Will the plane fly?

[smokinwrench]

This has been argued forever. If a plane is on a free folling conveyer belt will it take off?

We will get our answer Wednesday 9pm E. Myth Busters are going to tackle this myth.

[ATC-Eric]

I say no, but am excited about the experiment.


Sorry to hear about you foot homeboy. It sucks to be doing something so mundane and simple when you break it. A cool story would have made things a little better

[TwoHundredEx]

[Billy Golightly]

I think the original question is something to the effect of, a plane is setting on a conveyor belt, as the plane speeds up so does the conveyor belt matching its speed in the opposite direction, can it take off?


So I ask myself, self, if I have an air boat in the middle of the river, does it take more throttle to go upstream, then down stream? and the answer is yes, it does. Now what happened if the stream was powerful enough that it was constantly increasing in speed as I tried to go up it? I think I'd have a hard time going anywhere.

[RedRider_AK]

I like TwoHundredEx's take on this matter.

[Dammit!]

The plane takes off!!!

[SYKO]

my answer is scientific and fact oreinted....








































I dont give a damn......

[SWIGIN]

you need air movement over the wings for lift...... if the engines are just keeping it on the tread mill, its sitting still and the wings get no lift

[69HemiGTX]

Actually, the scenario depicted by TwoHundredEX is both correct and incorrect at the same time. The only way the conveyor will move in the opposite direction is if the wheels produce a rotational moment. This is assuming the conveyor is unpowered. Newton's Third Law of Motion: For every action, there is an equal and opposite reaction. The only appreciable force is applied to the airframe of the plane, which causes the plane to move forward. If the wheels provided a rotational moment, the belt would react by moving in the opposite direction. The wheels of an airplane are not driven by any force, therefore, they cannot deliver any rotational force to the surface below them. Rolling resistance is the only force seen between the wheel and ground. This rolling resistance, in a perfect scenario, would actually cause the belt to move in the same direction as the airplane, but at a slower rate due to the difference in friction between the belt and the conveyor and the airplane and the air. Confused yet?

Do this experiment if you can. Find a conveyor with rollers instead of a rubber belt. The rollers make it much easier to do this because you won't be able to produce enough force manually to overcome the friction of a rubber belt. Take a bicycle and roll it across the conveyor, increasing speed with distance traveled, without using the pedals. This simulates the force the engines inflict on the plane and its resultant acceleration. Remember, no force goes to the wheels. Guess what? The rollers will roll in the same direction as the bike, but at a slower rate. Amazing, huh?

Now what Billy is talking about actually would happen. If an airplane is on a conveyor belt that can accelerate fast enough to keep the airplane relatively still, the airplane will not take off, no matter how much throttle is applied. The thing to remember here is that the belt is powered by an outside source and is not driven by the airplane. Airplanes only take off when the relative wind across their wings is enough to produce a resultant lift greater than the weight of the airplane. If the airplane doesn't move fast enough relative to the air it is passing through, the wings will never produce the force necessary for flight. The wheels might be spinning at 100 knots, but if the wings are only moving 5 knots and the minimum takeoff speed (V1) is 75, the plane will not leave the ground.

Now are you confused?

[TwoHundredEx]

Now are you confused?

More than you can imagine.....

[69HemiGTX]

More than you can imagine.....

Mission accomplished.

[SPD FRK]

Now are you confused?

Not even a little. Although BG's explanation was easier to comprehend.
Plane ain't goin' nowhere until either it moves fast enough through the air or the air moves fast enough past the plane.
Are there really people who need this proved to them? Pity.

[The Goat]

am I the only one who sees the problem when they try to turn the belt off...or cut power to the engines? the plane is gonna go one way or the other, cause enither wil be able to be turned off at the exact instant.

I can see the headlines now.

[Brockey]

I cant see it flying. I figures the plane will just slowly drive off the conveyor. The wheels dont turn, the engine propels the plane and air flow under the belly and wings make it lift. So in my mind it isnt going anywhere. Now if that could generate enough airflow to point under the plane would it fly?, answer still is no. It would lift and not go forward. It needs the thrust forward with airflow under the plane. Nevertheless I will watch mythbusters as I love the show. Just my .02 cents.

[Yamada]

The plane take off!