Plane Problem

[Moz]

As an actual pilot myself, my only response to this whole thread is

TL;DR

edit:

Since it seems this whole thread is massive. Let me state very clearly.

It doesn't matter that the ground is doing, whether the plane has wheels or even if its moving. The only thing required for an airfoil (IE, WING) to produce lift is airflow (wind) over the wings from the front. Nothing else matters.

Nothing.

The groundspeed is irrelevant, wheels are irrelevant. All they do is reduce friction with the ground. You could take a plane of without wheels...

Infact, engines are irrelevant too. Infact I used to do it all the time.

The plane has thrust (The engines still work) so figure it out yourselves you idiots.

 

[User Name]

Again, take a treadmill, put a toy car on it, and make the treadmill run as fast as possible while pushing the car forward. You will see the wheels spinning VERY FAST but guess what! The car will accelerate as long as you are pushing it.

Same damn principle applies. The wheels support the plane, that is all. A force completely seperate from the wheels, and the ground, is pushing the plane. All that matters is how fast the air is moving and how much force the engines are pushing.

If the plane is moving 400 mph then the air around the plane is moving 400 mph and IT WILL TAKE OFF. Treadmill can't stop it.

The air around the plane is stationary. It's the runway that's moving 400 MPH. Therefore it will not take off

 

[[CoR]MiccyNarc]

Friend made this flash for the last time this question was asked on another forum:
http://img310.imageshack.us/my.php?image=airplane2nx.swf

 

[Nestor Makhno]

Why is the air around the plane moving at 400 mph? tractor fields? magic? Ever notice the design of a plane's nose? does it strike you that it is designed that way to trap air? to cause friction? to try and push all the air around it along?

Of course not.

The idea for a plane to work is that the air around it is still (i.e. moving relative to the zooming plane) meaning that, relative to the wing surfaces, which provide the lift (I hope that point is gradually sinking in).

Without wings your jet will just go ballistic, maybe tumbling a bit when it encounters turbulence, but will never soar into the air like so many WINGED objects do every day out of Heathrow, JFK etc.

Your friend's flash presentation implies that if you put a wheeled object on a moving surface the wheels will rotate and the object will remain at rest - this simply is not true.

 

[User Name]

http://img310.imageshack.us/my.php?image=airplane2nx.swf

That only works if the wheels are frictionless! That's what I came up with earlier. The plane has to move the wheels foward before it can too. Since the runway is always moving the same speed as the wheels, just in the opposite direction, the plane can't push them forward. So they stay put, and so does the plane.

 

[Xendance]

But what if the turbines are ****ing the air so fast that it will generate a strong wind that will lift the plane?

 

[[CoR]MiccyNarc]

http://www.straightdope.com/columns/060303.html

Why is the air around the plane moving at 400 mph? tractor fields? magic? Ever notice the design of a plane's nose? does it strike you that it is designed that way to trap air? to cause friction? to try and push all the air around it along?

Of course not.

The idea for a plane to work is that the air around it is still (i.e. moving relative to the zooming plane) meaning that, relative to the wing surfaces, which provide the lift (I hope that point is gradually sinking in).

Without wings your jet will just go ballistic, maybe tumbling a bit when it encounters turbulence, but will never soar into the air like so many WINGED objects do every day out of Heathrow, JFK etc.

Yes, it 's all designed to allow airflow. Notice that it has nothing to do with the ground.
Perform the car on the treadmill experiment, now. Don't come back until you have.

The airplane uses its engines to push the air, causing acceleration. That's why they make that big "WHOOSH"'ing sound that you may have noticed. The wheels just provide a relatively frictionless surface to move on. That is all.

The plane has to move the wheels foward before it can too.

No it doesn't. The plane moves, causing the wheels to move (that whole Newtonian equal and opposite reaction bit).

 

[Cuddles]

But if there was a wind making machine can the plane fly then?(i kno its a stupid question)

 

[[CoR]MiccyNarc]

But if there was a wind making machine can the plane fly then?(i kno its a stupid question)

Guess what! The engines = wind making machine! Since they cause the airplane to move relative to the air around it thereby creating wind, and LIFT!

So yes, there is a windmaking machine involved in this scenario.

 

[[CoR]MiccyNarc]

Everyone read this post since moz editted it with some useful info:
http://www.redorchestragame.com/forum/showpost.php?p=245871&postcount=61


Also, you all shot yourselves in the foot:
If the plane is not moving, the conveyer belt won't be moving. Therefore, the plane has to be moving, relative to the wind (that's how you measure an airplanes speed, relative to the windflow across sensors), therefore, the plane, according to your logic, has to be accelerating and therefore taking off. QED by your own logic.

 

[Moz]

In this case however, the jet's thrust is being neutralized by the mill. The jet is moving forward. The runway is moving backward at the SAME speed. The plane can not out accelerate it because if the plane moves at 400 MPH. The treadmill is going 400 MPH in the opposite direction. All the plane can do is keep up with the treadmill. The wheels do affect the plane because they are attached to it. If they can't move forward because the runway is keeping them stationary. The plane can't either because it is being held in place by the wheels.

That is the dumbest thing I've heard all day,

Kill yourself

 

[Cuddles]

Yea but the engines dont generate lift under the wings (i think) they only push the plane forward (in my world? maby?) Am I right or am i a redneck?

 

[[CoR]MiccyNarc]

Yea but the engines dont generate lift under the wings (i think) they only push the plane forward (in my world? maby?) Am I right or am i a redneck?

You are completely right! Give yourself a prize! They push the plane forward, causing air to flow past the wings generating lift!

