Plane Problem

[[CoR]MiccyNarc]

Let's take it from the opposite direction: What if an airplane, going 600 mph, comes in to land on a treadmill going 600 mph the opposite direction. The plane doesn't lower its landing gear until it's low enough for the gear to actually touch the ground:

Well then, as others have noted, the only thing that makes a plane fly is the wings, or rather, that the wing is passing through air at high speed, generating lift as the air passes over the top faster than the air going under the wing.

You don't know jack **** about airplanes. GTFO this thread.

So if I grow a pair of giant metal wings I'll be able to fly if I'm not on a magical treadmill? FFS think before you post.

 

[Tak]

The plane isn't moving forward at all, it has to at some point initiate the forward motion!


Hold a model airplane above your head. Give it full power. Let go. The plane will fall, and then fly. Falling plus the force of the engines gives it enough lift that it is in flight.

If you give the plane a slight push forward with its full-power engines, then it will be flying. In this model, the plane's forward movement is cancelled by the treadmill. Without some forward movement, the plane can't generate lift.
​

 

[Crusher]

so if a plane could take of from a treadmill, why won't airports use this higly efficient use of space?

 

[User Name]

but when the plane is moving with 600mph and the mill does also move 600 mph in reverse, and the weels spin only 600 mph, where did the remaining 600 mph go?

It's neutralized.

600-600=0

So the jet can't move forward because it is being pulled backwards at the same rate.

 

[Lizardhands]

I think the problem is that the question isn't worded perfectly.

I took it to mean that the aeroplane is not moving in relation to the air around it -- in which case it won't take off. If you don't agree with that, you're wrong.

This relies on a certain level of friction in the wheels' bearings.

If friction in the wheels is low enough, they will just spin loads and loads, allowing the plane to move forward, because its forward acceleration is provided by jet engines.

 

[Tak]

Let's take it from the opposite direction: What if an airplane, going 600 mph, comes in to land on a treadmill going 600 mph the opposite direction. The plane doesn't lower its landing gear until it's low enough for the gear to actually touch the ground:

You don't know jack **** about airplanes. GTFO this thread.

So if I grow a pair of giant metal wings I'll be able to fly if I'm not on a magical treadmill? FFS think before you post.

Bad example. your plane already has the forward motion. Net forward movement in the problem given is zero. Without forward movement (causing the air to flow backwards over teh wigns), there is no lift.

 

[Xendance]

Ffs... it will happen exactly like in the .gif on that web page. The plane/wheels can't stand the energy, the plane collapses on the treadmill, goes back, hits the ground and the turbine rips off and flies straight forward because the opposing force disappeared in an instant.

And that is _if_ only the treadmill is mega

 

[Tak]

so if a plane could take of from a treadmill, why won't airports use this higly efficient use of space?

More moving parts means more stuff to break down, thus cost. You already pay too much for airline tickets!


But that alas is not the point of the thread.


*shoots the plane*

 

[Lizardhands]

so if a plane could take of from a treadmill, why won't airports use this higly efficient use of space?

Nobody's saying (I hope) that the plane will be able to take off from stationary. What some people are saying is that the plane will move forwards despite being on a treadmill.

 

[Moz]

oh god the stupidity is killing me

(the video is compressing)

 

[Tak]

oh god the stupidity is killing me

(the video is compressing)

I hope your video involves a model of the problem. Stationary winds, full power from the engine of some kind of lift-capable object, and no forward movement.


If you can make that fly, I'll mail you a dollar.

 

[[CoR]MiccyNarc]

Bad example. your plane already has the forward motion. Net forward movement in the problem given is zero. Without forward movement (causing the air to flow backwards over teh wigns), there is no lift.

You didn't answer the question.

If you admit that the plane will continue moving forward despite the treadmill then what is stopping it from accelerating in the first place?
Answer? Your stupidity.

 

[Lizardhands]

The problem posed doesn't give enough detail.
It has this magical treadmill which can match a plane's acceleration but does not say whether the plane's wheels are perfectly frictionless. It doesn't say how long the treadmill is. It is basically a ****ty question.

 

[Tak]

You didn't answer the question.

If you admit that the plane will continue moving forward despite the treadmill then what is stopping it from accelerating in the first place?
Answer? Your stupidity.

No, your picture in no way relates the equation. You formulated a different one.


EDIT: Try what I said about the model plane. Just release it and it will fall, because there is no forward movement innitiated. If you give it just the slightest push forward, then it will fly.

 

[User Name]

You didn't answer the question.

If you admit that the plane will continue moving forward despite the treadmill then what is stopping it from accelerating in the first place?
Answer? Your stupidity.

This is not about a plane already in flight! This is about a stationary plane. On a stationary treadmill. As the plane begins to attempt to pull forward using the thrust of it's engines. The treadmill begins to move backwards at EXACTLY the same rate. The platform they are both on remains stationary. So as long as the treadmill can keep up with the jets forward thrust by moving in the opposite direction. The jet will remain stationary on the platform. It will not move forward because it's forward thrust is being used to mantain it's position on the treadmill.

 

[Lizardhands]

ADVENTURE ROCKET SHIP
Inside a head parade
A message from the future
You crash upon a star

ATTENTION ROCKET SHIP
A message from the grave
You rock me like a pharoah
You crash upon a staaaaaaaaaaaaaaar

 

[Ruprecht]

its just a theoretical question, the lenght or friction doesnt matter here. will it fly or will it not, thats the question.

too bad i have to sleep now, or ill be a zombie at work tomorow. i would have loved to see explained how the hell 600 mph can disapear.

the formular 600-600 is just funny.
he said that plane accelerated (or moves) with 600mph and the mill goes with 600mph in the oposite direction and also saying the weels spinning with 600mph.

in my world PlaneMovement=600 + MillMovement=600 equal WeelSpin=1200.

 

[Folgore]

The engines will move the plane forwards, but in order to fly it need to go up as well. The 'up'-force or 'lift' is generated by air flowing past the wings. As no air flows past the wings in the example, the plane won't be able to take off.

 

[Moz]

this movie is taking awhile.

Plane = Car.

This is my thesis:

Car pushes against treadmill for forward motion, treadmill moves back, cancelled cars pushes.

Plane pushest against AIR for forward motion, treadmill moves back and does bubkiss to the plane. Plane goes forward and flies away.

 

[Lizardhands]

If there is no friction in the wheels, I'm pretty sure the plane will move forward and therefore take off, because the only force acting against it will be air resistance, which is of course far too low to prevent its acceleration. It's just like having a plane that doesn't touch the ground at all, but just sort of... levitates above it.


Edit: Moz is right. As long as the wheels are perfect and don't break due to the incredible speed they'll have to turn at.