You have a plane and a conveyor belt.

[jlee]

Originally posted by: Evadman

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.

Quoted for posterity so we can all laugh later.

I think many of us (myself included) are misunderstanding the situation -- as a former student pilot (powered & glider) myself, I have an idea how these things fly..if you take this from the OP:

belt moves in reverse exactly as fast as the wheels move forward.

The wheels would necessarily rotate in direct proportion to the speed of the aircraft, which would leave me assuming that the aircraft is remaining in one position on the ground. Without a headwind, it couldn't take off.

What am I missing?

Edit: Which direction is reverse?

 

[mrSHEiK124]

Originally posted by: Evadman

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.

Quoted for posterity so we can all laugh later.

In-freakin-deed. The wheels have nothing to do with an airplane taking off, put the engines at full thrust and fly away.

 

[NanoStuff]

Originally posted by: myusername

Originally posted by: JMWarren
I'm still not so sure. If the plane isn't moving forward in space there is no air flow over the wings.

THAT is correct. Except the plane IS moving forward. Imagine being on a treadmill with roller blades. By hanging onto the sides, you hold yourself constant against the moving conveyor. If you pull yourself forward by your arms, you will move forward against the conveyor belt, even if the conveyor increases in speed. Now, instead of pulling yourself forward by your arms, stick a jet engine on your back.

Your body may lean forward, but your feet and roller blades will stay behind. Unless the plane is capable of detaching from it's wheels, no go.

 

[thirdlegstump]

Originally posted by: myusername

Originally posted by: deathkoba
I'm a private pilot with instrument license.

Bully for you. NO one is questioning that the plane must be moving to create lift. The only question is whether the plane moves. The answer is yes, and you can figure out why for yourself.

Move backwards or forwards? That depends on whether the engine is providing + or - the necessary thrust to counter the conveyor belt's movement.

 

[JMWarren]

This wouldn't even really change take off distance. I think the initial problem is people picutre the plane lifting off the treadmill without forward velocity.

 

[jlee]

Originally posted by: mrSHEiK124

Originally posted by: Evadman

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.

Quoted for posterity so we can all laugh later.

In-freakin-deed. The wheels have nothing to do with an airplane taking off, put the engines at full thrust and fly away.

Assuming you could overcome the speed of the belt, no?

I must be missing something completely obvious..

Originally posted by: JMWarren
This wouldn't even really change take off distance. I think the initial problem is people picutre the plane lifting off the treadmill without forward velocity.

That's what I'm trying to figure out..

You could take off with backwards movement, providing you had enough of a headwind..

 

[thirdlegstump]

Originally posted by: mrSHEiK124

Originally posted by: Evadman

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.

Quoted for posterity so we can all laugh later.

In-freakin-deed. The wheels have nothing to do with an airplane taking off, put the engines at full thrust and fly away.

Hm...let's simply put it this way....

The aircraft will not take off until ENOUGH HEADWIND is generated in ANY way. The aircraft's flight performance is entirely dependent on airspeed, not groundspeed. Couple that with common sense and well..enough already. Maybe I woke up in the twilight zone.

 

[Evadman]

Originally posted by: NanoStuff

Originally posted by: myusername

Originally posted by: JMWarren
I'm still not so sure. If the plane isn't moving forward in space there is no air flow over the wings.

THAT is correct. Except the plane IS moving forward. Imagine being on a treadmill with roller blades. By hanging onto the sides, you hold yourself constant against the moving conveyor. If you pull yourself forward by your arms, you will move forward against the conveyor belt, even if the conveyor increases in speed. Now, instead of pulling yourself forward by your arms, stick a jet engine on your back.

Your body may lean forward, but your feet and roller blades will stay behind. Unless the plane is capable of detaching from it's wheels, no go.

That analogy needs to be fixed slightly to replate to how a plane works.

1. You are on a treadmill wearing rollerblades
2. You are holding onto a rope bolted into the wall
3. The treadmill moves backwards at the same rate you move forwards

Can you pull yourself off the treadmill?

Answer: Yes. But the wheels on the rollerblades will move at 2x the speed you are pulling yourself forwards

Originally posted by: deathkoba
The aircraft will not take off until ENOUGH HEADWIND is generated in ANY way. The aircraft's flight performance is entirely dependent on airspeed, not groundspeed.

You just proved that your first post was wrong. That is what you meant to do right?

 

[PowerMacG5]

Ugh, repost. Anyone that thinks it doesn't take off is a fvcking idiot. The plane takes off because it relies on air speed, not ground speed. The jets/propellers/rocket/whatever accelerates it through the air. It doesnt matter if the conveyor is moving backwards at 2000 km/hr, the plane will still take off because it's jets can overcome the frictional force imparted on the bearings by the conveyor.

 

[thirdlegstump]

Originally posted by: CadetLee

Originally posted by: mrSHEiK124

Originally posted by: Evadman

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.

Quoted for posterity so we can all laugh later.

In-freakin-deed. The wheels have nothing to do with an airplane taking off, put the engines at full thrust and fly away.

Assuming you could overcome the speed of the belt, no?

I must be missing something completely obvious..

Originally posted by: JMWarren
This wouldn't even really change take off distance. I think the initial problem is people picutre the plane lifting off the treadmill without forward velocity.

That's what I'm trying to figure out..

You could take off with backwards movement, providing you had enough of a headwind..

Exactly.

Say we're talking about a Cessna 172R. It has a general take off speed of around 55knots. If there is a 55knot headwind and the conveyor belt is going at 55knots while the plane's engines are producing enough thrust to keep the aircraft's positional (ground) speed at 0knots (meaning the plane is NOT moving at all.....) then the plane should be able to take off. It would look very odd but it is possible. If there was an even greater headwind, the plane could actually travel backwards (to the person watching this event).

