Backwash Causes Lift?

writes:

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

No, it doesn't. The rotor of the gyrocopter is essentially a large airfoil
(in addition to being a set of small rotating airfoils).

Airplanes, helicopters, gyrocopters, and gyroplanes all fly in
level flight due to the lift produced by the wings and/or rotor blades.

And that lift is produced by accelerating a mass of air downwards. There
isn't any other way to fly (except via direct thrust from an engine pointing
downwards, as in a rocket).

writes:

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

But the net movement of air is downward for the entire aircraft, which is why
it flies. The rotor acts as a large airfoil.

On Oct 7, 10:07 pm, Mxsmanic wrote:
Le Chaud Lapin writes:
If that is the case, what is pushing the air?

You may be able to get past this by considering that the airfoil actually
turns the flow, rather than push or pull it. It turns the flow downwards, and
this acceleration of the air mass engenders an upward force that is lift.

The airfoil turns the flow downward....

What air gets turn downward....the air on top of the wing or the air
on the bottom of wing?

-Le Chaud Lapin-

Mxsmanic wrote:
writes:

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

But the net movement of air is downward for the entire aircraft, which is why
it flies. The rotor acts as a large airfoil.

The disk defined by the rotor blades of a gyrocopter or gyroplane is
tilted slighty back.

The air always enters from the bottom of that disk and exits from the
top.

If it doesn't, the aircraft stops flying.

There is nothing after leaving the rotor disk to change the direction
of air flow.

The airplane, helicopter, gyrocopter, and gyroplane all fly straight
and level for the same reason and it isn't air being deflected
downward.

--
Jim Pennino

Remove .spam.sux to reply.

On Oct 7, 11:02 pm, flightoffancy wrote:
Did you mess with NASA's online simulations of airfoils?

Yes, 15 minutes ago, in fact after taking a break from my very tedious
work.

Those suggest that the air both "on top" and "on the bottom" of an
airfoil get turned as the airfoil's AoA changes. Those have to be put in
quotes since an aircraft (with the proper engine) can be flown upside
down and in other orientations.

I did notice the turning. The article is claiming that the upper
surface of the wing "turns" the upper flow.

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

I must admit that I am having problems with this explanation. It is
extremely vague? What is the turning? How, exactly, does the wing
"turn" the flow. The air is made up of molecules. If it is upper
surface of the wing that is turning does air molecules so that they
have a velocity component that is downward, how is this happening?
Since when, could one body, A, of any kind, that does not involve
gravitational or electrostatic fields, induce another body B, to move
in a direction that has a component vector that is aimed directly at
B?

Also NASA does not just explain why the longer length theory, the
Newtonian theory, and Bernoulli theories are incorrect, they also
elaborate what the correct equations to properly calculate observed lift
are, though I didn't see an example calculation. So they do say what is
correct, as well as what is not.- Hide quoted text -

True.

This "turning" theory of NASA makes me suspicious. If anyone else has
any qualtitative explanation of what they mean by the upper surface of
the wing foil turning the air so that it has a downward component in
its velocity, I would like to see it.

Finally, I do agree that the geometry, AoA, etc...interacts with the
atmospher in such a way that the net result of the flow on the top
surface of the wing is back and downward. What I don't see is the how
the wing itself is "turning" that flow.

-Le Chaud Lapin-

Le Chaud Lapin writes:

The airfoil turns the flow downward....

What air gets turn downward....the air on top of the wing or the air
on the bottom of wing?

Both, but mostly air from above the wing (a great deal of air, in fact).

writes:

There is nothing after leaving the rotor disk to change the direction
of air flow.

The airplane, helicopter, gyrocopter, and gyroplane all fly straight
and level for the same reason and it isn't air being deflected
downward.

No heavier-than-air aircraft flies without deflecting air downward, unless it
is supported directly by the thrust from its engines.

On Oct 7, 11:58 pm, Le Chaud Lapin wrote:
On Oct 7, 11:02 pm, flightoffancy wrote:
I did notice the turning. The article is claiming that the upper
surface of the wing "turns" the upper flow.

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

I must admit that I am having problems with this explanation. It is
extremely vague? What is the turning? How, exactly, does the wing
"turn" the flow. The air is made up of molecules. If it is upper
surface of the wing that is turning does air molecules so that they
have a velocity component that is downward, how is this happening?
Since when, could one body, A, of any kind, that does not involve
gravitational or electrostatic fields, induce another body B, to move
in a direction that has a component vector that is aimed directly at
B?

I just re-read the link above very carefully, and unless I am
mistaken, there is a *huge* amount of hand-waving going on here too.
Sigh.

"Turning" a flow? What would Newton say. It's magic.

Yes, we all know that F=ma, and "a" is the time derivative of
velocity, a = dv/dt, and that v has a magnitude and a direction, and
that if you change either magnitude or direction, you have a
force...that's all fine...

They do not specify how the wing turns the air. They show a picture
of air flowing backward on top of a sligtly-angled wing. Then they
write:

"For a body immersed in a moving fluid, the fluid remains in contact
with the surface of the body. If the body is shaped, moved, or
inclined in such a way as to produce a net deflection or turning of
the flow, the local velocity is changed in magnitude, direction, or
both. Changing the velocity creates a net force on the body. It is
very important to note that the turning of the fluid occurs because
the molecules of the fluid stay in contact with the solid body since
the molecules are free to move."

"the molecules stay in contact with the solid body"...?????????????

Why?

What incentive do the molecules have to stay in contact with the solid
body? Is there a sign on top of the wing that reads:

**** NOTE: ALL MOLECULES, YOU ARE HEREBY ORDERED TO STAY AS CLOSE TO
ME AS POSSIBLE. ****

Are there little molecule-sized pina coladas on top of the wing
waiting for the molecules to drink?

Even if there is a thin layer of air remaining in contact with the
wing for mysterious, magical reasons, what about the layers above it?
What incentive do those layers have "try and stay in contact with the
wing"?

-Le Chaud Lapin-

Mxsmanic wrote in
:

writes:

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

But the net movement of air is downward for the entire aircraft, which
is why it flies.


Nope.


Wrong again, dip****.

Bertie

Mxsmanic wrote in
:

writes:

There is nothing after leaving the rotor disk to change the direction
of air flow.

The airplane, helicopter, gyrocopter, and gyroplane all fly straight
and level for the same reason and it isn't air being deflected
downward.

No heavier-than-air aircraft flies without deflecting air downward,


Yes, they can, and do.

Dynamic lift is usually at play but is by no means required.

Bertie