Why Airplanes Fly - Voids Above A Planar Sheet

"Le Chaud Lapin" wrote in message
ps.com...

So yes, I believe this experiment illustrates an important phenomenon
in aerodynamics. It is not the only phenomenon that plays a role, but
it has one, nevertheless. The decriptions of lift that I read in
flight books seem to ignore it.

Subsequently, all the airplanes are falling from the sky.

I recommend building an airplane sometime. The ultimate way to prove your
theory is to be like the Wright Brothers; build it and fly it.

Folks on this forum have logged hundreds of thousands if not millions of
collective hours and all of them have put their asses on the line based on
the aerodynamic principles in books, so you're not going to get much respect
here if you want everybody to do experiments just to discuss to your
otherwise-unproven theories. Some people here have built their own planes,
or engineered airplanes, or maintained them so -their- science is
sufficiently proven. All the discussions and textbooks and usenet theories
in the world aren't worth your first solo flight around the pattern. That
demonstrates that the aerospace engineers proved their wing design and that
the pilots here proved their ability to manipulate that technology. That's
what it takes.

About once a month somebody comes in here and wants to talk about how
aerospace science is all wrong but the thing is, none of 'em ever seems to
have flown an airplane. If you don't do their math for them just the way
they want you to, however, somehow it's all the pilots and plane builders
out here who don't know what they're talking about.

I think your theory would be great put into practice on an experimental
aircraft. I promise you, if you fly it they will come. Best of luck to
you.

-c

On Thu, 4 Oct 2007 14:36:55 -0700, "Gatt"
wrote:


"Le Chaud Lapin" wrote in message
ups.com...

So yes, I believe this experiment illustrates an important phenomenon
in aerodynamics. It is not the only phenomenon that plays a role, but
it has one, nevertheless. The decriptions of lift that I read in
flight books seem to ignore it.

Subsequently, all the airplanes are falling from the sky.

I recommend building an airplane sometime. The ultimate way to prove your
theory is to be like the Wright Brothers; build it and fly it.

Folks on this forum have logged hundreds of thousands if not millions of
collective hours and all of them have put their asses on the line based on
the aerodynamic principles in books, so you're not going to get much respect
here if you want everybody to do experiments just to discuss to your
otherwise-unproven theories. Some people here have built their own planes,
or engineered airplanes, or maintained them so -their- science is
sufficiently proven. All the discussions and textbooks and usenet theories
in the world aren't worth your first solo flight around the pattern. That
demonstrates that the aerospace engineers proved their wing design and that
the pilots here proved their ability to manipulate that technology. That's
what it takes.

About once a month somebody comes in here and wants to talk about how
aerospace science is all wrong but the thing is, none of 'em ever seems to
have flown an airplane. If you don't do their math for them just the way
they want you to, however, somehow it's all the pilots and plane builders
out here who don't know what they're talking about.

I think your theory would be great put into practice on an experimental
aircraft. I promise you, if you fly it they will come. Best of luck to
you.

-c


I will first admit I haven't done the experiments outlined in Lapin's
posts. I will second admit that airplanes do fly. Thirdly I will
admit there are many very good reference books on "why" airplanes fly.
The key word here is "why". The fact that people can design and build
a machine that flies, means they have mastered the elements of design
that allow an aircraft to fly. It doesn't mean they know "why" it
flies. There are accepted theories, disproved theories, questionable
theories and unproven theories, but they are all theories.

Le Chaud Lapin has posted some experiments that in their present form
exhibit some interesting characteristics. Whether or not these
characteristics can be extrapolated to winged aircraft remains to be
seen. Certainly further, much more complex, testing would have to be
done. However, that fact should not provoke the kind of vitriolic
attacks I've seen in this forum. Just because someone posts something
outside the box of conventional thinking is no reason to attack them.
Ron Kelley

On Oct 5, 12:03 am, Ron wrote:
I will first admit I haven't done the experiments outlined in Lapin's
posts. I will second admit that airplanes do fly. Thirdly I will
admit there are many very good reference books on "why" airplanes fly.
The key word here is "why". The fact that people can design and build
a machine that flies, means they have mastered the elements of design
that allow an aircraft to fly. It doesn't mean they know "why" it
flies. There are accepted theories, disproved theories, questionable
theories and unproven theories, but they are all theories.

Le Chaud Lapin has posted some experiments that in their present form
exhibit some interesting characteristics. Whether or not these
characteristics can be extrapolated to winged aircraft remains to be
seen. Certainly further, much more complex, testing would have to be
done. However, that fact should not provoke the kind of vitriolic
attacks I've seen in this forum. Just because someone posts something
outside the box of conventional thinking is no reason to attack them.
Ron Kelley

Thanks Ron.

