You have a plane and a conveyor belt.

[Number1]

Originally posted by: CadetLee

Originally posted by: Number1
What does the speed rotation of the wheel has to do with the forward motion of the plane?

Assuming that the wheels have contact with the ground, forward motion of the plane would necessarily result in rotation of the wheels.

So the plane moves forward, accelerates an takes off. After all if the plane in not moving, the wheel are not turning and the treadmill is stationary. If the tread mill is moving, then the plane must be moving forward.

 

[thirdlegstump]

Does this hypothetical plane have VTOL capabilities? hehe

 

[thirdlegstump]

Originally posted by: Number1

Originally posted by: CadetLee

Originally posted by: Number1
What does the speed rotation of the wheel has to do with the forward motion of the plane?

Assuming that the wheels have contact with the ground, forward motion of the plane would necessarily result in rotation of the wheels.

So the plane moves forward, accelerates an takes off. After all if the plane in not moving, the wheel are not turning and the treadmill is stationary. If the tread mill is moving, then the plane must be moving forward.

We need a wheelchair for your brain.

 

[FeuerFrei]

What is the airspeed of an unladen African aircraft on a conveyor belt???

 

[Evadman]

Originally posted by: deathkoba

Originally posted by: Number1
There is nothing that keeps the plane from moving forward. It WILL take off.

QFI (idiocy)

There is a conveyor belt moving foward underneath the plane sir.

May I suggest you quote yourself if you are QFI. Get back to us when you know how a plane produces thrust. Then you will find out that what the ground does under a plane is immaterial.

If what the ground did mattered, then it would be impossible for a plane to fly west to east. The earth is rotating at 1020 miles an hour at the equator (24500 miles circumfrence in 24 hours = 24500 / 24 = 1020 miles/hr), which would be -1020 miles an hour to a plane flying west to east. The plane would go up and move farther west unless it was going at least 1041 miles an hour.

By the same token, a plane flying from new york to los angeles would basicly have a 1020 mph tailwind. That means a comercial airliner would be able to make the flight in about 3 hours.

Note to the physics people: I am trying to make a point. I know, I know.

 

[Number1]

Pee brain I see. At the risk of repeting myself, the plane will take off. There is nothing that keeps the prop from moving the plane forward trough the air.

You are making a fool of yourself.

 

[jlee]

If what the ground did mattered, then it would be impossible for a plane to fly west to east. The earth is rotating at 1020 miles an hour at the equator (24500 miles circumfrence in 24 hours = 24500 / 24 = 1020 miles/hr), which would be -1020 miles an hour to a plane flying west to east. The plane would go up and move farther west unless it was going at least 1041 miles an hour.

So you concede that for this argument, friction must not exist...? If you put any vehicle (in neutral) on a belt, it will move in the direction the belt is moving.

Are we arguing hypothetically or realistically?

Originally posted by: Number1
Pee brain I see. At the risk of repeting myself, the plane will take off. There is nothing that keeps the prop from moving the plane forward trough the air.

You are making a fool of yourself.

You aren't doing so bad either. AT needs spellcheck.

 

[thirdlegstump]

Originally posted by: Evadman

Originally posted by: deathkoba

Originally posted by: Number1
There is nothing that keeps the plane from moving forward. It WILL take off.

QFI (idiocy)

There is a conveyor belt moving foward underneath the plane sir.

May I suggest you quote yourself if you are QFI. Get back to us when you know how a plane produces thrust. Then you will find out that what the ground does under a plane is immaterial.

If what the ground did mattered, then it would be impossible for a plane to fly west to east. The earth is rotating at 1020 miles an hour at the equator (24500 miles circumfrence in 24 hours = 24500 / 24 = 1020 miles/hr), which would be -1020 miles an hour to a plane flying west to east. The plane would go up and move farther west unless it was going at least 1041 miles an hour.

By the same token, a plane flying from new york to los angeles would basicly have a 1020 mph tailwind. That means a comercial airliner would be able to make the flight in about 3 hours.

Note to the physics people: I am trying to make a point. I know, I know.

Actually I tend to agree with this assessment but you're missing the 'transition' part of the equation where there's actually ground (conveyor belt) involved prior to the take off.

 

[jlee]

The earth's rotation is irrelevant anyway, since the atmosphere rotates with it.

