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☖ Forums → Discussion Forum → Airplane on a conveyor belt
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Airplane on a conveyor belt
2007-03-10, 10:22 PM #121
Under, over, whatever, like I said I don't claim to understand exactly how jet engines work. But air must move past the wing in any case, which it doesn't if the plane is not moving through the air.
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2007-03-10, 10:24 PM #122
Originally posted by happydud:
Under, over, whatever, like I said I don't claim to understand exactly how jet engines work. But air must move past the wing in any case, which it doesn't if the plane is not moving through the air.


Yes it does, the engine moves the air. It creates a vacuum, the air rushes in to correct that. The air is moving around the plane. It's all relative; are you saying that there is no airflow around the plane with the engines on?
2007-03-10, 10:25 PM #123
The propellor isn't what pushes air over the airfoil, it's just what generates foreward thrust (this is more obvious in pusher-type planes that have the prop on the back instead of the nose and in jets, where the engines are in entirely the wrong position to somehow shoot air over the wings).

Kuat - I know you're intelligent, so I'm not going to get all Jon'C on you. Why not check out some aviation literature before making your argument?
COUCHMAN IS BACK BABY
2007-03-10, 10:27 PM #124
Originally posted by Tracer:
The propellor isn't what pushes air over the airfoil, it's just what generates foreward thrust (this is more obvious in pusher-type planes that have the prop on the back instead of the nose and in jets, where the engines are in entirely the wrong position to somehow shoot air over the wings).


What now?

We all agree the engines through some magic moves the air, right? What else would they be doing? This creates a flow of air, which then creates lift. I think I'll do an MS paint free body diagram...
2007-03-10, 10:28 PM #125
What the f is going on here?:psyduck:
COUCHMAN IS BACK BABY
2007-03-10, 10:33 PM #126
Originally posted by Tracer:
What the f is going on here?:psyduck:


Let's go through this step by step:

1.) The engines are on, prop or jet
2.) Both of these, in the end, are made to move air forward.
3.) This is airflow! Air is moving toward the plane now, right?
4.) This air, moving to the plane, acts upon the wings
5.) This generates lift
6.) Plane takes off.

Where in this does there need to be plane movement? Where is the error in this progression?
2007-03-10, 10:35 PM #127
Are you saying that the engines (prop or jet) are what push air over the wings and generate lift?
COUCHMAN IS BACK BABY
2007-03-10, 10:38 PM #128
FEAR NOT, MEATHEADS!

I AM EXPERT DIPLOMAT AND CAN PEACEFULLY RESOLVE YOUR CONTENTION

ALSO MY CAPSLOCK IS STILL BROKEN SEND HELP
2007-03-10, 10:38 PM #129
Originally posted by Tracer:
Are you saying that the engines (prop or jet) are what push air over the wings and generate lift?


Over and under. While yes, usually engines are located any number of places, in the end they create a flow of air that is then deflected by the wings to produce lift. Blow under a piece of paper. What happens? It moves up. Same deal, essentially. (I know it's supposed to deflect airflow over and under and it isn't completely equal but you get my point, right?)

Or you can wait for more elegant minds to explain it to you.
2007-03-10, 10:38 PM #130
Kuat you have things a little bit mixed up.

The engines push the plane forward, regardless of the conveyor belt which has almost no affect on the plane other than increasing the speed at which the wheels are spinning. Since the plane is moving forward that means air (which in this case is stationary) is traveling over the wings. This is what creates the lift. All the jets/props do is move the plane forward. They do nothing (directly) to actually lift the plane.

The bottom-line is: The only difference between a plane taking off on a conveyor belt and a plane taking off on a conventional runway is the speed at which the wheels are spinning. And since the only purpose of the wheels is to reduce friction between the plane and the ground, it doesn't matter how fast they spin.
2007-03-10, 10:41 PM #131
Originally posted by Vincent Valentine:
Kuat you have things a little bit mixed up.

The engines push the plane forward, regardless of the conveyor belt which has almost no affect on the plane other than increasing the speed at which the wheels are spinning. Since the plane is moving forward that means air (which in this case is stationary) is traveling over the wings. This is what creates the lift. All the jets/props do is move the plane forward. They do nothing (directly) to actually lift the plane.

The bottom-line is: The only difference between a plane taking off on a conveyor belt and a plane taking off on a conventional runway is the speed at which the wheels are spinning. And since the only purpose of the wheels is to reduce friction between the plane and the ground, it doesn't matter how fast they spin.


