Will the plane fly?

[SVT Lightning]

Originally posted by 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.

But all you have to do is substitute prop or jet thrust for the rope. Doesn't matter what is propelling the plane.....whether it is being pulled or pushed.....it will still move forward.

[ViperArry]

But SVT... the conveyor belt is moving with the exact same speed......

So the plane won´t be moving from you... does it?

The same goes with this:

Your car is on the dyno....... the car is propelled by a rocket.
If you put your hand outside the window.... will there no wind.

Imagine this.......

You´ll jump in the air.
Why doesn´t the earth turn from you.......... so you won´t be in another place when you land.
The earth is moving in the exact same speed as you are doing....

[Aurora40]

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.

The plane will have lift. It will move forward, irrespective of which direction or speed the wheels and conveyor are turning.

Imagine this: you have a plane, it moves forwards by thrust. The wheels could be ice skates or skis instead, but the plane can still take off, right? All that matters is the thrust moves the plane forwards. The only part that matters in relation to the contact with the ground is do they drag at all. Wheels that roll freely won't drag much at all. So no matter what they or the conveyor are doing, the plane will move forwards.

Unless you feel the drag from wheels is significant, then it's utterly irrelevant what they are doing.

Actually, imagine this: The conveyor belt is covered with oil, and the plane has skis. The oil is so slick, that you can turn the conveyor on to 200mph, and hold that huge plane in place with your hand. Now what happens when the plane punches it? It would move forward, right? With the skis sliding effortlessly over the conveyor belt. Now substitute wheels in for oily skis and you've got it.

[Aurora40]

Originally posted by ViperArry
Your car is on the dyno....... the car is propelled by a rocket.
If you put your hand outside the window.... will there no wind.

Put your car so that the wheels sit helplessly on free-spinning dyno wheels. Then fire up a rocket and I guarantee you'll feel a breeze. That car will shoot off those dyno wheels, through the wall of they dyno facility, and down whatever field is behind the place!

If not convinced, then what do you feel would happen? Say the car had no engine and no tranny, but the wheels were there basically in neutral. When you fire the rocket up, what do you think would happen? Would the wheels just spin in the dyno drums faster and faster as the rocket burns, but the car goes nowhere? How would the rocket cause the wheels to spin? They dyno drums are free-rolling. That doesn't really make sense when you lay it out like that.

Originally posted by ViperArry
You´ll jump in the air.
Why doesn´t the earth turn from you.......... so you won´t be in another place when you land.
The earth is moving in the exact same speed as you are doing....

You are turning, the same as the earth is, the same as the air around you is. Jumping doesn't stop your rotation. There's no real comparison to a jet taking off here.

In fact, this would disprove your theory on the plane rather than prove it. Imagine the earth is the big conveyor. It is moving really fast. So planes that try to take off east-to-west wouldn't be able to, right? They'd punch up the jets, but the earth turning under them would prevent them from moving. The same as a plane trying to take off going the opposite direction as the conveyor belt.

In order to take off, all planes would have to go west-to-east, the same as going the same direction as the conveyor belt.

This is obviously not true in reality, just as it isn't true in your explanation of the conveyor result.

[SVT Lightning]

Originally posted by Aurora40
In fact, this would disprove your theory on the plane rather than prove it. Imagine the earth is the big conveyor. It is moving really fast. So planes that try to take off east-to-west wouldn't be able to, right? They'd punch up the jets, but the earth turning under them would prevent them from moving. The same as a plane trying to take off going the opposite direction as the conveyor belt.

In order to take off, all planes would have to go west-to-east, the same as going the same direction as the conveyor belt.

BRILLIANT!!!!!!!!

[Mosca]

Originally posted by 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.

It is 100% analogous, though. Substitute the propeller moving against the air for the force generated by pulling the rope. To say that because the conveyor is turning the plane can't move over top of it is wrong, because the rope analogy shows one instance of that actually happening. The force is separate from the movement over the conveyor. The wheels aren't moving the conveyor, and the plane isn't moving relative to the conveyor; it is moving relative to the earth.

What really happens is that the plane moves forward at 20mph, the conveyor turns backwards at 20mph, and the wheels turn at 40mph to make up the difference as the plane 's propeller pulls it forward.

[rusty bumper]

I still don't see the plane flying.

The only way the plane will fly is for it to have enough lift to break contact with the conveyor belt. The plane's thrust is cancelled out by the equal opposite movement of the conveyor belt, so all we get is spinning wheels.

The plane would need a second (vertical) force to provide lift since it can't get any airspeed.

If it is true that a plane can take off with no forward movement, then I'm sure the Navy would have already had this kind of system in place to launch it's planes off of aircraft carriers.

