Would a plane take off on a tredmill?

[SN2BH22CB7]

http://www.youtube.com/watch?v=c99ZHZw97rU

Here is an airplane taking off with a headwind. Notice how slow his "groundspeed" (speed over the ground) is. Also notice that you can hear a strong wind in the camera mic.

The only thing that matters is the speed of the airflow around the wing. If that airflow can be achieved at ZERO speed over the ground, then the airplane will lift off.

Here are two flightsim videos to demonstrate, no they are not real airplanes, but the physics are real, and you just don't seem many videos of this, because it isn't done alot in real life for safety reasons. But it is possible.

http://www.youtube.com/watch?v=PpptCqy4suQ

http://www.youtube.com/watch?v=6bdgeAN4DQ8

The first is a 747 doing a vertical takeoff.

The second is a Cessna flying backwards.

I have friends who have successfully flown an airplane at 0 speed over the ground, because the winds were strong enough to allow it.

1) This is why we always try to takeoff directly into the wind. The wind creates airflow over the wings, and thus reduces the amount that we have to accelerate to takeoff. This shortens the takeoff distance. In theory, it would be perfectly possible to takeoff with no ground roll.

It is all about the AIRSPEED at which an airplane's wing generates sufficient lift to counter the weight of the airplane.

http://www.youtube.com/watch?v=eQChoy6mogA

http://www.youtube.com/watch?v=1a44e7bm2yw

http://www.youtube.com/watch?v=SI4JnyphGQM

The same rules that apply to small airplanes, also apply equally to large ones, and vice versa.

end result...you still need air under the wings....( what I have been saying all along )

[owequitit]

so you mean to tell me...without AIR under the wings...it will take off?



I strongly DISAGREE with you THIS TIME Scott my friend!

you NEED air under the wings in order for LIFT!

if you claim you're a pilot...then you should know that!



if order for the plane to get off the ground..you need a substantial amount of airflow under the wings in order for LIFT..

in order for forward propulsion...you need the turbines...( forward movement )

the only aircrafts I know that will hover are the Harrier and choppers.

( doesn't need forward propulsion for takeoff ) why..they force air down to the ground for lift )

You can disagree all you want. What you have is a basic misunderstanding of the variables of how an airplane flies, and how those variables inter-relate to other variables.

1) You have a basic misunderstanding of how lift works, so I am not sure how your deep grasp of all other things flying related can be bulletproof.

Here goes.

2)Lift is produced when air flows OVER a wing. That is why the top surface of a wing has curvature to it. As the air flows over the wing, it creates a low pressure area, since it must flow at a greater airspeed. This is the same as a venturi in a carburetor, and is dictated by Bernoulli's priniciple. The top half of a wing is essentially 1/2 of a venturi.

As the air flows over the wing, and creates lower pressure, the air that travels under the wing remains at approximately the same pressure. That means that we now have a pressure differential with high pressure below the wing, and low pressure above. Since pressures tend to want to equalize, this results in a lifting force on the wing.

But wait, there's more.

3)Since all objects in motion tend to want to stay in motion (Newton's Law of Intertia) the air that has been forced to flow over the top of the wing, has inertia. This creates a differential of forces more specific than just high pressure on the bottom and low pressure on top. Following, is the part that is important to this discussion. The air that flows over the wing has inertia, and wants to flow backward and downward (and indeed does) towards the ground, when it leaves the trailing edge of the wing. This is known as downwash.

But wait, there is more.

4)Since Newton's Laws also state that for every action, there is an equal and opposite reaction, this large mass of air that is now flowing backward and downward off the wing, creates a very strong foward and upward reaction on the wing, which in turn creates lift.

5)It is a combination of these two factors, which essentially create a large volume of air circulation, that allows an airplane to fly.

6)Now, pay attention to the explanation above. Notice that at no time was there a mention of groundspeed. The only factor that dictates whether or not a wing produces enough lift to fly is the velocity and amount of airflow around that wing. Speed over the ground has nothing to do with it. Air is a fluid that moves independently of the ground, and since the wing relies on AIR to create lift, it's production of lift is also independent of the ground.

This is why airplanes are flown at AIRSPEEDS and not GROUNDSPEEDS. The speed of the air flowing over the airplane is independent of the airplane's speed over the ground.

Now, lets apply this to something you know. Wind. What happens when the wind is strong? It causes air to flow around your body. Same thing with a wing. If the wing is oriented so that the wind blows straight from front to back, that wing will start to produce lift, even if the airplane is not moving over the ground. Period.