Given the ratio of ad hominem attacks I have experienced in my first
few days here versus true exploration, I was beginning to wonder if
the 10 people or so who have been responding are representative of
this group, since they do seem to generate the most messages. I saw
your post about 30 seconds after and concluded that perhaps they are
not.

-Le Chaud Lapin-

Le Chaud Lapin wrote:
Given the ratio of ad hominem attacks I have experienced in my first
few days here versus true exploration, I was beginning to wonder if
the 10 people or so who have been responding are representative of
this group, since they do seem to generate the most messages. I saw
your post about 30 seconds after and concluded that perhaps they are
not.

First, I finally found time to read your initial post to this thread. It is
true that all the explanations you've read over the years are not quite
right - that is due to the nature of fluid dynamics. Except for some
trivial examples, the mathematics can't be solved except by numeric
approximation methods. The Bernoulli theorem for example assumes a pre-
existing streamline. It does not actually provide the all-important
streamlines! Otherwise the theorem does take account of all the applicable
conservation laws - but not in a form that can shed much insight into lift
(IMHO).

As to the response you've seen - well, I have some theories but if they are
correct there is nothing I can do, except possibly indirectly. Such as
making this post.

I think for the purposes of piloting that one does not need to know the
Navier-Stokes equations. Because quite honestly the real explanation of
lift is to be found in the differential equations (or integral form)
governing mass continuity, momentum, and energy. All those simple
explanations are just that - simple and obviously incomplete. Rest assured
you're correct in your observations on the inadequate explanations - but
don't make the mistake of assuming a simple _and_ accurate one must exist,
if only you think hard enough on it.

If you are interested in some books on the subject I'd be happy to make
some suggestions.

On Oct 5, 1:11 am, Jim Logajan wrote:
Le Chaud Lapin wrote:
I think for the purposes of piloting that one does not need to know the
Navier-Stokes equations.

That's true.

Because quite honestly the real explanation of
lift is to be found in the differential equations (or integral form)
governing mass continuity, momentum, and energy.

Yes, I agree.

All those simple
explanations are just that - simple and obviously incomplete. Rest assured
you're correct in your observations on the inadequate explanations - but
don't make the mistake of assuming a simple _and_ accurate one must exist,
if only you think hard enough on it.

I never thought that my explanation was complete or accurate. I
offered it because, IMO, it has a sificant influence on airfoil
dynamics. But after reading several books that ignore the partial
vacuum, and one book that was wrongly employing Newton's thereom...
[which is intolerable on any grounds, let alone aerodynamics], I had
to read more.

In his book, "The Proficient Pilot", on page 8, Barry Schiff writes:

"There is, for example, this amusing fable: 'Air flowing above the
wing has a greater distance to travel (because of camber) than air
flowing beneath the wing. Therefore, air above the wing must travel
faster so as to arrive at the wing's trailing edge at the same time as
air flowing underneath. This is pure nonsense."

In his book Learning to Fly With Rod Machado, on page 70, Rod Machado
writes:

"Because air flowing over the wing bends, it is forced to travel a
greater distance than the air flowing underneath. Because it travels a
greater distance, the bent air must move faster on its journey over
the wing. It's this relative increase in wind speed above the wing
that lowers pressure and productes lift."

Since I was new to piloting, I asked a few pilots if they understood
aerodynamics about an airfoil, and they all said yes. The reason they
gave is the one that Rod Machado gave. I asked the older pilots if
they knew who Barry Schiff was, and they said yes. I asked them if
they realized that Barry Schiff did not think that was the reason, and
they said I was mistaken, that Barry Schiff would never be as confused
as I seemed to be about flying. I asked them if they knew who Rod
Machado was. They said yes. I asked them if they thought that Rod
Machado and Barry Schiff would agree. They said yes. I asked them if
they were 100% certain, and they said yes.

Thus began my earnest interest in aerodynamics. I had always been
interested in flying, but this accelerated the interest quite a bit.

I took a sheet of paper and blew over it, the trick that we've all
done, and it went up of course, but I suspected that the reason it
went up was not the reason that was being given by so many people.

I visited a few aero/astro departments online, and while no one is
going to argue with the mathematics of field theory...I did get the
feeling that there were experts in the field saying the opposite
things. So before digging into the math [afterall, there is nothing
wrong with math], I decided to refresh my understanding of Bernoulli's
theorem from my old physics book, and while reading that book, it
occured to me that Barry Schiff's view is more likely right than
not...that is, until I read his explanation of relationship between
Newton and downwash on the next 2 pages of his book. I found a couple
of other books that gave the explanation of downwash that was
similar. Most importantly, I also notice that there was a ***HUGE***
amount of hand-waving going on, far more than one would expect in a
field that has been researched for over a century. I still need to
find a book that I can trust.

