ALSWEL said:
I tivo every episode of Mythbusters. Oddly enough, my friend and I debunked this myth with an R/C airplane. It was a prop driven plane but that shouldn't matter. The little plane had no trouble moving right along the treadmill no matter how fast the it (treadmill) was set to run. The plane didn't seem to take into account how fast the treadmill was moving, it looked strange but it moved as if the treadmill wasn't even there. I am sure the show will produce the same results. We held/stopped the plane from moving backwards on the treadmill while it (treadmill) was moving at full speed, then applied power to the plane and it moved forward as if it were on pavement. Granted it didn't take off but that shouldn't matter in this case.
Click to expand...
The difference is in the scale. I'm sure you noticed that as the treadmill moved faster the plane moved forward more slowly. That's due to the friction in the wheels. Not a big deal when you're talking about a 10mph difference. But when you ask wheels designed to spin 180mph to spin 360mph that friction could very well become unmanageable.

We'll see tonight. :)
 
dave22 said:
The difference is in the scale. I'm sure you noticed that as the treadmill moved faster the plane moved forward more slowly. That's due to the friction in the wheels. Not a big deal when you're talking about a 10mph difference. But when you ask wheels designed to spin 180mph to spin 360mph that friction could very well become unmanageable.

We'll see tonight. :)
Click to expand...

I see what your saying however, it didn't matter how much power was added to the plane. It still moved forward when the treadmill was a full speed. A little power got it moving slowly and a lot made it hit the controll stand legs instantly just like if it were on pavement. Friction may make a difference in reality but I dont believe friction at the wheels is whats in question here.
 
Well, well, well, I was just discussing this being on mythbusters tonight with a freind down here in Florida and he says...so what's the myth? Makes good sense to me. Where is the myth in this?

Defination of a myth...

http://www.m-w.com/dictionary/myth

People seem to be pretty much 50-50 on this thing so how is it a myth.
 
steveny said:
Well, well, well, I was just discussing this being on mythbusters tonight with a freind down here in Florida and he says...so what's the myth? Makes good sense to me. Where is the myth in this?

Defination of a myth...

http://www.m-w.com/dictionary/myth

People seem to be pretty much 50-50 on this thing so how is it a myth.
Click to expand...


(I'm sure they understand it's more of a debate than a myth. :wink: )

I can't believe we're even having this discussion again.... :rolleyes:

Physics says it will fly. Logic says it will fly. Nature says it will fly. The God Damn thing will FLY!!!!!!!!!!! :mad: :mad: :mad: :mad: :mad: :mad:
 
It'll fly...every time guys. lol

(the best way to think about it is how you can "hold the plane in place" while the treadmill speeds up....DO YOU HAVE THE HOLD THE PLANE WITH ANYMORE FORCE AS THE TREADMILL SPEEDS UP TO KEEP IT IN PLACE?? Nope...and thus, as you add thrust with the propeller, the plane will move forward and take off, no matter how fast the treadmill is moving in the opposite direction...I don't care if it's moving light speed.)

Another analogy: You are walking thru the airport while pulling your luggage along behind you...you know, the type with the little wheels? You come across a motorized airport walkway going the opposite direction, and place your bag on it so that the wheels are spinning but instead of walking down the walkway, you walk along side of it. Is it harder to walk forward with the walkway spinning in the opposite direction of the way you're walking, or is it the same as if it was on the floor? The spinning of the wheels negates all force (except minute friction) that pulls on your arm.
 
dave22 said:
The difference is in the scale. I'm sure you noticed that as the treadmill moved faster the plane moved forward more slowly. That's due to the friction in the wheels. Not a big deal when you're talking about a 10mph difference. But when you ask wheels designed to spin 180mph to spin 360mph that friction could very well become unmanageable.

We'll see tonight. :)
Click to expand...

Friction is independent of velocity. The friction imparted by the wheel is the same at 1 mph as it is at 1,000,000 mph. The equation for rolling resistance (aka friction from a rotating wheel) is:

F(r) = Crr * N

F(r) = Rolling Resistance Force
Crr = Coefficient of Rolling Resistance
N = Normal Force (Force = mass * acceleration (aka gravity))

Assuming the wheel can handle the centrifugal forces, the amount of rolling resistance is a constant value at any speed.
 
steveny said:
Thats where my money would be, if the plane is actually moving the same speed as the treadmill is moving. We shall see tonight.
Click to expand...

