You have a plane and a conveyor belt.

[thirdlegstump]

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 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.

This is correct.

 

[thirdlegstump]

Originally posted by: 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.

Wrong.

 

[speg]

WE JUST DID THIS THREAD LAST MONTH :|

 

[FeuerFrei]

You freaks who somehow convinced yourself it would take off need to go back and read the OP. The conveyor is moving backwards while the plane rolls forward, COMPLETELY NEGATING any forward progress the plane would make. The conveyor would speed up to match the increasing thrust of the plane and thus the motion of the plane would be imperceptible and airspeed would = 0. Basically, the plane is static in airspace and the ground is moving beneath it... that is all.

This thread is not for arguing whether a plane could take off on a conveyor belt, PERIOD. Naturally a plane would eventually accellerate enought to achieve airspeed (if the conveyor stayed at a constant pace) it would just take longer to launch.

 

[Armitage]

Originally posted by: deathkoba
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.

By "visually stationary" I assume you mean stationary WRT everything that is not the conveyor. Re-read the question. It never says that, only that the conveyor moves backward as fast as the wheels move forward.

 

[Armitage]

Originally posted by: deathkoba

Originally posted by: 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.

Wrong.

LMAO, well that's convincing.
Care to elaborate?

 

[mercanucaribe]

Originally posted by: CadetLee

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.

Cars drive using their wheels... planes don't.

 

[jlee]

Originally posted by: Armitage

Originally posted by: deathkoba
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.

By "visually stationary" I assume you mean stationary WRT everything that is not the conveyor. Re-read the question. It never says that, only that the conveyor moves backward as fast as the wheels move forward.

Wheelspeed is directly proportional to aircraft speed until traction is lost (ie takeoff).

 

[Armitage]

Here's the previous thread if anybody cares
http://forums.anandtech.com/messageview...atid=38&threadid=1800873&enterthread=y

 

[alien42]

i am going with the no takeoff camp

if there is no forward motion of the plane because of the conveyor belt then the plane will not take off

 

[tommywishbone]

If the plane in question is a Northwest Airlines plane, it may take-off eventually, but it will certainly be late and they will certainly lose my luggage.


I'm guessing no. If the plane is stationary, how does any air flow past the wings and create lift?

 

[Armitage]

Originally posted by: CadetLee

Originally posted by: Armitage

Originally posted by: deathkoba
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.

By "visually stationary" I assume you mean stationary WRT everything that is not the conveyor. Re-read the question. It never says that, only that the conveyor moves backward as fast as the wheels move forward.

Wheelspeed is directly proportional to aircraft speed until traction is lost (ie takeoff).

Unless some madman put a conveyor belt under your plane in a vain attempt to keep you from taking off

 

[skyking]

Originally posted by: tommywishbone
If the plane in question is a Northwest Airlines plane, it may take-off eventually, but it will certainly be late and they will certainly lose my luggage.


I'm guessing no. If the plane is stationary, how does any air flow past the wings and create lift?

If it is stationary relative to the airmass, it does not. /thread.

 

[NanoStuff]

Originally posted by: deathkoba
Was the conveyor belt already spinning while the plane was "placed" on there until the wheels spun?

The belt doesn't move until the plane adds thrust. The starting situation would be a plane and a conveyor belt without movement.

My question to the people that say it will take off is this:

If the wheels have to be rotating faster than the conveyor belt to advance forward, how does the plane move forward if the belt doesn't allow for the wheels to rotate faster than the belt is moving backwards?

If you're assuming the wheels will rotate forward at twice the speed they would normally, note the belt is also moving backwards at that speed.

 

[Evadman]

I am done with this thread. I am beginning to understand why Japan schooling is better than the system in the U.S. This is just sad.

My last comment:
The plane takes off. Everyone who thinks it doesn't, please think about the difference between how a car and person produce thrust (tire pusing against the ground, feet pusing against the ground) and how a plane produces thust (propeller or jet pushing against the air). Once you undertand the difference between those, then you will undertand why the plane takes off. Heck, the pilot probably wouldn't even notice if the runway started moving backwards.

 

[imported_Pablo]

THIS IS STUPID. THE OP IS UNCLEAR.

 

[NanoStuff]

Originally posted by: Pablo
THIS IS STUPID. THE OP IS UNCLEAR.

I'm happy to clarify , what's the confusion?

 

[alien42]

Originally posted by: Evadman
I am done with this thread. I am beginning to understand why Japan schooling is better than the system in the U.S. This is just sad.

My last comment:
The plane takes off. Everyone who thinks it doesn't, please think about the difference between how a car and person produce thrust (tire pusing against the ground, feet pusing against the ground) and how a plane produces thust (propeller or jet pushing against the air). Once you undertand the difference between those, then you will undertand why the plane takes off. Heck, the pilot probably wouldn't even notice if the runway started moving backwards.

you seem to be missing the basic concept that airplane wings can only 'lift' with airflow and there is no airflow in this scenerio. your logic as explained makes no sense.