I went to the WWW and started reading more aero-astro excerpts, and
concluded that not only is theory still in flux, the experts do not
even agree on the basics. The very basics. Huge amounts of money had
been spent on wind-tunnels. But after all that, I could not get two
experts to agree on the basics. And this was a not simply a matter of
different styles, using integral instead of differential form of
equations, for example, or, deciding where to put a constant, as we
electrical engineers do in our expressions of the Fourier
integrals...there was *fundamental* disgreement about what causes lift
on an airplane.

I asked one of the pilot's again..."How sure are you that the aviation
world understands the basics?" He said he was very sure. He started
rattling off things about NASA.

I begin to imagine airflow over a wing and concluded that pinching at
front of wing must be very important, more important than one would
think, reading the explanations. I also concluded that a glider
should have wings that are very long but with a short cord, which aslo
turned out to be true. I then revisited my physics book...and it
_appeared_ that the application of Bernoulli to flying is wrong in
many contexts, but I decided to not discuss that just yet because it
would be too controversial.

I ask one of the pilots if he thought rarefication had anything to do
with it. He said, "No, it's all Bernoulli." I asked him what would
happen if I did the paper experiment, the one mentioned in my OP, and
he did not know, but said it does not matter because a piece of paper
is not a wing and it does not fly through the air. I asked him if he
understood why the paper would move, and he said, again, it does not
matter. I asked him if he saw any relation between my paper experiment
and the movement of a airfoil, and he said, finally, no, there is
none, because it is all Bernoulli.

I asked a CFI one last time, and he too said it was all Bernoulli,
precisely the argument that Barry Schiff refutes in his book.

So I started imagining, with no mathematics, what goes on with fluids
around surfaces, which lead me to these various experiments.

If you are interested in some books on the subject I'd be happy to make
some suggestions.

Sure.

-Le Chaud Lapin-

Le Chaud Lapin wrote in
oups.com:

On Oct 5, 1:11 am, Jim Logajan wrote:
Le Chaud Lapin wrote:
I think for the purposes of piloting that one does not need to know
the Navier-Stokes equations.

That's true.

Because quite honestly the real explanation of
lift is to be found in the differential equations (or integral form)
governing mass continuity, momentum, and energy.

Yes, I agree.

All those simple
explanations are just that - simple and obviously incomplete. Rest
assured you're correct in your observations on the inadequate
explanations - but don't make the mistake of assuming a simple _and_
accurate one must exist, if only you think hard enough on it.

I never thought that my explanation was complete or accurate. I
offered it because, IMO, it has a sificant influence on airfoil
dynamics.



Ooow! Write Nasa quick! Your research is obviously going to enable the next
critical leap in aeronautical sciences!


Bwawahwhhahwhahwhahwhahwhahwhahwhahawh!


Bertie

Le Chaud Lapin wrote:

I never thought that my explanation was complete or accurate. I
offered it because, IMO, it has a sificant influence on airfoil
dynamics. But after reading several books that ignore the partial
vacuum, and one book that was wrongly employing Newton's thereom...
[which is intolerable on any grounds, let alone aerodynamics], I had
to read more.

Newton had only one theorem? Wow, I always thought he had several...

Matt

"Matt Whiting" wrote in message
...
Le Chaud Lapin wrote:

I never thought that my explanation was complete or accurate. I
offered it because, IMO, it has a sificant influence on airfoil
dynamics. But after reading several books that ignore the partial
vacuum, and one book that was wrongly employing Newton's thereom...
[which is intolerable on any grounds, let alone aerodynamics], I had
to read more.

Newton had only one theorem? Wow, I always thought he had several...

Matt

Not many are familiar with Newton's 4th Law --- "One Fig to a Cookie"

TP

Le Chaud Lapin wrote:
Most importantly, I also notice that there was a ***HUGE***
amount of hand-waving going on, far more than one would expect in a
field that has been researched for over a century. I still need to
find a book that I can trust.

How much math are you willing to deal with?
If you can handle some calculus, then probably the least expensive book I
know of that may fit the bill is:

"Theoretical Aerodynamics" by L. M. Milne-Thomson.
Paperback edition is available from Dover Press.