The opposite applies to an airplane with a wind coming from behind. The airplane will have to roll longer to create enough airflow in the proper direction, to allow the wing to produce enough lift to get the airplane in the air.

7)This is why a helicopter can lift off vertically. The rotor blades are wings, and by spinning them really fast in a circle, we generate the lift, without the aircraft moving foward, because even though the aircraft is stationary, the rotor blades have a very large amount of air flowing over them, allowing them to produce lift, and thus allowing them to lift the stationary helicopter off the ground.

8)An airplane WILL take off with ZERO groundspeed, given a strong enough headwind (the airplane is aligned into the wind, like a wind indicator, and the airflow is flowing straight from the front to the back of the airplane). The airplane is perfectly capable of this. ANY conventional airplane is capable of this, even a fully loaded 747, IF and ONLY IF the WIND velocity is high enough.

The problem is that it creates severe safety hazards when the airplane is aligned any other way but into the wind, i.e. while taxiing or parked, so during conditions like this, we typically tie the planes up and sit around and talk.

9)So what is the solution, that allows us to fly safely, and also allows us to fly independent of what the wind is doing (i.e. we can still take off with no wind)? A take off roll. This allows a conventional airplane to create enough airflow OVER the wing, to allow us to fly. Believe me or not, but a headwind WILL decrease the distance you have to roll in order to fly. Why? Because that additional airflow is helping the air circulate around the wing, thus reducing the speed the airplane needs to be at in order to produce enough lift to fly. This concept relates equally to large airplanes as small ones.

10)Ultimately, lift produces a force that counteracts gravity and allows an airplane to move opposite the direction of gravity.

A harrier achieves this because it has more power than weight, when lightly loaded, and thus can rise against gravity on engine power alone, even though the wing is not producing any lift at all. It is also why a Harrier must slowly transition to foward flight, gradually trading vertical thrust for horizontal thrust and getting the wing to produce lift.

If you have understood what I have said so far, then it should become a logical conclusion that the free rolling wheels on an airplane don't stop it from moving, and that the ground has nothing to do with lift.

That means that when we add takeoff power, the airplane accelerates foward, the wing begins to produce lift, and the airplane takes off. It DOES NOT matter what the ground under the wheels is doing, and it does not matter how fast the wheels are turning. It does not matter how fast the airplane is travelling over the ground. All that matters is that the wings are producing enough lift to fly, and that is dictated SOLELY by the velocity of the air flowing over the wing. Everything else is inconsequential, and doesn't have any effect at all.

Period.

I took some time to do some searching for you:

These are both links to How Stuff Works. They have good diagrams and basic explantions.

http://travel.howstuffworks.com/search.php

http://travel.howstuffworks.com/airplane.htm

These are the links to the main 2 FAA books used in initial flight training. They are a little more in depth, and have several levels of understanding in them, starting with basic. These are in PDF format, although if you would like to get ahold of them in print, let me know, and I would be happy to provide you with the appropriate FAA Document numbers.

http://www.faa.gov/library/manuals/a...lane_handbook/

http://www.faa.gov/library/manuals/a...ilot_handbook/

This book is much more in depth, and has all you would ever need to know about aerodynamics. Everything beyond this book is engineering level, and even most engineers will refer to this book first if they have a question.

http://www.amazon.com/Aerodynamics-N.../dp/156027140X

I have anywhere from 30-50 more technical textbooks on how airplanes fly, so let me know if this doesn't satisfy you.

P.S. I also forgot to mention that I have degree in this stuff in addition to my ratings.

[owequitit]

end result...you still need air under the wings....( what I have been saying all along )

That is correct. But the flow of air OVER the wings has nothing to do with the ground. And that is where you are 100% wrong.

Thus the airplane will fly no matter what the treadmill does.

The question was never whether a wing needs lift to fly, it is whether or not it would takeoff on a treadmill, and the answer is YES.

[sulimed]

if the treadmill can match the planes top volcity (on the ground)
then NO

but if the treadmill only match's the planes taxiing (sp) speed.
it mite be possible

[MikeW]

I didnt have time to read all 4 pages, but what about Mythbusters...

Anybody trust them to test this or at least give it a try??

Id like to see their take on it as well.

[accordaffair]

if the treadmill can match the planes top volcity (on the ground)
then NO

but if the treadmill only match's the planes taxiing (sp) speed.
it mite be possible

You sure about that?

[203Cree]

The Greatest post in the history of the interwebs.

I love you in the non *** way a man can love another man.

Epic. FUCKING EPIC!

Seriously people, how is this concept so hard to grasp?

Maybe this simplistic video will help explain it to you lemmings....

CLICK ME FOR LEMMING VID

Can we all just STFU about this now till Mythbusters comes on? FUCK!

