visualisation of the lift distribution over a wing

In article ,
cavelamb wrote:

Alan Baker wrote:
In article ,
brian whatcott wrote:

Alan Baker wrote:
/snip/
Any change in pressure is *by definition* a change in the number of
particles in the fluid that are impacting the surface.
That assertion is incorrect. You are no dummy so I'm sure you'll
correct
it when you realize the errors.
Sorry, but it's not. Pressure is created by particle collisions.
Hmmm...looks like Jim expected too much from you: the kinetic theory of
gases has it that pressure may be computed from the temperature AND the
density of gases... that is to say, by retaining the SAME molar quantity
of gas, and raising its temperature (which translates to a higher
velocity), the pressure is increased P.V = R.t and all that....

Put it another way: each "hotter" molecule reverses direction at a
surface with greater force.

Brian W
I'm perfectly aware of that...
It took me too long to realise the problem: you have a problem with
saying: "Oh yes, I got it worng."

I didn't get anything wrong.

I am and was perfectly aware of the fact that the temperature of a gas
indicates a different average speed for the gas molecules and thus a
different momentum when the strike a surface.

People who WON'T do that in technical discussions qualify as people who
are just happy to stir up heated debate.

I agree. What of it.

I am going to leave this thread now: wrasslin' with pigs gets the
hands jest too soiled...

You can go.


I feel the same as Brian.
This had not been a discussion as much as a troll.

OF BLOODY COURSE, the high pressure area under the wing pushes up.
So what.

It couldn't possibly do that without the reduction of pressure on the top.
That's where all the magic is.

And you, sir, are a bloody bore.

So now, please also dismiss me.

Look, I started out to clarify the point for those who have the wrong
perception of the situation...

....and it turned that there were such people.

I explicitly stated that if the OP meant that the low pressure above the
wing is responsible for two thirds of the pressure *difference* then he
was on solid ground (while allowing as how I didn't know what the
precise figures actually were).

Ever since then, types like you have been coming in and saying "IT
DOESN'T MATTER", when very clearly (because there are people who don't
understand the situation) it does.

It's like the downwash argument. You can say "IT DOESN'T MATTER", when
people argue that the air behind an aircraft is not deflected downward,
but it *does* matter. Having an accurate understanding of the physical
processes of flight matters.

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg

Alan Baker wrote:

It's like the downwash argument. You can say "IT DOESN'T MATTER", when
people argue that the air behind an aircraft is not deflected downward,
but it *does* matter. Having an accurate understanding of the physical
processes of flight matters.

It isn't really deflected downward, not for long anyway. It's churning
in a torus. Like a smoke ring.

In article ,
Beryl wrote:

Alan Baker wrote:

It's like the downwash argument. You can say "IT DOESN'T MATTER", when
people argue that the air behind an aircraft is not deflected downward,
but it *does* matter. Having an accurate understanding of the physical
processes of flight matters.

It isn't really deflected downward, not for long anyway. It's churning
in a torus. Like a smoke ring.

No.

It really *is* deflected downward.


The edges of the deflected area churn, and the air that is deflected
ends up getting diffused among all the other air below *it*, but it
really is deflected downward.

And eventually, that downward deflection makes it way until it -- very
diffusely -- impacts upon the surface of the earth. That is the only
thing that finally stops it.

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg

Alan Baker schreef:

No.

Yawn.

Alan Baker wrote:
In article ,
Beryl wrote:

Alan Baker wrote:
It's like the downwash argument. You can say "IT DOESN'T MATTER", when
people argue that the air behind an aircraft is not deflected downward,
but it *does* matter. Having an accurate understanding of the physical
processes of flight matters.
It isn't really deflected downward, not for long anyway. It's churning
in a torus. Like a smoke ring.

No.

It really *is* deflected downward.


The edges of the deflected area churn, and the air that is deflected
ends up getting diffused among all the other air below *it*, but it
really is deflected downward.

And eventually, that downward deflection makes it way until it -- very
diffusely -- impacts upon the surface of the earth. That is the only
thing that finally stops it.

After more than 100 years of flight, the atmosphere still hasn't been
pushed down to the earth's surface.

Ok, so there is a low pressure field above the wing,
and the wing is pressed up from underneath.

So, just out of curiosity, what happens to the air
that was in the low pressure field above the wing -
after the wing passes?

Does it just magically co back to it's old ways
(and places)?

And the air that was in the high pressure field under
the wing?

