23 Oct 06
Originally posted by skeeterWrong.
The 'pressure thing' that I refer to is the only 'thing' that enables a plane to fly. That pressure is created by the differing rates of flow over the two surfaces. Air flow over the longer surface, the top, is faster so less pressure whilst the flow over the shorter is relatively slower therefore more pressure and that is what produces the lift. Nothing else does.
skeeter
Have a look at:
http://en.wikipedia.org/wiki/Lift_%28force%29
http://en.wikipedia.org/wiki/Wing
http://en.wikipedia.org/wiki/Angle_of_attack
and
http://en.wikipedia.org/wiki/Airfoil
You'll find the statement you made in the misconception section of the Lift page.
23 Oct 06
Originally posted by XanthosNZ
Wrong.
Have a look at:
http://en.wikipedia.org/wiki/Lift_%28force%29
http://en.wikipedia.org/wiki/Wing
http://en.wikipedia.org/wiki/Angle_of_attack
and
http://en.wikipedia.org/wiki/Airfoil
You'll find the statement you made in the misconception section of the Lift page.
I agree, you're wrong, there is more lift created over the top of the wing than there is at underneath.
23 Oct 06
Originally posted by flyUnityNo. And ATY has answered correctly (see the 2nd post).
A plane is standing on a runway that can move (some sort of treadmill). The plane moves in one direction, while the conveyer moves at the same speed but in the opposite direction. Can the plane take off?"
(copied and pasted from another source)
Other answers I've read on this thread (that no agree with ATY post) only puts in evidence your poor understanding -if any- of elementary physics laws, not to speak of fluid mechanics.
23 Oct 06
1 edit
Originally posted by CrazyLilTingPlanes create forward motion by pushing on the air (which is stationary) and the wheels freely rotate (they aren't driving, they could easily be replaced with skids [and are in some planes]).
No. And ATY has answered correctly (see the 2nd post).
Other answers I've read on this thread (that no agree with ATY post) only puts in evidence your poor understanding -if any- of elementary physics laws, not to speak of fluid mechanics.
So normally a plane takes off by pushing on the air to create forward motion until it reaches a certain speed at which it takes off due to created lift.
On a treadmill the plane pushes on the air and changes from moving backwards through the air to being stationary to it to moving forward through it. The plane is decoupled from the treadmill by the freely rotating wheels. As the plane starts to move forward the wheels will be spinning faster than the plane is moving but that isn't an issue. And so the plane again takes off when forward motion creates lift.
EDIT: Note that ATY has admitted that his first post was wrong.
23 Oct 06
1 edit
Originally posted by XanthosNZHi Xanthos,
Planes create forward motion by pushing on the air (which is stationary) and the wheels freely rotate (they aren't driving, they could easily be replaced with skids [and are in some planes]).
So normally a plane takes off by pushing on the air to create forward motion until it reaches a certain speed at which it takes off due to created lift.
On a tr orward motion creates lift.
EDIT: Note that ATY has admitted that his first post was wrong.
I've don't read all the posts.
But only common sense dictates that if an airplane is trying to take off while being on a conveyer that takes it at 0 velocity measured with respect to the atmosphere,- which is the case formulated in the original question (may be I have misunderstood it)- it will never take off.
Edit: as long as the conveyer keep the airplane at velociry 0.
23 Oct 06
Originally posted by CrazyLilTingHow would the conveyor belt keep the plane at 0 velocity with respect to the atmosphere?
Hi Xanthos,
I've don't read all the posts.
But only common sense dictates that if an airplane is trying to take off while being on a conveyer that takes it at 0 velocity measured with respect to the atmosphere,- which is the case formulated in the original question (may be I have misunderstood it)- it will never take off.
Edit: as long as the conveyer keep the airplane at velociry 0.
24 Oct 06
Originally posted by XanthosNZEasy. Imagine no wind velocity, may be only a mild breeze.
How would the conveyor belt keep the plane at 0 velocity with respect to the atmosphere?
In ideal conditions, the velocity of air being 0 measured to the conveyor.
As far as the relative velocity of the airplane remains 0, so does the airplane (velociry) to the atmosphere.
If that numbers aren't exact, may be the plane could take off... But I can't imagine me driving an airplane in such conitiions, when the tale off is finite (in mathematical and practical tems 🙂 )
24 Oct 06
Originally posted by CrazyLilTingYou have actually made no sense at all.
Easy. Imagine no wind velocity, may be only a mild breeze.
In ideal conditions, the velocity of air being 0 measured to the conveyor.
As far as the relative velocity of the airplane remains 0, so does the airplane (velociry) to the atmosphere.
If that numbers aren't exact, may be the plane could take off... But I can't imagine me driving an airplane in such conitiions, when the tale off is finite (in mathematical and practical tems 🙂 )
PS. Reading threads before posting in them is advised.
24 Oct 06
Originally posted by CrazyLilTingSo let's analyse your post.
My "broken english" is by no way a trouble to make sense of my posts. At least for you. Go ahead, and make your point, if you have one 🙂
"Easy. Imagine no wind velocity, may be only a mild breeze.
In ideal conditions, the velocity of air being 0 measured to the conveyor. "
So there isn't any wind. Fine.
"As far as the relative velocity of the airplane remains 0, so does the airplane (velociry) to the atmosphere."
You can't say relative velocity without giving what it is relative to (as you did in the first phrase). It's meaningless if you do.
"If that numbers aren't exact, may be the plane could take off... But I can't imagine me driving an airplane in such conitiions, when the tale off is finite (in mathematical and practical tems )"
What tail-off? What are you talking about?
So even if I assume you mean that the plane cannot gain velocity relative to the air you'd still be wrong as that isn't true.
24 Oct 06
Originally posted by XanthosNZNone of this really contradicts the statement that it is the pressure difference that causes lift. The misconceptions are about exactly what causes that pressure difference. But there's still a pressure difference.
Wrong.
Have a look at:
http://en.wikipedia.org/wiki/Lift_%28force%29
http://en.wikipedia.org/wiki/Wing
http://en.wikipedia.org/wiki/Angle_of_attack
and
http://en.wikipedia.org/wiki/Airfoil
You'll find the statement you made in the misconception section of the Lift page.
24 Oct 06
2 edits
So, someone give a straight yes or no answer to the question!
A plane is at point X on the runway. The runway begins to move left. The plane begins to move right at exactly the same speed as the runway. Therefore the plane is stationary at point X all the time.
Can someone therefore explain how a plane is supposed to lift off the ground if it isn't moving?