 

[Mo0o]

Repost, and yes it would take off. The plane is not propelled forward by the wheels but by the turbines, despite teh wheels turning backwards, the plane WILL still take off. Imagine you holding a little toy car on a treadmill thats ramping up. Will it really take that much effort to push it up the treadmill?

 

[Number1]

What, you can't figure it out either so you pick on my spelling?

 

[Mo0o]

http://www.straightdope.com/columns/060203.html

 

[Evadman]

Originally posted by: CadetLee
So you concede that for this argument, friction must not exist...? If you put any vehicle (in neutral) on a belt, it will move in the direction the belt is moving.

Wait, what? Friction doesn't matter in my example, or in the original question. Friction is negligible at best. The wheels are not bolted to the belt. If a plane is pushing against the AIR with a 400 HP engine, then the only way for the plane to stay stationary to an observer (while on the belt) is for the bearings on the wheels to dissapate 400 HP. the coeficent of friction on a decent bearing is a whole lot of nothing. If, say, the belt were moving at about 20,000 times the forward speed of the aircraft, then friction may play a role. But since the belt is moving at the same speed as the plane, except in reverse, then friction plays no part.

 

[jlee]

Originally posted by: Evadman

Originally posted by: CadetLee
So you concede that for this argument, friction must not exist...? If you put any vehicle (in neutral) on a belt, it will move in the direction the belt is moving.

Wait, what? Friction doesn't matter in my example, or in the original question. Friction is negligible at best. The wheels are not bolted to the belt. If a plane is pushing against the AIR with a 400 HP engine, then the only way for the plane to stay stationary to an observer (while on the belt) is for the bearings on the wheels to dissapate 400 HP. the coeficent of friction on a decent bearing is a whole lot of nothing. If, say, the belt were moving at about 20,000 times the forward speed of the aircraft, then friction may play a role. But since the belt is moving at the same speed as the plane, except in reverse, then friction plays no part.

Alright, I see what you're saying.

This question sucks.

 

[thirdlegstump]

Originally posted by: Evadman

Originally posted by: CadetLee
So you concede that for this argument, friction must not exist...? If you put any vehicle (in neutral) on a belt, it will move in the direction the belt is moving.

Wait, what? Friction doesn't matter in my example, or in the original question. Friction is negligible at best. The wheels are not bolted to the belt. If a plane is pushing against the AIR with a 400 HP engine, then the only way for the plane to stay stationary to an observer (while on the belt) is for the bearings on the wheels to dissapate 400 HP. the coeficent of friction on a decent bearing is a whole lot of nothing. If, say, the belt were moving at about 20,000 times the forward speed of the aircraft, then friction may play a role. But since the belt is moving at the same speed as the plane, except in reverse, then friction plays no part.

A ball bearing itself sure, very little friction, in fact that's what it's designed for. Now put a few tons on one side of the bearing and well..you see my point?

 

[thirdlegstump]

Bah. I give up. Head hurts. Gonna go chew on my gf's nipples or something.

 

[Mo0o]

Originally posted by: deathkoba

Originally posted by: Evadman

Originally posted by: CadetLee
So you concede that for this argument, friction must not exist...? If you put any vehicle (in neutral) on a belt, it will move in the direction the belt is moving.

Wait, what? Friction doesn't matter in my example, or in the original question. Friction is negligible at best. The wheels are not bolted to the belt. If a plane is pushing against the AIR with a 400 HP engine, then the only way for the plane to stay stationary to an observer (while on the belt) is for the bearings on the wheels to dissapate 400 HP. the coeficent of friction on a decent bearing is a whole lot of nothing. If, say, the belt were moving at about 20,000 times the forward speed of the aircraft, then friction may play a role. But since the belt is moving at the same speed as the plane, except in reverse, then friction plays no part.

A ball bearing itself sure, very little friction, in fact that's what it's designed for. Now put a few tons on one side of the bearing and well..you see my point?

No the frictional force simply isn't enough. Read the link I provided

 

[vshah]

Originally posted by: deathkoba
You people are retarded. It will not take off as the sole lift mechanism (the wings) will not be getting any airflow. The engines only push the aircraft so that enough air can flow over the wings. Only then will the aircraft achieve any level of lift. I'm a private pilot with instrument license.