 

[tommywishbone]

If the plane does take-off, why do we even have airports? We could just place conveyor belts everywhere and planes could take-off anywhere.

 

[alien42]

here is an analogy from me:

put your car on a dyno and drive as fast as you can with a balsa wood toy plane out the window. when you let go of the plane it will fall straight down because there is no airflow.

 

[oznerol]

Originally posted by: alien42

Originally posted by: Evadman
I am done with this thread. I am beginning to understand why Japan schooling is better than the system in the U.S. This is just sad.

My last comment:
The plane takes off. Everyone who thinks it doesn't, please think about the difference between how a car and person produce thrust (tire pusing against the ground, feet pusing against the ground) and how a plane produces thust (propeller or jet pushing against the air). Once you undertand the difference between those, then you will undertand why the plane takes off. Heck, the pilot probably wouldn't even notice if the runway started moving backwards.

you seem to be missing the basic concept that airplane wings can only 'lift' with airflow and there is no airflow in this scenerio. your logic as explained makes no sense.

This is also my logic.

I understand that the plane does not need friction with the ground to go forward. But I didn't think that was the question. Since the engines would only make it go forward faster, and the conveyor belt will simply counteract that, what exactly is making the plane go "up"?

There is no upward force on the plane, unless the engines are tilted upward, and if that's the case then it would probably take off. Otherwise not.

 

[Armitage]

Originally posted by: alien42

Originally posted by: Evadman
I am done with this thread. I am beginning to understand why Japan schooling is better than the system in the U.S. This is just sad.

My last comment:
The plane takes off. Everyone who thinks it doesn't, please think about the difference between how a car and person produce thrust (tire pusing against the ground, feet pusing against the ground) and how a plane produces thust (propeller or jet pushing against the air). Once you undertand the difference between those, then you will undertand why the plane takes off. Heck, the pilot probably wouldn't even notice if the runway started moving backwards.

you seem to be missing the basic concept that airplane wings can only 'lift' with airflow and there is no airflow in this scenerio. your logic as explained makes no sense.

Wow - this is amazing. It's like trying to explain color to a blind man.

THERE IS AIRFLOW BECAUSE THE PLANE IS MOVING. The conveyor belt is IRRELEVANT.

I'm with Evadman - done with this topic, though I may check in for laughs.

 

[PowerMacG5]

Originally posted by: FeuerFrei
You freaks who somehow convinced yourself it would take off need to go back and read the OP. The conveyor is moving backwards while the plane rolls forward, COMPLETELY NEGATING any forward progress the plane would make. The conveyor would speed up to match the increasing thrust of the plane and thus the motion of the plane would be imperceptible and airspeed would = 0. Basically, the plane is static in airspace and the ground is moving beneath it... that is all.

This thread is not for arguing whether a plane could take off on a conveyor belt, PERIOD. Naturally a plane would eventually accellerate enought to achieve airspeed (if the conveyor stayed at a constant pace) it would just take longer to launch.

Ok, you are an idiot. The plane does not use it's wheels for motion.

Assuming the plane has get engines:
It uses the jet engines. The jets do not give a fvck what the ground is doing. With a plane, you have to realize there are basically two roads. The ground and the air. Your car is moving using the ground, the plane the air. The jets push on the air, not the ground. If you still feel you are correct, think of it this way. A car cannot drive well on the ice, but a plane can take off perfectly fine, traveling in a perfectly straight line.

If you don't believe me, then you are a fvcking moron who will get no where in life because he doesn't understand a basic thing. I am sick of all these morons here not understanding basic physics.

 

[thirdlegstump]

Originally posted by: Evadman
I am done with this thread. I am beginning to understand why Japan schooling is better than the system in the U.S. This is just sad.

My last comment:
The plane takes off. Everyone who thinks it doesn't, please think about the difference between how a car and person produce thrust (tire pusing against the ground, feet pusing against the ground) and how a plane produces thust (propeller or jet pushing against the air). Once you undertand the difference between those, then you will undertand why the plane takes off. Heck, the pilot probably wouldn't even notice if the runway started moving backwards.

Wrong. Actually the pilot will notice that either his airspeed indicator is broken or that he might've entered the twilight zone because he looks like he's going so fast but there's absolutely no resistance to his controls.

As for your comment on Japanese schooling, I am Japanese myself so I don't know what you're talking about.

 

[Armitage]

Originally posted by: alien42
here is an analogy from me:

put your car on a dyno and drive as fast as you can with a balsa wood toy plane out the window. when you let go of the plane it will fall straight down because there is no airflow.

Ok, one more post.
Tie an F15 down on that Dyno. Spool up to full afterburner thrust - 50,000 lbs. I hope your tiedowns hold. How many HP does your dyno read?

0 nada none zilch.
No horsepower at the wheels. But yet an F15 can clearly takeoff.

Why?
BECAUSE IT DOESN'T USE THE WHEELS TO ACCELERATE.