I don't agree with this; the plane would lift EVEN if it were tied in place. The engines DO move air. Why wouldn't they? The air is not stationary. What are the engines doing then?
2007-03-10, 10:43 PM #132
HERE IS MY CREDENTIALS:
Attachment: 15667/Gorbachev%20102.jpg (63,388 bytes)
2007-03-10, 10:44 PM #133
THIS IS THE REAL GORBACHEV, MIKHAIL GORBACHEV. HELLO.
2007-03-10, 10:44 PM #134
[http://www.flug-revue.rotor.com/FRheft/FRH9904/FR9904e1.JPG]

Explain to me how the jets will manage to move air over the wings, please.
2007-03-10, 10:47 PM #135
Originally posted by Vincent Valentine:
Explain to me how the jets will manage to move air over the wings, please.


Hold the presses! That's a jet!

All my life I thought it was a pig with a rocketpack.

Oh mercy, I am ruined!
2007-03-10, 10:48 PM #136
Wait are you admitting you were wrong or are you ridiculing me or are you being sarcastic or what? I seriously can't tell.
2007-03-10, 10:48 PM #137
They move air, so they move ALL of the air. :downs:

o.0
2007-03-10, 10:50 PM #138
All the air in the world!
2007-03-10, 10:58 PM #139
Originally posted by Vincent Valentine:
Wait are you admitting you were wrong or are you ridiculing me or are you being sarcastic or what? I seriously can't tell.


Take a wild guess.

You have increased velocity of air under the wing, correct? This decreases the pressure around the wings as per Bernoulli's principle, allowing some degree of lift. That isn't all there is to it, you also have the airflow being deflected by the wing, also generating some degree of lift. If airflow, moving under the wing, is deflected downwards, would that not cause the plane to feel a force upwards? Newton and that stuff...

We can both agree, with your marvelous photographic evidence the engines are under the wing. If the airflow is in any way caused to veer downwards by an element of the wing, what would happen?
2007-03-10, 10:59 PM #140
Heh you got Bernoulli's principle backwards there methinks.
Stuff
2007-03-10, 11:00 PM #141
Originally posted by kyle90:
Heh you got Bernoulli's principle backwards there methinks.


Yeah, that's what causes the thrust, my bad. But what do you say otherwise? Does the plane need to move forward to cause lift?

Edit: Damn daylight savings time. If my logic was bad, I expect to me mocked for a few pages when I return, heh...
2007-03-10, 11:03 PM #142
Yes; I've flown planes before and can attest to the fact that they don't go up unless they also go forward, no matter how high you have the engine throttled to. :P

ALTHOUGH if you have a headwind that is equal to or above take-off speed.... you don't go flying because seriously it's too goddamn windy.
Stuff
2007-03-10, 11:06 PM #143
It's irrelevant. Air needs to move past the wings, which isn't happening.

If you're moving forward, that causes air to move past the wings. If you're stationary, but there is enough wind for the wind moving past the wings to be equal to takeoff speeds, then you gain lift.
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2007-03-10, 11:07 PM #144
Originally posted by kyle90:
Yes; I've flown planes before and can attest to the fact that they don't go up unless they also go forward, no matter how high you have the engine throttled to. :P

ALTHOUGH if you have a headwind that is equal to or above take-off speed.... you don't go flying because seriously it's too goddamn windy.


Arg, this bothers me too much. First, let me see if I'm wrong about this:

The wings are deflected so the air is being forced downwards. If a jet is moving the air under a wing, and the air is forced down, doesn't the plane at least experience some degree of lift force? Wouldn't the air act on the plane in an equal and opposite direction?

Just say what's wrong with the above logic. Hopefully it is simple so I can go to bed.
2007-03-10, 11:07 PM #145
Problem solved. Hooray!

Wait, apparently not. What kyle90 means is that the engine isn't what passes air over the wing.
COUCHMAN IS BACK BABY
2007-03-10, 11:10 PM #146
Originally posted by Lord Kuat:
Arg, this bothers me too much. First, let me see if I'm wrong about this:

The wings are deflected so the air is being forced downwards. If a jet is moving the air under a wing, and the air is forced down, doesn't the plane at least experience some degree of lift force? Wouldn't the air act on the plane in an equal and opposite direction?

Just say what's wrong with the above logic. Hopefully it is simple so I can go to bed.


Well sure, a small amount of lift. Not enough to fly the plane though. Unless you're in a Harrier.
Stuff
2007-03-10, 11:11 PM #147
Originally posted by kyle90:
Well sure, a small amount of lift. Not enough to fly the plane though. Unless you're in a Harrier.


http://objection.mrdictionary.net/go.php?n=1795035

I just... wanted to use this. Sorry, even if I'm horribly wrong.
2007-03-10, 11:12 PM #148
Originally posted by Lord Kuat:
I don't agree with this; the plane would lift EVEN if it were tied in place. The engines DO move air. Why wouldn't they? The air is not stationary. What are the engines doing then?