Moz, you're my hero.

 

[User Name]

http://www.straightdope.com/columns/060303.html

Yes, it 's all designed to allow airflow. Notice that it has nothing to do with the ground.
Perform the car on the treadmill experiment, now. Don't come back until you have.

The airplane uses its engines to push the air, causing acceleration. That's why they make that big "WHOOSH"'ing sound that you may have noticed. The wheels just provide a relatively frictionless surface to move on. That is all.




No it doesn't. The plane moves, causing the wheels to move (that whole Newtonian equal and opposite reaction bit).

The wheels are a part of the plane. The plane is pushing the wheels forward, but the runway is moving backward at exactly the same speed. All the plane is doing is keeping the wheels stationary in relation to everything around it. If you had a jet car, on the treadmill,and the treadmil could accelerate at exactly the same speed as the jet car. The jet car would remain stationary. Since the treadmill is moving exactly the same speed as the car, just in the opposite direction, it never moves. It stays right where it is, because it's push, is being neutralized by the treadmills pull. The same is true for the jet plane. The push of the jet's engines is being neutralized by the pull of the treadmill. So it stays right where it is.

 

[Cuddles]

Everyone read this post since moz editted it with some useful info:
http://www.redorchestragame.com/forum/showpost.php?p=245871&postcount=61


Also, you all shot yourselves in the foot:
If the plane is not moving, the conveyer belt won't be moving. Therefore, the plane has to be moving, relative to the wind (that's how you measure an airplanes speed, relative to the windflow across sensors), therefore, the plane, according to your logic, has to be accelerating and therefore taking off. QED by your own logic.

That was such a long post i just read the last sentance

 

[Cuddles]

You are completely right! Give yourself a prize! They push the plane forward, causing air to flow past the wings generating lift!

Moz, you're my hero.

But most jets have the engines under the wing and some have them in the tail.

 

[Tak]

No it wouldn't. The turbines are moving air, sure, but not over the wings. They're only providing forward thrust. The key is the over the wings part. The airspeed over the wings is the same if the plane is sitting there or if it's on that magical treadmill at full throttle.

Think of it like this. If you are in a car on one of those roller-bay things (don't know what they're called, sorry) where there are rollers under the wheels so the car doesn't move, you can press the accelerator as hard as you want, and still open the door with ease. Because there is no force from the wind. If you go down the freeway as fast as you can, you have to fight against the wind to open the door.


Having a lot of forward motion cancelled out by motion in the opposite direction results in no movement. No movement means no wind going over/under the wings, no lift.


Now, if there was an equally magical fan in front of the whole thing that always acted above the thrust provided by the engines, it would be possible to make the plane 'take off' tot he extent that a skilled pilot could possibly keep it 'not moving', but that would take HUGE machines. It would be like flying a model airplane in a wind tunnel. If you can get the right balance of forces, you can effectively make a plane 'hover', but it would take a lot to do that with what looks like a Boeing as in that picture
​

 

[Cuddles]

No it wouldn't. The turbines are moving air, sure, but not over the wings. They're only providing forward thrust. The key is the over the wings part. The airspeed over the wings is the same if the plane is sitting there or if it's on that magical treadmill at full throttle.

Think of it like this. If you are in a car on one of those roller-bay things (don't know what they're called, sorry) where there are rollers under the wheels so the car doesn't move, you can press the accelerator as hard as you want, and still open the door with ease. Because there is no force from the wind. If you go down the freeway as fast as you can, you have to fight against the wind to open the door.


Having a lot of forward motion cancelled out by motion in the opposite direction results in no movement. No movement means no wind going over/under the wings, no lift.


Now, if there was an equally magical fan in front of the whole thing that always acted above the thrust provided by the engines, it would be possible to make the plane 'take off' tot he extent that a skilled pilot could possibly keep it 'not moving', but that would take HUGE machines. It would be like flying a model airplane in a wind tunnel. If you can get the right balance of forces, you can effectively make a plane 'hover', but it would take a lot to do that with what looks like a Boeing as in that picture
​

Thats what i wanted to say.

 

[Moz]

ENGINES DON'T MATTER.

YOU COULD HAVE A FAT PERSON PUSHING, OR ROLL IT DOWN A HILL.

THE ONLYING THINGS THAT ARE REQUIRED TO CREATE LIFT:

AIRFOIL (wings)

AIRFLOW OVER SAID AIRFOIL (wings)

Then what are engines for?

If the plane moves forward, the air goes over wings, lift is generated, the faster it goes, the more lift (there is a complicated curve that is different for every airfoil shape) Once the lift created is higher than the weight, the plane moves up and flies away! (weeeee!)

Thrust is anything that pushes the plane forward creating airflow. Engines, jets, rockets, your arm, superman, gravity, another plane with a rope...

Drag is what acts against the plane's forward flight, wind caused friction, (skin, parasite, form and one caused by lift: induced) This increases with increases with thrust and lift (induced) and thats why you need to keep providing thrust (from engines) to counter act this or you will stop travelling forward in the airflow.
If drag is greater than thrust, the plane slows.

If you took a big fan and stuck an airplane in it, the plane could fly without moving forward in relation to the ground, but would actually be going forward in the air.

 

[Ruprecht]

...

its so simple i cant even image why the people wont understand it, just grab a pencil and paper and write it down in numbers.

the mill doesnt have any effect on the planes speed,when it goes with 400km/h, it goes with 400km/h.

all the mill causes is that the weels will spin twice as fast and that, however, doesnt have any effect on the planes speed.