After the wing passes, is it unaffected as well?

cavelamb wrote:
Ok, so there is a low pressure field above the wing,
and the wing is pressed up from underneath.

So, just out of curiosity, what happens to the air
that was in the low pressure field above the wing -
after the wing passes?

Does it just magically co back to it's old ways
(and places)?

And the air that was in the high pressure field under
the wing?

After the wing passes, is it unaffected as well?

It's all a slowly descending smoke ring. If the earth was "the only
thing that finally stops it" as Alan says, none of the ring's energy
would be lost as it pushes through the surrounding air to reach the earth.

http://www.av8n.com/how/htm/airfoils.html#sec-circulation-vortices
Figure 3.27 ties the wingtip vortices in with the rest of the
circulation pattern, showing the whole smoke ring in red.

Also look up at section Section 3.11,
http://www.av8n.com/how/htm/airfoils.html#sec-spinners
Add the Fluttering Card circulation, Figure 3.25, to familiar tip
vortices, and you get the whole ring.

Other articles do a nice job explaining tip vortices or downwash behind
the wing as isolated subjects, but that's where they end their stories.

Beryl wrote:
cavelamb wrote:
Ok, so there is a low pressure field above the wing,
and the wing is pressed up from underneath.

So, just out of curiosity, what happens to the air
that was in the low pressure field above the wing -
after the wing passes?

Does it just magically co back to it's old ways
(and places)?

And the air that was in the high pressure field under
the wing?

After the wing passes, is it unaffected as well?

It's all a slowly descending smoke ring. If the earth was "the only
thing that finally stops it" as Alan says, none of the ring's energy
would be lost as it pushes through the surrounding air to reach the earth.

http://www.av8n.com/how/htm/airfoils.html#sec-circulation-vortices
Figure 3.27 ties the wingtip vortices in with the rest of the
circulation pattern, showing the whole smoke ring in red.

Also look up at section Section 3.11,
http://www.av8n.com/how/htm/airfoils.html#sec-spinners
Add the Fluttering Card circulation, Figure 3.25, to familiar tip
vortices, and you get the whole ring.

Other articles do a nice job explaining tip vortices or downwash behind
the wing as isolated subjects, but that's where they end their stories.


I've seen the results first hand.

Flying along just above a smooth cloud surface at high subsonic,
the "wake" behind the leader makes a shallow trough in the cloud,
then the edges swirl back up into the tip vortices.

The high pressure air underneath rebounds up, and the low pressure
field above the wing rebounds back down.

Net result = zero.

In article ,
Beryl wrote:

Alan Baker wrote:
In article ,
Beryl wrote:

Alan Baker wrote:
It's like the downwash argument. You can say "IT DOESN'T MATTER", when
people argue that the air behind an aircraft is not deflected downward,
but it *does* matter. Having an accurate understanding of the physical
processes of flight matters.
It isn't really deflected downward, not for long anyway. It's churning
in a torus. Like a smoke ring.

No.

It really *is* deflected downward.


The edges of the deflected area churn, and the air that is deflected
ends up getting diffused among all the other air below *it*, but it
really is deflected downward.

And eventually, that downward deflection makes it way until it -- very
diffusely -- impacts upon the surface of the earth. That is the only
thing that finally stops it.

After more than 100 years of flight, the atmosphere still hasn't been
pushed down to the earth's surface.

Sorry, Beryl, but you're just wrong.

--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg

Alan Baker wrote:
In article ,
Beryl wrote:

Alan Baker wrote:
In article ,
Beryl wrote:

Alan Baker wrote:
It's like the downwash argument. You can say "IT DOESN'T MATTER", when
people argue that the air behind an aircraft is not deflected downward,
but it *does* matter. Having an accurate understanding of the physical
processes of flight matters.
It isn't really deflected downward, not for long anyway. It's churning
in a torus. Like a smoke ring.
No.

It really *is* deflected downward.


The edges of the deflected area churn, and the air that is deflected
ends up getting diffused among all the other air below *it*, but it
really is deflected downward.

And eventually, that downward deflection makes it way until it -- very
diffusely -- impacts upon the surface of the earth. That is the only
thing that finally stops it.
After more than 100 years of flight, the atmosphere still hasn't been
pushed down to the earth's surface.

Sorry, Beryl, but you're just wrong.

As I said, the atmosphere isn't getting any shorter. Do you disagree
with that?
Repeating that "the net flow is downward" isn't making progress.