This would be true if this was a car on a treadmill because the forces actually used to move the car are generated at the wheels. However, a plane is not a car. The forces used to move the plane are generated at the turbines and "push" the plane forward, while the wheels spin freely. It would be an incorrect assumption that the plane's movement have anything to do with the rotational speed of the wheels. The plane can still move forward even if its wheels were moving backwards.
 
DrVolkl said:
It'll fly...every time guys. lol

(the best way to think about it is how you can "hold the plane in place" while the treadmill speeds up....DO YOU HAVE THE HOLD THE PLANE WITH ANYMORE FORCE AS THE TREADMILL SPEEDS UP TO KEEP IT IN PLACE?? Nope...and thus, as you add thrust with the propeller, the plane will move forward and take off, no matter how fast the treadmill is moving in the opposite direction...I don't care if it's moving light speed.)

Another analogy: You are walking thru the airport while pulling your luggage along behind you...you know, the type with the little wheels? You come across a motorized airport walkway going the opposite direction, and place your bag on it so that the wheels are spinning but instead of walking down the walkway, you walk along side of it. Is it harder to walk forward with the walkway spinning in the opposite direction of the way you're walking, or is it the same as if it was on the floor? The spinning of the wheels negates all force (except minute friction) that pulls on your arm.
Click to expand...

Yup, great analogy.

I don't know why it's so hard for people to understand that a free spinning wheel imparts no forces in the direction of travel. I think a lot of controversy would be eliminated if the question was posed as a plane on its belly but with a near frictionless grease between the plane and the treadmill; which essentially is the equivalent scenario.
 
Strap a handglider on your back and a pair of roller blades on your feet , crank up the treadmill and see how high you go........................................................................ NOT.
BORAT.jpg



Armando
 
Cool, an airplane hour. gonna have to watch it.

I want to see how the measure the wheel speed and conduct the experiment. IF they do it according to the way its worded it won't go anywhere.

And they better account for prop-wash. I've seen R/C planes take off with almost just that.
 
steveny said:
That is a really good point. I wonder how they are going to word it? That makes all the difference.
Click to expand...

from another site I frequent

Airplane Hour
(Weds., December 12 at 9 PM ET/PT)
Adam and Jamie find out if either of them can safely land a Boeing 747-400 on a runway in varying weather conditions. Meanwhile, Kari, Tory and Grant risk life and limb to investigate skydiving myths regularly featured in Hollywood action films. Is it possible to catch up with someone in freefall if that person jumps out a plane before you do? Can you really hold a conversation during freefall? And would you survive if you opened your parachute only a few feet off the ground? Finally, Adam and Jamie carefully navigate their way through a myth that has baffled everyone from web bloggers to pilots. If a plane is traveling at takeoff speed on a conveyor belt, and the belt is matching that speed in the opposite direction, can the plane take off? Extensive small-scale testing with a super treadmill and a nearly uncontrollable model airplane don't completely resolve the myth, so our flight cadets supersize the myth with help from a willing pilot and his Ultralight flying machine.
Click to expand...
 
If enough air moves under the wings, it will fly. I think most people agree if the plane doesn't move forward, it will not fly.

The argument most of people who say it will fly have is that the plane will move forward regardless, simply because the thrust will overcome the friction of the wheels.

I think if the plane can be held in the same position with its thrusters going full blast, it will not fly. Most of the arguments I read for the plane flying are that it is impossible to keep the plane from moving forward. I think however at some point if the treadmill were fast enough that it would be able to keep the plane from moving forward. The interpretation of the "treadmill matching the speed of the plane" is what may decide this.

I also am not sure that there is enough data in the puzzle to come up with a conclusive answer. What kind of a jet is it? How much does it weigh? How much thrust do the engines have. Assumptions will have to be made.

I think the Mythbusters have done a pretty good job at confirming or busting these myths. However, I think this argument will not be over even after this show airs and they confirm or bust. Thanks for posting the info on the show, I'm really looking forward to it. This is better than MMA. :)
 

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