Now if there is enough headwind, even when the plane is visually stationary, it's possible that the headwind itself can push the plane up a bit but it would be very uncontrolled and will simply flip the plane over.

hehe dum dum...see the straigh tdope link

 

[Number1]

lol

 

[Armitage]

OMG not again ((
Yes, it takes off. Absolutely. The wheels are just spinning twice as fast as they would be on a normal takeoff.

Again, for anybody that's ever taken phyisics, draw the free body diagram and tell me what force opposes the forward motion of the plane?

That's right NOTHING except the friction of the wheels and air drag. The air drag is identical to the normal takeoff, and the rolling resistance of the wheels which is only neglibly higher due to the higher rotation rate.

 

[Quasmo]

say you are going to jump over a 10 foot ditch, you need to be running 10 mph to jump over said ditch. What some people are saying is that if you had a treadmill on the side you were jumping from and you started running and got up to 10 mph on the treadmill, and jumped forward on that treadmill you will be able to jump over that ditch, it's absolutely proposterous. Planes need a certain speed to produce lift, when air flows over the wings, if the wings stay stationary, on the concieved treadmill, you will get no lift and will not take off, it is as simple as that. Now if the treadmill stopped, then airplane kept going then yes it would take off.

 

[Evadman]

Originally posted by: deathkoba
A ball bearing itself sure, very little friction, in fact that's what it's designed for. Now put a few tons on one side of the bearing and well..you see my point?

I understand what you are trying to say, but you are applying the right rule to the wrong question.

I don't know how else to explain it. You have enough knowledge to think you are correct, but not enough to know the right answer, and you are either unwilling or unable to accept the analogies that others are giving. I don't know how to convince you without you seeing it yourself, and doing that in a text based forum without a plane is kinda difficult.

 

[skyking]

If the plane can move relative to the airmass, it flies. If it cannot, it does not.
The conveyor and all that other gibberish is smokescreen for the real issue, relative motion to the medium of flight, which is air.

If the wind is strong enough, you can get airborne with out any forward motion over the ground. I've been in strong enough winds that I could hover in place and even move backwards over the ground.
One time we were flying an ILS in a 152, and the controller asked us if we were planning to finish that approach

We had to bag it for the day and find a sheltered airport to land.

 

[thirdlegstump]

Questions that need to be answered........

Was the conveyor belt already spinning while the plane was "placed" on there until the wheels spun? Was the engine even on? If it was, was it producing enough thrust to counter the reverse motion of the aircraft caused by the friction of the wheel?

My understanding of this situation is looking at it from a real world perspective where an airplane is initially placed on a non-moving conveyor belt. The conveyor belt then starts spinning while the aircraft's engines are revving up to equally counter the backwards movement created by the gradual increase in conveyor belt movement. There is no ball bearing in the world that can keep the plane stationary without some form of help; the engine's sheer thrust.

In this situation if there is no headwind and the aircraft is visually stationary, it simply cannot take off unless the engines produce enough thrust to further counter this backwards force and produce enough artificial headwind (forward visual movement) to satisfy the aircraft's take off requirements.

With headwind, it further complicates this matter. Unless I am crazy, I think I'm dead on.

 

[Armitage]

Originally posted by: Quasmo
say you are going to jump over a 10 foot ditch, you need to be running 10 mph to jump over said ditch. What some people are saying is that if you had a treadmill on the side you were jumping from and you started running and got up to 10 mph on the treadmill, and jumped forward on that treadmill you will be able to jump over that ditch, it's absolutely proposterous. Planes need a certain speed, not "acceleration" to produce lift, when air flows over the wings, if the wings stay stationary, on the concieved treadmill, you will get no lift and will not take off, it is as simple as that. Now if the treadmill stopped, then airplane kept going then yes it would take off.

Your analogu is FUBAR
Somebody running produces their forward motion by friction with the ground. They can only move relative to the ground. I fhtey are on a treadmill they can only move relative to the treadmill belt.

A plane move forward by moving air backwards. It doesn't matter what the ground is doing under it. It has thrust on the conveyer in the same way it has thrust at 10,000 fy

Actually, you analogy of the treadmill next to the ditch shows exactly why the plane does take off! Think about it, if the plane relied on friction the stationary ground to generate takeoff speed, it would fall back to the ground as soon as it lifts off - just like the runner in your analogu.