Will the plane fly?

[Scottwax]

Originally posted by cydewaze
Wow! 9 pages for this!

223 pages before it got moved to the archives on offtopic.com!

[ViperArry]

Wow.... I thought that's an interesting question whilst starting at page one...

But then I saw there are allready 10 pages of replies here.

I didn't read the other replies because there are so many.

My gues is, the plan won't fly.

The plane has to get enough wind underneath the wings to create enough lift to takeoff.

Because it is on a conveyor it will remain at the same place... without creating movement on the runway.
There could be enough speed at wich the plane would normally take off. But because it isn't moving.... it won't get enough air flowing underneath the wings.
Without this air..... the plane will never take off.

But, to be sure, the Mythbusters should indeed test this.

[cydewaze]

Originally posted by ViperArry
Because it is on a conveyor it will remain at the same place... without creating movement on the runway.

The plane will move just fine, since the engine thrust propels it, not the wheels. The only difference between the conveyor and a normal runway is that the conveyor will just make the wheels spin faster.

To do what you're thinking of, you'd need a tailwind that would be equal to the speed of the plane, so that no matter how fast the plane went, there'd be no lift. Or I guess you'd need to anchor the plane in place using some other method, but the conveyor will not stop the plane from moving.

[ViperArry]

Cydewaze,

If the conveyor is running with the same speed as the propellor is thrusting the plane the plane won't be moving forward.

If the conveyor is running at lower speed than thrust..... the plane will move forward.



Lift will be created when the plane moves. Lift won't be created by the propellor, but with the movement due to the propellor.

SO, in my opinion... the plane won't move at all.....

BUT.... the wheels WILL go incredibly fast indeed.....

[SpoiledMan]

You might want to go back and read through the threads. It's been hashed out and shown that ground/wheel speed don't play a part in this. Thrust moves the plane no matter what the ground does.

[ViperArry]

I'll start reading.... this is a very intresting puzzle.

But I don't agree with the last part......

When you are standing on a conveyor belt.....
and you don't run. You'll fall off on the backside.

If you start running.... you'll stay on.

If you can run faster as the belt.... you'll run off it.

Anyway........ I stick to the point that staying in one place doesn't create an air flow on the wings.
Without this airflow there won't be lift.

Now I start reading. Has anyone got a confirmation from the Mythbusters yet?

[rusty bumper]

You can have all the thrust you want, but if you have no airspeed then the plane will not fly.

Many a plane has crashed due to the lack of airspeed.

[Aurora40]

Originally posted by ViperArry
When you are standing on a conveyor belt.....
and you don't run. You'll fall off on the backside.

Planes don't run.

Imagine this. Imagine a small conveyor belt. Imagine you holding a Hot Wheels. If the belt were moving and you hold the Hot Wheel in place on the conveyor, does it matter how fast the conveyor goes? What if it revs up to 2,000 mph? Do you have to counter that with your hand? No because the wheels on a Hot Wheels spin freely. They'll just spin fast.

Now say you want to move the Hot Wheel forward at 5mph. You can do that with your arm, same as if you moved it along the ground. Only the wheels will be spinning more in one case.

A plane is not driven by the wheels, otherwise they'd have problems once they take-off. The speed the wheels move at is irrelevant to the motion of the plane.

If you put an RC car on the conveyor, then you'd have a problem. The RC car is driven by its wheels, so its wheel speed does matter. You'd have to floor the car in order for it to just stay in place, and if the conveyor sped up more than the RC car could drive, it would fly off the back.

[SpoiledMan]

Originally posted by Aurora40
Planes don't run.

Imagine this. Imagine a small conveyor belt. Imagine you holding a Hot Wheels. If the belt were moving and you hold the Hot Wheel in place on the conveyor, does it matter how fast the conveyor goes? What if it revs up to 2,000 mph? Do you have to counter that with your hand? No because the wheels on a Hot Wheels spin freely. They'll just spin fast.

Now say you want to move the Hot Wheel forward at 5mph. You can do that with your arm, same as if you moved it along the ground. Only the wheels will be spinning more in one case.