Currently, only helicopters or Harrier Jump Jets have this means of liftoff.....that I know of.

[black240sx]

One more time:

The planes wheels are free-wheeling. The brakes are not applied and the wheels are not driven by the engines.

The conveyor belt can go backwards at whatever speed it wants, but cannot stop the plane from being pushed forward by it's propellers/jets.

The plane will move forward and take off once it reaches sufficient air speed. The conveyor belt is a red herring.

[Desertdawg]

I wonder if we are going to have to re-hash this about every 2 weeks when someone new finds this thread???

Maybe we need to put on the very first post that you can't reply until you have read the entire thread.

[rusty bumper]

Originally posted by black240sx
The plane will move forward and take off once it reaches sufficient air speed. The conveyor belt is a red herring.

But that's just it.....The plane can't get any air speed because the conveyor is matching the plane's thrust.

The only way the plane will move forward is for it to become airborne.

[rusty bumper]

Originally posted by Desertdawg
I wonder if we are going to have to re-hash this about every 2 weeks when someone new finds this thread???

Maybe we need to put on the very first post that you can't reply until you have read the entire thread.

I agree.

It took me a while to read the whole thread.

[the other pc]

Originally posted by Desertdawg
I wonder if we are going to have to re-hash this about every 2 weeks when someone new finds this thread??? ...

That must be how it got up to 223 pages on offtopic.com. Anyone who doesn’t read the detailed discussion from earlier is doomed to rehash the same arguments over and over and over again.


PC

[Desertdawg]

Originally posted by Rusty Bumper
But that's just it.....The plane can't get any air speed because the conveyor is matching the plane's thrust.
The only way the plane will move forward is for it to become airborne.

Ok, think of it this way, if the plane moves forward at 1 mph then the belt moves at 1 mph the opposite direction. if this was to bring the plane to a stop, then wouldn't the belt stop also???

BUT, since the prop or thrust is increasing, the plane would move faster, and so would the belt, would the plane stop? NO!
It would continue to gain speed.

The prop moves the plane, not the wheels, they are just coasting.... It doesn't matter if they coast at 5 mph or 500 mph, the prop is still pulling the plane forward....just like the rope.

[ViperArry]

I tried to explain it with the world for example... but I couldn't

This thing keeps up in my mind all the time......

I thougt about it this morning driving to work.

If not convinced, then what do you feel would happen? Say the car had no engine and no tranny, but the wheels were there basically in neutral. When you fire the rocket up, what do you think would happen? Would the wheels just spin in the dyno drums faster and faster as the rocket burns, but the car goes nowhere? How would the rocket cause the wheels to spin? They dyno drums are free-rolling. That doesn't really make sense when you lay it out like that.

This is exactly what I thought.....
The rocket will burn..... creating a forward moving force.
But, the conveyor belt will move exactly the other way... with the same force......

The rocket will begin to get more and more power....
But unless the wheels are free from the ground, thus the conveyor belt, there won't be a movement from the starting position.

When the contact with the ground is lost... the conveyor belt will stop holding the object to its place.....
But, the contact with the ground won't be lost untill the object gets enough movement to get air flowing underneath the wings... creating lift.

This:

Put your car so that the wheels sit helplessly on free-spinning dyno wheels. Then fire up a rocket and I guarantee you'll feel a breeze. That car will shoot off those dyno wheels, through the wall of they dyno facility, and down whatever field is behind the place!

Isn't true.... how is the rocket going to get you off this dyno wheels?

What is the basic princible of dyno runs..... and this conveyor belt thing.
Any object moving (propelled by whatever....) won't move UNLESS there is a 3th force outside it.
A mule in front of the plane... with a rope is the only thing capable to move the plane OFF this conveyor.

If the plane won't get off the conveyor... there won't be movement at all... just fireworks and a lot jet blast.
Without movement, no airstream.... no airstream no lift, it's as simple as that.

SO, unless you insert this mule thing...... OUTSIDE the construction there won't be movement at all.....
(The proppellor is on the construction.... this is like a mule walking on the conveyor belt.... trying to pull the plane with a rope...... movement is equal to 0.)

[Mosca]

Originally posted by Rusty Bumper
But that's just it.....The plane can't get any air speed because the conveyor is matching the plane's thrust.

Ah, but it is not, and that is the catch. It is matching the plane's airspeed, not its thrust. The plane moves forward at 20 miles an hour, the conveyor moves backwards at 20 miles an hour, and the wheels move at 40 miles an hour to offset the conveyor. The plane moves at 20 miles an hour relative to the earth, and at 40 miles an hour relative to the conveyor. It's not as if the conveyor is holding the plane anchored to the ground via its retrograde motion.


Tom