 

[thirdlegstump]

Originally posted by: Evadman

Originally posted by: NanoStuff

Originally posted by: myusername

Originally posted by: JMWarren
I'm still not so sure. If the plane isn't moving forward in space there is no air flow over the wings.

THAT is correct. Except the plane IS moving forward. Imagine being on a treadmill with roller blades. By hanging onto the sides, you hold yourself constant against the moving conveyor. If you pull yourself forward by your arms, you will move forward against the conveyor belt, even if the conveyor increases in speed. Now, instead of pulling yourself forward by your arms, stick a jet engine on your back.

Your body may lean forward, but your feet and roller blades will stay behind. Unless the plane is capable of detaching from it's wheels, no go.

That analogy needs to be fixed slightly to replate to how a plane works.

1. You are on a treadmill wearing rollerblades
2. You are holding onto a rope bolted into the wall
3. The treadmill moves backwards at the same rate you move forwards

Can you pull yourself off the treadmill?

Answer: Yes. But the wheels on the rollerblades will move at 2x the speed you are pulling yourself forwards

Originally posted by: deathkoba
The aircraft will not take off until ENOUGH HEADWIND is generated in ANY way. The aircraft's flight performance is entirely dependent on airspeed, not groundspeed.

You just proved that your first post was wrong. That is what you meant to do right?

No.

 

[myusername]

Originally posted by: NanoStuff
Your body may lean forward, but your feet and roller blades will stay behind. Unless the plane is capable of detaching from it's wheels, no go.

You are mistaken. Try it and get back to us when you have.

 

[NanoStuff]

Originally posted by: Evadman
That analogy needs to be fixed slightly to replate to how a plane works.

1. You are on a treadmill wearing rollerblades
2. You are holding onto a rope bolted into the wall
3. The treadmill moves backwards at the same rate you move forwards

Can you pull yourself off the treadmill?

Answer: Yes. But the wheels on the rollerblades will move at 2x the speed you are pulling yourself forwards

The thing about this is, the treadmill moves backwards at the rate the wheels rotate forwards, not at the rate the plane moves forwards

 

[myusername]

Originally posted by: NanoStuff

Originally posted by: Evadman
That analogy needs to be fixed slightly to replate to how a plane works.

1. You are on a treadmill wearing rollerblades
2. You are holding onto a rope bolted into the wall
3. The treadmill moves backwards at the same rate you move forwards

Can you pull yourself off the treadmill?

Answer: Yes. But the wheels on the rollerblades will move at 2x the speed you are pulling yourself forwards

The thing about this is, the treadmill moves backwards at the rate the wheels rotate forwards, not at the rate the plane moves forwards

BAN

 

[Umberger]

Originally posted by: D1gger
The wheels are not driving the plane forward, the engines are, so the plane moves forward until the air passing over the wings gives it enough lift to take off. The wheels spinning on the conveyor belt have absolutely nothing to do with the physics of a plane flying.

AGREED. I hate this question.

 

[Number1]

There is nothing that keeps the plane from moving forward. It WILL take off.

 

[NanoStuff]

Originally posted by: myusername

Originally posted by: NanoStuff
Your body may lean forward, but your feet and roller blades will stay behind. Unless the plane is capable of detaching from it's wheels, no go.

You are mistaken. Try it and get back to us when you have.

I'll do that if you built a conveyor belt and buy a plane

 

[thirdlegstump]

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.

 

[jlee]

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.

Assuming that friction was not part of the equation, the aircraft could take no action and the conveyor could pick up speed, yet the aircraft would remain stationary. I think that's the (impossible) scenario that they're assuming.

 

[Number1]

What does the speed rotation of the wheel has to do with the forward motion of the plane?

 

[thirdlegstump]

Originally posted by: CadetLee

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.

Assuming that friction was not part of the equation, the aircraft could take no action and the conveyor could pick up speed, yet the aircraft would remain stationary. I think that's the (impossible) scenario that they're assuming.

Yes, and to remain stationary, the pilot would have to keep adjusting engine thrust to counter the change in velocity of the conveyor belt, assuming that the plane has zero airspeed and the conveyor operator keeps fvcking with the controls

 

[jlee]

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.

 

[LordMorpheus]

Originally posted by: Rainsford
Uh, no...airflow over the wing provides lift...and that requires the plane to be moving...which it wouldn't be doing.

It would if it didn't have the brakes on - the conveyor belt spinning backwards wouldn't stop the plane from moving forwards if the pilot didn't have the brakes on - It would look like a normal takeoff except the wheels would be spinning faster.

In other words, the conveyor belt wouldn't give the plane a ground speed of zero because the gear on aircraft just freewheel unless the brakes are applied.

 

[jlee]

Originally posted by: LordMorpheus

Originally posted by: Rainsford
Uh, no...airflow over the wing provides lift...and that requires the plane to be moving...which it wouldn't be doing.

It would if it didn't have the brakes on - the conveyor belt spinning backwards wouldn't stop the plane from moving forwards if the pilot didn't have the brakes on - It would look like a normal takeoff except the wheels would be spinning faster.

In other words, the conveyor belt wouldn't give the plane a ground speed of zero because the gear on aircraft just freewheel unless the brakes are applied.

If you put a car in neutral and the ground moves, the car won't remain stationary unless friction did not exist.

I see what you're saying, though.

 

[thirdlegstump]

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

The plane is assumably grounded on the conveyor belt.

There are other factors that make this question faulty like how fast is the conveyor belt moving? What kind of plane? In other words, does the plane have an engine powerful enough to keep the plane in one spot + more power necessary to drive the plane fast enough to generate enough headwind to actually gain headspeed necessary for takeoff?