A plane is not driven by the wheels, otherwise they'd have problems once they take-off. The speed the wheels move at is irrelevant to the motion of the plane.

If you put an RC car on the conveyor, then you'd have a problem. The RC car is driven by its wheels, so its wheel speed does matter. You'd have to floor the car in order for it to just stay in place, and if the conveyor sped up more than the RC car could drive, it would fly off the back.

Bob, this is probably the best explanation that I have heard yet.

[ViperArry]

What ever happened with the logica from LIFT?

True a plane isn´t driven by its wheels.... but without lift it won´t fly.

A plane isn´t a rocket.

Rockets are entirely propelled by a engine.... (booster).
Planes require lift to get up from the ground.

Without movement in a forward motion... creating air underneath the wing.... the plane won´t get in the air.

[teterd]

Originally posted by ViperArry
What ever happened with the logica from LIFT?

True a plane isn´t driven by its wheels.... but without lift it won´t fly.

A plane isn´t a rocket.

Rockets are entirely propelled by a engine.... (booster).
Planes require lift to get up from the ground.

Without movement in a forward motion... creating air underneath the wing.... the plane won´t get in the air.

Who said the plane wasn't moving forward? It has to be moving forward for the belt to be moving at all! The plane is being pulled forward by the plane's engine. When it reaches lift off speed, it will lift off. The engine and plane don't care how fast the wheels are moving as long as they roll!!

[Mosca]

I too thought that the plane wouldn't fly, but this clarified it for me. Unquestionably the plane will fly.

Imagine you're towing the plane by walking along next to the conveyor and pulling the plane with a rope. As you take a step the plane moves with you and the conveyor moves the opposite direction under the tires. You keep walking and pulling the rope and as long as the wheels are free to spin (no brakes or chocks) the plane follows you. The tires have to turn faster because the conveyor is moving under them but the plane still follows you.

[Murr1525]

Wheels spinning in place, and rolling down a runway are too different things.

A plane needs airspeed under its wings, and if it is staying in place, no airspeed. No flight.

And this is the same idea used on a dyno for cars.. put rollers under the wheels and it wont move. Put an airplane on free-rollers, and it wont move either.

[Murr1525]

Sorry Mosca, that changes the whole question. A plane being towed is a different situation than a plane on its own. A fixed length of rope will drag the plane down the converyer belt... but that wasnt the original question.

[ViperArry]

Ok, I read almost five pages now....

people are all saying the same....

When does the conveyor belt start moving? When the plane starts moving.....

Do we agree that air has to flow over and underneath the wings to create enough lift to take off in the air?
I assume we agree.....

So, the conveyor belt starts moving when the plane is moving......
(looks a lot like the riddle... wich was there before the other... the chicken or the egg?)
After the intial movement the conveyor belt will produce exactly the same movement but the other way.

The relative speed compared to the point you are viewing it... (because you want to know what happens)is 0. This is just Newtons laws..... Action = Reaction.....

Without moving from the position you are standing..... the plane won´t takeoff.


BUT, when an airstream is introduced.......... it will be able to takeoff. But how IS this airstream going to be produced when the plane isn´t moving.

I read people are saying..... the turbines get the air flowing on the wings...... How is this going to work? The turbine is hanging UNDERNEATH the wing.... so it won´t create the air flow over the wing..... only the tail gets the airflow.... but the tailwings are too small to get enough lift to lift the entire plane.

I read......
The F16 has the engine on the rear.... so how is this going to get air flowing underneath the wings?



When someone gets to explain that air will flow (in sufficient speed) underneath the wings...... he or she will have the problem solved... and the plane will fly.
Without airflow, the plane will fly like a brick simply NOT.

Then again.... reading the last answers.... If the plane will get to move, it will fly.... but..... this towing thing wasn´t in the original riddle.
It doens´t matter how fast the engines turn... the wheels just keep spinning faster and faster.... but without the needed amount of lift, the plane won´t fly.

I stick to this.