This is highly controversial debate that's still raging I think. And I've edited some details to make it clear of the scenario. It is reflected in bold text

The question is that can a plane take off on a conveyor belt moving at the same speed in opposite direction?

In simple form - Can a plane take off while being stationary? Having it's forward rolling momentum elliminated?

Both camp of yes and no are split quite evenly.

The 'Yes' camp argued that :

- Plane do not use wheels to fly, so it can lift off even if the ground is moving away at the opposite direction at the same speed.

The 'No' camp argued that :

- If the plane remained stationary, it wouldn't have forward momentum for air to slice through to the wing to generate lift, hence it won't have lift off.

Sure, Mythbuster tested the myth, but through proper observation you will notice that both model and full scale plane in the myth has some forward momentum.

In my opinion, not definite fact, there's flaws in this debate.

- Propeller propelled air into the wing, thus able to generate lift despite being stationary.
- If plane are able to lift up without moving, why does it still need a runway? VTOL would be laughing stock since it's an invention that fixes nothing!

So IMO, a plane on a conveyor belt wouldn't fly away. I am on the 'No' camp

This post has been edited by wKkaY: Jun 20 2009, 03:33 PM

Uhh, I don't think you have the setup right

The conveyor belt is moving away in a way that it's making the plane stationary.

Yeap, I meant the latter, the conveyor belt moves away at the same speed at every condition. Meaning the plane is always stationary.

Kite would fly IF you yanked on the string, providing movement for the kite through the air. It's the same why kite fly when it's high up even if you're standing still because there's enough gale in the atmosphere to keep it flying.

So far everybody saying no, I don't believe it's possible to fly either but anyone who's a fan of Mythbuster will notice that their plane took off on a conveyor belt so... explanation?

They did a control test to determine the minimum take off speed of the plane and it's shown that the car can match that speed.

I am not very convinced because I do noticed some forward momentum in the plane. I really hate to prove them wrong because I am a big fan of them but in truth I still don't see how a plane can fly while remaining stationary.

Another possible explanation is the plane design itself. The air pushed by the propeller actually passing through the wing, and there's enough lift to lift the wheel away from the conveyor belt, allowing it to accelerate forward and fly off.

This post has been edited by SeaGates: Jun 16 2009, 06:54 PM

Ok ok, when you mentioned regardless of what the conveyor belt is doing. I think you still mistunderstand the concept of the conveyor belt here.

The conveyor belt is moving at a constant speed to match the forward speed of the aircraft so the aircraft is effectively stationary. The conveyor belt accelerate at the same rate as the engine would accelerate the aircraft. Effectively canceling it's forward rolling speed.

Elliminating the conveyor belt, and let's say use an alternative method to keep the aircraft stationary at the same spot- wheel brakes.

Will the aircraft lift off?

There's another clip that support the 'no' camp argument. By, guess who? The one that busted the myth themselves.



Problem with this argument is, not all the aeronautics experts are in the same camp. Asking several engineer from Airbus/ Boeing / Bombardier/ Embraer may yield different answer. So far the debate carried on because experts in this field are yet to come together to give a definite answer.

Ok I've edited first post to reflect the purpose of the conveyor belt and clarity of the quesiton. There are other better method to keep a plane stationary I guess

Jet aircraft would be the worst type of aircraft to demonstrate this problem.

Somehow I realize this debate would not exist if somebody say 'Hey! Conveyor belt is the worse method of keeping a plane stationary'

After reading for a while, I think I am switching camp

The explanation given is that, the conveyor only apply force to the wheel, and since the wheel is free rolling, the force doesn't transfer to the plane, so it won't be affecting the plane.

If conveyor belt is moving back at A speed, and plane have a forward trust of B speed. The only difference is that the wheel will be moving at A+B speed while the plane move forward at B speed.

Even if the conveyor belt is moving to match the forward trust of the plane. It simply means the wheel move at 2xB speed while the plane moves at B speed.

So on a infinitely long conveyor belt. The plane will still treat it as if it's a static tarmac and take off after gaining enough forward movement to achieve take off speed.

Reason wheel brakes can keep a plane on the ground is that the brake pads is the transfer medium for the force on the wheel to the aircraft.

Did I get it right?