Backwash Causes Lift?

On Oct 6, 12:14 am, Le Chaud Lapin wrote:
On Oct 5, 6:32 pm, wrote:

People are going to yell and boo me for saying this, but after taking
a nice long ride tonight on my motorcyle tonight, I thought the
venturi/Bernoulli thing through, and I am 95% certain that that is not
the reason the pressure is lower. In fact, I could probably provide an
experiment showing you a situation where air is moving considerably
faster on top than it is on the bottom, with much higher presure on
the top. What is ironic is that Bernoulli would still be right, but
the interpretation of Bernoulli would fall apart.

You keep talking about designing this experiment. Nothing
was ever accomplished with a lot of empty talk. When are you going to
start proving your theories? If you come up with something truly
revolutionary, we will all bow and scrape and tell our friends that we
had mistakenly defied a true master.


Newton said that for every action there's an equal and
opposite reaction. If you look at the diagrams of airflow here,http://www.av8n.com/how/htm/airfoils.html
scrolling down to Figure 3.2, you'll see that there's upwash ahead of
the wing as well as downwash behind it. the upwash is generated by the
approaching low pressure area above the wing. As the wing passes, the
upwash is converted to downwash; if this isn't Newton at work, I don't
know what is. Newton would be just another dead guy.

Newton did say that. And I looked at that diagram very carefully.
[Thanks for link] The upwash is not casued by an approaching low
pressure. The upwash is caused by a gradient in pressure, going from
high pressure at the leading ede, to low pressure, right above and
slightly-back of the wing, due to rarefication of the wing in motion.

And that's not an effect of the approaching low pressure? In
any subsonic flow, the effect of any disturbance of the air travels
outward at the speed of sound. An approaching wing will affect air
molecule movement well ahead of it.

The area above the rarefication is normal atmosphere that has a
propensity to move toward the lower-pressure, rarefied air. The
combination of that normal atmosphere air, combine with the high
velocity of the molecules from the leading edge of the wing, results
in the flow paths (streams) that you see. I haven't looked yet, but I
imagine that there are aerodynamicists, all over the world, who, if
not for appreciation of the hypothesis I am proposing here, have at
least figured this out empircally, and are fretting day and night
trying to find the optimal shape of the leading edge of the wing.
They have two conflicting objectives:

1. Make the shape in such a way so as to minimize drag.
2. Make the shape in such a way so as to increase pressure to impart
high velocity to air molecules moving up/backwards.

I'll be the first to admit that i don't have the capacity to do so at
this moment, but imagine that that one shape of the leading edge is
not appropriate for all speeds of the aircraft.

Finally, two true statements: 1. You don't have the capacity, and 2.
The leading edge you see is not appropriate for all speeds of
aircraft. There are MANY different leading edges out there. I imagine
you haven't seen them.


For a given set of
context variables like density, temperature, pressure, angle-of-
attack, airspeed, what-the-plane-was-doing-20-milliseconds-ago,
turbulences...wind, etc...there is an optimal shape for that leading
edge, depending on what you are trying to do. It would be quite wild
if someone were to design a wing that could morph, dynamically by
control of a computer, into an instaneously-optimal shape.

As if the engineers haven't been working on these wings for
years already. I have an article on my desk in front of me about
morphing helicopter blades to deal with retreating-blade stall. You
didn't really think you had a new idea, did you?
We already have variable-geometry wings. The fighter's swing-
wings, the airliner's triple-slotted flaps and its leading-edge slats
and flaps, on and on. All varying the airfoil for different speed
regimes and maneuvers. The problem with your instantaneous change is
one of maintaining structural integrity and strength and resistant to
flutter while keeping the weight low enough that it will fly. Maybe
you can solve that for us.


I believe it should be possible to explain a venturi tube, Bernoulli's
principle, and a decent part of why a wing has lift, in about 2-3
pages of written text, with pictures, using no formulas, not even
grade-school mathematics.

Commonly done in many texts. You just haven't read them yet.

If a student wants to argue that the physics as presented are
all wrong he should do extensive research and publish a book on the
subject, not argue with pilots who have been trusting their soft pink
bodies to Bernoulli and Newton for decades.

I definitely agree a paper should be written, and there should be an
element of rigor, obviously lacking in my posts.

Obviously.

There is a flow of goofy ideas through your head,
increasing in velocity, so that a vacuum is forming there.

Dan