[owequitit]

I love you in the non *** way a man can love another man.

Epic. FUCKING EPIC!

Seriously people, how is this concept so hard to grasp?

Maybe this simplistic video will help explain it to you lemmings....

CLICK ME FOR LEMMING VID

Can we all just STFU about this now till Mythbusters comes on? FUCK!

LOL! That will work too, except that matchbox car might need some new wheel bearings!

[owequitit]

if the treadmill can match the planes top volcity (on the ground)
then NO

but if the treadmill only match's the planes taxiing (sp) speed.
it mite be possible

I think you should read my last post...

[ChIoVnIdCa]

why is this post still here

[owequitit]

I didnt have time to read all 4 pages, but what about Mythbusters...

Anybody trust them to test this or at least give it a try??

Id like to see their take on it as well.

I trust them to do it, because there is only one outcome. The airplane will fly. See 203cree's video posted above.

The only difference is that an actual airplane would simply continue to accelerate until takeoff speed, and would then takeoff and clear the runway.

[4CYLPOWER92]

I agree with Pilot owequitit 100%, and would like to add that the only thing the treadmill would do is cause the wheels to spin twice as fast, having nothing to do with anything.

[MikeW]

But why would the wheels moving have anything to do with lift

Now if you had equivalent air being fed at the plane, at speed, yes, i think it would take off, but if you just sat it in a field and basically lifted it off the ground and acceleratted the engines, no i dont think it would take off.

Someone back me up or correct me anywhere they feel necesarry, but engines really wouldnt have anything to with this. Isnt it sheer wind velocity over the wings, causing lift??

I mean, if you could find a cliff high enough, could you, essentially, push a passenger 747, off that cliff and assuming winf velocity/sheeras were in proper order, etc etc, couldnt that plane, being piloted to do so, essentially, get lift??

Maybe not enough to get it up and away from the ground, but i mean at least enough to get it leveled out???

Thats how gliders work. Essentially. The only reason theyre flown to high alt's is so that they can get plenty of airtime. Scale it down. A model, styrofoam plane works the same way. Its small size only requires a small amount of resistance to gain lift. granted it isnt much, but it doesnt have engines. Shit, same rule even applies to paper planes. You give anything a wing that is proportionate to its body and it can, essentially, have lift. Not flight, "LIFT". I know, humans have tried it, and although they havent exactly soared across the sky, you could still "lower" or "float". You're still getting enough resistance to at least, slow gravity's pull...

Back to the subject at hand....feed the proper air flow at the plane, on the treadmill, or even w/o the treadmill, and i think it could get lift. I mean, it may be unheard of, but feed enough wind, head-on, at an airplane, and it could get off the ground. I dunno that its gonna go anywhere, but the formula still stands; get enough air moving over/under the wing of an airplane, and you have lift.

I think the real catch here is the engines. Im sure we could all come to agree that with enough airflow, the airplane will get lift. Not flight, but lift.

Now of you powered up engines to full speed.....there inlies the problem.

If the winf gust was so striong that it did indeed get the plane off the ground:
A) How far off the ground would the plane have to be for the engines to provide enough power to get it going in a forward and up direction?

B) If the engines provided enough power, in time, would the airplane "hover" then begin its forward ascent, or would the airplane need to be pointed in an "upward" direction?

Does anybody else think that this test could be done by simply dropping, or pulling a plane, behind another, powering up engines, then being released???

Wouldnt the principals still stand?? Gravity wuld be pulling it in a downward directiom, but power up engines, and drop it at about 40k feet...i think thats plausible.

So....runway, little to no wind, NO. Engines or not. Without proper airflow, the wheeld could spin and spin, but it aint going anywhere.

Feed it the proper airflow, yes, it could acheive LIFT. It might be an un-controlable lift, but nonetheless, LIFT.

Power up engines, give it such a gust of air that the plane gets "lifted" 100's of feet in the air...engine at full throttle...plausible.

Drop it from a substantially high distance, again, engines Full Throttle...I think, Plausible, even do-able.

[LinX]

When it is sitting on the conveyor belt, it is not moving through the air. No matter how fast the plane (and belt) move, it will still remain in the same position, and thus not move through the air.

This is where your calculation falls askew. Think of the wheels as not powered at all but dummys attached to the plane. When landing, a plane slows down not by braking in mid air but by lowering the amount of thrust generated by its turbines.

[MikeW]

although moving downward, its forward motion, in a downward direction causes it to slow as well. Once it reaches the ground, brakes and instilling "flaps-up" (causing downward pressure on the plane) slows it.