Wow, you are retarded..
"it is time to get a credit card to complete my financial independance" — Tibby, Aug. 2009
2007-03-10, 11:14 PM #149
Originally posted by Freelancer:
Wow, you are retarded..


Lift is generated. It's not that OMG horrible of an idea; Kyle over there said that lift would be generated as well. Not enough to fly the plane in most cases, but generated none the less.
2007-03-10, 11:14 PM #150
You disappoint. Gorbachev would not use insult.
2007-03-10, 11:14 PM #151
Originally posted by Lord Kuat:
I'm horribly wrong.

Pretty much.
2007-03-10, 11:15 PM #152
Originally posted by Lord Kuat:
Lift is generated. It's not that OMG horrible of an idea; Kyle over there said that lift would be generated as well. Not enough to fly the plane in most cases, but generated none the less.


Um, you just said a plane would take off even if it was tied down. That's retarded.
"it is time to get a credit card to complete my financial independance" — Tibby, Aug. 2009
2007-03-10, 11:17 PM #153
Why must you hurt?
2007-03-10, 11:17 PM #154
Originally posted by Freelancer:
Um, you just said a plane would take off even if it was tied down. That's retarded.


I mean tied like a kite. As in, say at the tail of the plane a rope attached it to the end of something.

As in something to stop forward movement. I said tied in place, not tied down.
2007-03-10, 11:18 PM #155
Originally posted by Lord Kuat:
I mean tied like a kite. As in, say at the tail of the plane a rope attached it to the end of something.

As in something to stop forward movement.


Yeah. I know.
"it is time to get a credit card to complete my financial independance" — Tibby, Aug. 2009
2007-03-10, 11:18 PM #156
Ok people. The conveyor belt is not going to exert a force that is opposite of the THRUST of the plane. The plane will still move because the thrust of the jet/prop is pushing/pulling the plane forward. Newton's 3rd Law is fun kids! The only way that plane is staying put is if the NET FORCE of the plane is 0. That is the thrust vector is 90 degrees to the direction of travel or there is an equally retarding force on the plane. The engine is acting on the plane, the conveyor belt is acting on the wheels of the plane. Those wheels will spin but the plane will move forward.
Code to the left of him, code to the right of him, code in front of him compil'd and thundered. Programm'd at with shot and $SHELL. Boldly he typed and well. Into the jaws of C. Into the mouth of PERL. Debug'd the 0x258.
2007-03-10, 11:20 PM #157
Originally posted by Freelancer:
Yeah. I know.


But as was shown above, nothing is stopping the movement of air. Lift is generated, end of story. Maybe not enough to move every plane, but lift is indeed generated. With a hypothetical light plane at a severe angle, the plane would indeed lift off.

It's not the main cause of lift, but it isn't wrong. It's practically wrong, but theoretically it isn't, and that's what is being discussed here.

Look, vincent said this:

All the jets/props do is move the plane forward. They do nothing (directly) to actually lift the plane.

I was disagreeing with this, on the basis that you could generate lift by the wings directing the moving air downwards, the moving air generated by the engines.

Look, I agree with the fact the plane would move forward, and then fly. That's what is more important in this case, yes. I was approaching it from another angle that is physically possible. Ok, someone say why it isn't physically possible, if it's so obvious and I'm such a damned retard? Freelancer I'm looking at you.
2007-03-10, 11:27 PM #158
Originally posted by Lord Kuat:
But as was shown above, nothing is stopping the movement of air. Lift is generated, end of story. Maybe not enough to move every plane, but lift is indeed generated. With a hypothetical light plane at a severe angle, the plane would indeed lift off.

It's not the main cause of lift, but it isn't wrong. It's practically wrong, but theoretically it isn't, and that's what is being discussed here.

Look, vincent said this:

All the jets/props do is move the plane forward. They do nothing (directly) to actually lift the plane.

I was disagreeing with this, on the basis that you could generate lift by the wings directing the moving air downwards, the moving air generated by the engines.


For ****'s sake. That's like standing in the middle of the Mississippi River in the attempt to alter its course. Any lift generated by the engines themselves is negligible. Claiming that a plane could lift off in such a manner is 100% retarded.
"it is time to get a credit card to complete my financial independance" — Tibby, Aug. 2009
2007-03-10, 11:28 PM #159
I even drew a sodding picture!
Attachment: 15671/plane.jpg (51,771 bytes)
Code to the left of him, code to the right of him, code in front of him compil'd and thundered. Programm'd at with shot and $SHELL. Boldly he typed and well. Into the jaws of C. Into the mouth of PERL. Debug'd the 0x258.
2007-03-10, 11:31 PM #160
I like the American picture.
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