Backwash Causes Lift?

Le Chaud Lapin wrote in
ups.com:

On Oct 7, 11:54 am, flightoffancy wrote:
JC, you're confusing yourself.

Instead of focusing on "fixed" wing, think for a moment about
helicopter
blades and propellers. These are airfoils not fundamentally different
than one attached to the side of an aircraft.

Agree.

Anyone who has ever seen video of a helicopter hovering or has been
near
a helicopter hovering knows that air is being pushed down by the
blades
with massive force and that is the equal and opposite force exerted
by
the mass of air on the bottom of the blades that keeps the helicopter
from falling out of the sky.

More agreement.

A fixed wing aircraft is only different in that it pushes air under
it
by moving forward, rather than in a circle.

Even more agreement.

The bottom line is simple: an airplane can only stay aloft by pushing
air down.

Still even more.

Yes, the angle of attack gives the greater impulse to knock the air
downward. But a curved upper surface gives even more downard force to
the air.

Still even more.

Nit-picking Jeppensen's watered down description, which was not
authored
for aeronautical engineers (which I note you are NOT), will not
advance
your piloting skills in any significant way.

There is one small problem with your exposition:

You are referring to the bottom of the wing.

Jeppesen is talking about the top of the wing.


You're an idiot.


Bertie

Mxsmanic wrote in
:

Le Chaud Lapin writes:

This true and not true. A wing does not necessarily have to push air
downward to cause lift.

Not correct.


Yes, it is, fjukkwit


Bertie

flightoffancy wrote in
:

In article ,
says...
When in straight and level flight, the air flow through the rotor blades
of a gyrocopter is upward.


Yeah well there's a lot of empty space between those gyrocopter blades
for the air to blow through in an upward direction.

What you don't mention is that there's also downward component to that
airflow, when it impacts the gyrocopter blades and is knocked downward.
The air gets knocked downard, the blades get knocked upward, the
gyrocopter is attached to the blades, it gets held up in the air -- so
the magic is revealed once again as "downwash".


Nope


Bertie

Mxsmanic wrote in
:

flightoffancy writes:

I don't deny those facts; but the greater the curve of the wing the
more the air pushes down behind the wing.

If that were so, then an airfoil with a half-circle for a
cross-section would produce enormous lift. In fact, this isn't the
case.


Actually, yes it is.

Fjukkwit



Notice the smoke flow in the photo I link to below:

http://www.aa.washington.edu/uwal/uw.../tech%20guide%
20pics/smokeflowvis.gif

Granted it's at a high AoA. I'm just concluding what I have read
about wing curvature is consistent with what I see the smoke doing in
the picture.

But it would do the same thing with a flat airfoil.

The explanation of why wings with greater curve bend the air down
more I wouldn't want to say without studying aerodynamics more
thoroughly.

A greater curve does not increase downwash, unless it also changes the
effective angle of attack. AOA is everything.


No, it sin't everything, fjukktard


Bertie

What you don't mention is that there's also downward component to that
airflow, when it impacts the gyrocopter blades and is knocked downward.
The air gets knocked downard, the blades get knocked upward, the
gyrocopter is attached to the blades, it gets held up in the air -- so
the magic is revealed once again as "downwash".


Nope

Have we got a birth of a new, less user friendly to MX, MX sockpuppet in
flightoffancy, Bertie?

The style seems rather familiar.

I'll be hard to convince otherwise.
--
Jim in NC

"Morgans" wrote in news:XgdOi.52$mo6.24
@newsfe03.lga:

What you don't mention is that there's also downward component to that
airflow, when it impacts the gyrocopter blades and is knocked downward.
The air gets knocked downard, the blades get knocked upward, the
gyrocopter is attached to the blades, it gets held up in the air -- so
the magic is revealed once again as "downwash".


Nope

Have we got a birth of a new, less user friendly to MX, MX sockpuppet in
flightoffancy, Bertie?

The style seems rather familiar.

I'll be hard to convince otherwise.

Dunno, I haven't bithered looking up headers. He'd use a proxy anyway..


He'll reveal himslef by and by anyway.


Bertie

Matt Whiting wrote in
:

wrote:
flightoffancy wrote:
In article ,
says...
The air through the rotor disk of a gyrocopter flows upward, yet
gyrocopters fly.


I wrote "helicopter" -- not gyrocopter.

They are not aerodynamically the same.

I know what you wrote and I know they are not the same.

The point is that any theory that says an aircraft flys by forcing
air downward fails to explain how gyrocopters and gyroplanes fly.

How so? Just because the airflow is up through the gyro disk, doesn't
mean that the air isn't deflected downward by the passage of the rotor
disk. Did you ever notice how much AOA a gyro disk has? Think about
why this is?


The alpha is in the blades, not the rotor.



Bertie

flightoffancy wrote in
:

In article ,
says...
flightoffancy writes:

Yes, the angle of attack gives the greater impulse to knock the air
downward. But a curved upper surface gives even more downard force
to the air.

No, the curved surface simply reduces drag and/or increases the stall
angle.


I don't deny those facts; but the greater the curve of the wing the
more the air pushes down behind the wing.



Nope

Bertie

Bertie the Bunyip wrote:
flightoffancy wrote in news:MPG.2172e043702d7a5d989681
@news-server.hot.rr.com:

In article ,
says...

"Nope, wrong" to which claims I made?

I freely admit that my knowledge of aerodynamics is lacking. But I'm
absolutely correct about Lapin's training (or utter lack thereof, in
this case).

It's completely absurd for someone who has not studied aeronautical
engineering to stand up on a soap box and announce that the work of
several generations of aeronautical engineers is WRONG -- and that
he's
leading the charge to finding out what the facts of aerodynamics
really
are.

Lapin does this kind of thing on countless other news groups,
especially
computer science groups. He denounces decades worth of work as
inadequate or completely wrong, claims he has the right answer or
merely
wishes to find the right answer, with the result that nearly everyone
on
the group calls him a crank. Anyone who is really an expert in the
area
he's challenging quickly figures out his meager explorations of the
subject are not worth spending any time participating in.

Lapin believes that he is here to TEACH us.

If you can find hundreds of threads started by LCL on Google groups.
He's an incorrigible usenet troll.




The downwash thing is wrong. Yes, there is some dispacemtn of air that
causes lift, but it' only a minor contribution in the bigger scheme of
things.

Bertie

And what about a hovering helicopter? What is holding it up?

Matt

flightoffancy wrote:
I thought I had read in numerous books during training that the primary
component of lift is the air that gets knocked downward by the wing. I
was calling that "downwash". Maybe my concept of downwash is wrong,
maybe it's a separate consideration from the air that gets knocked
downward by the airfoil. Hell I might not be remembering any of that
correctly.

You appear to have the essential concept right. But aerodynamicists call it
"turning" the flow, which is different from what they call "downwash."
Here's NASA's explanations:

http://www.grc.nasa.gov/WWW/K-12/airplane/lift1.html

And if you click on "turning" you can see this explanation of the term (and
hopefully why "turning" was chosen):

http://www.grc.nasa.gov/WWW/K-12/airplane/right2.html

And this is what aerodynamicists call "downwash" :

http://www.grc.nasa.gov/WWW/K-12/airplane/downwash.html

You should understand that "Bertie" likes to play games with people's
heads. Besides, he has made mistakes with basic physics (e.g. he asserted
with absolute authority and certainty that the only time a person in a
plane would feel 1 gee of force is in straight and level flight.) So if you
are serious you probably shouldn't engage him or take anything he says
seriously. If you want some fun, then by all means have at it.