Mythbusters - airplane on a conveyor belt

I don't think this will necessarily end the controversy though. Towards the end of the "Harmless riddle" thread, the "No it won't" side was using a hypothetical treadmill with infinite acceleration. I doubt even "Mythbusters" can test that one.

Why is this still such a controversy? Everyone with a brain has concluded that it's the engines that cause a plane to take off. The wheels will basically be spinning freely, and it won't matter what speed they're going. The plane takes off.

kari byron ftw

The engine will cause it to take off....but once it leaves the belt will it remain in the air without the air producing the lift? Highly doubtful. The airplane will crash and burn and it will be ugly...:)

Alan

This whole airplane on a conveyor belt thing baffles me. I mean, if it was done in a wind tunnel than I would that the plane could definetly take off. But outdoors? How in the hell could the plane take off without air passing rapidly over the wings?

maybe that big of a conveyor belt will (due to friction) move a whole bunch of air over the wings

hyman shoulder wrote:

Why is this still such a controversy? Everyone with a brain has concluded that it's the engines that cause a plane to take off. The wheels will basically be spinning freely, and it won't matter what speed they're going. The plane takes off.

I have a brain.

It is not the engine that makes a plane take off, it's the physical reaction of the wings moving through air that generates lift.

i kinda like running wrote:

But outdoors? How in the hell could the plane take off without air passing rapidly over the wings?

The people who say it will take off say this:

Air DOES rapidly pass over the wings, creating lift, because the plane moves forward on the treadmill. How? Well, a car moves forward because the wheels are connected to an axle that is connected to the engine. It's the friction between the tires and the road that make the car go forward. The tires push off the road.

If you removed the road, and just suspended the car on string, the tires would rotate but the car would remain motionless.

They argue that a plane is different. The airplane doesn't move based on the tires pushing off the road. It's the engines that push it. The engines are only "connected" to the air. If you remove the runway and suspended a plane on a string, it will still thrust forward.

The wheels on a plane are basically free rotating, like a skateboard or rollerskate. There is some friction but not much. If you start the treadmill with the engines off, the plane will move backward, but as soon as the engines go on, it will move forward and overcome what little friction exists between the plane and freely rotating wheel.

That's what people who say the plane will take off say. But you already knew that of course, because you are a troll looking to keep the argument going and I just fed the troll. Oh well.

not kilgore wrote:

I have a brain.

Not much of one.

Do people really think jet engines pull air over the wings and that's what generates the lift? If this was the case all planes could take off as soon as their engines reached operating RPM. Engines take some air in, but discharge that air with a much higher force which by Newton's third law cause the plane to move forward. If it's on a treadmill, the plane won't move forward, air won't go over the wings, and the plane won't lift off the ground.

The more I think about it, the more I think that the ultralight will take off. In the thought experiment, no, but I do think that the conveyor belt will move so much air that the ultralight, which has a very low stall speed, will take off.

M. Allen wrote:

Engines take some air in, but discharge that air with a much higher force which by Newton's third law cause the plane to move forward.

You say this, which is exactly correct, you think the spinning little wheels touching the treadmill will somehow counteract this propulsive burst of air? Please explain.

No. I'm not a troll. I was just genuinely curious.

I'm just gonna have to see this thing happen myself.

The only way this plane will take off is in a headwind strong enough to lift it, with its engines running hard enough to pull the plane through the headwind. End of discussion jackasses

two relevant points that I don't think anyone has mentioned yet:

1. Airplanes can only generate lift when air is moving rapidly over the surface of their wings.

2. Teg does not run the 10k

So you really think that the treadmill is going to keep it still? You're a moron.

t r o l l i n g. :)

phstenning wrote:

So you really think that the treadmill is going to keep it still? You're a moron.

no it won't keep it still. but...this plane can take off in a quarter mile runway/treadmill?

The engine pushes the air, the plane goes forward, it runs off the treadmill, when the air is moving fast enough to create lift that exceeds the planes weight, the plane gets off the ground. Unless the brakes are on, all the treadmill does is make the wheels spin faster.