I went to the WWW and started reading more aero-astro excerpts, and
concluded that not only is theory still in flux, the experts do not
even agree on the basics. The very basics. Huge amounts of money had
been spent on wind-tunnels. But after all that, I could not get two
experts to agree on the basics. And this was a not simply a matter of
different styles, using integral instead of differential form of
equations, for example, or, deciding where to put a constant, as we
electrical engineers do in our expressions of the Fourier
integrals...there was *fundamental* disgreement about what causes lift
on an airplane.

I have no idea what web sites you have visited - all I can say is that
there is _no_ dispute among experts on the very basics. Aerodynamic
models are now run routinely on computers - the field is known as
Computational Fluid Dynamics (CFD) - which would hardly be possible if
the very basics were still in dispute!

I asked one of the pilot's again..."How sure are you that the aviation
world understands the basics?" He said he was very sure. He started
rattling off things about NASA.

NASA is an excellent and authoritative source and you'll be very pleased
to discover they have web pages that address the VERY SAME COMPLAINTS you
have about many of the bogus explanations of lift that are floating
around. Here are two of the most relevant pages you should read:

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

Excerpt from the above:
"Arguments arise because people mis-apply Bernoulli and Newton's
equations and because they over-simplify the description of the problem
of aerodynamic lift. The most popular incorrect theory of lift arises
from a mis-application of Bernoulli's equation."

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

Excerpt from the above:
"There are many theories of how lift is generated. Unfortunately, many of
the theories found in encyclopedias, on web sites, and even in some
textbooks are incorrect, causing unnecessary confusion for students.

The theory described on this slide is one of the most widely circulated,
incorrect explanations. The theory can be labeled the "Longer Path"
theory, or the "Equal Transit Time" theory."


So I started imagining, with no mathematics, what goes on with fluids
around surfaces, which lead me to these various experiments.

It is a great idea to experiment - even with things others already
understand. I do it too.

If you are interested in some books on the subject I'd be happy to
make some suggestions.

Sure.

In addition to the above, there are a couple of other (expensive, alas)
books I would suggest:

"Introduction to Flight" by John D. Anderson, Jr.
Contains a history of the science of flight and also goes into details on
some of the more common mistakes people make in explanations of lift. I
do not own this book, but others also give it great reviews.

"Fundamentals of Aerodynamics" by John D. Anderson, Jr.
A well regarded, though mathematical, text on the subject. I do not own
this book either, but I expect it is good, based on my knowledge of the
next book I mention:

"Computational Fluid Dynamics" By John D. Anderson.
I bought and read through this book a couple years ago and it does a
great job of introducing CFD. I mention it here only because it is how I
know the style and quality of Anderson's writing to confidently recommend
two of his other books (above) that I have not read! He carefully disects
and explains each of the differential equations of the various types used
for computational modeling, among the many things covered.

On Oct 5, 8:31 pm, Jim Logajan wrote:
How much math are you willing to deal with?

I am comfortable with graduate-level mathematics.

If you can handle some calculus, then probably the least expensive book I
know of that may fit the bill is:

"Theoretical Aerodynamics" by L. M. Milne-Thomson.
Paperback edition is available from Dover Press.

Dover. I will assume it is cheap and take a look.

I have no idea what web sites you have visited - all I can say is that
there is _no_ dispute among experts on the very basics.

Well, someone should have told me that Rob Machado and Barry Schiff
are not experts. I did read once that Rod Machado has a Ph.D. in
aviation science, and the foreword to Barry Schiff's book is by Ernest
K. Gann, whom I presumed from his credentials is highly respected in
field. Yet Rob Machado and Barry Schiff said the exact opposite,
Barry clearly stating that what Rob stated was non-sense. Note that
there were not talking about something esoteric how precipitation
beings as condensation on nuclei...they have different opinions on the
most basic phenemenon that _any_ student fascinated with flying would
be inclinded to ask: "Why does the plane stay in the air?" Then we
have Jeppesen, a leaders in edcuation of GA. You would think that,
with such a fine product (no sarcasm meant), that they would have
people whom they trust, experts, at the very high-end of academia, who
could verify what's in the text. But what is in my Jeppensen book and
what Barry Schiff wrote is wrong.

Now I could have gone to some university in the U.S., Germany, France,
and found someone with stratospheric credentials in aero-astro, but
after seeing one expert say that the other is wrong, and then seeing
an incorrect application of Newton's law (yes I still believe it's
incorrect), I had to put on the brakes.

Aerodynamic
models are now run routinely on computers - the field is known as
Computational Fluid Dynamics (CFD) - which would hardly be possible if
the very basics were still in dispute!

Hmm...how shall I say this. It is very similar to what Ron said in my
defense.

In any field of research, there is mind and hand. For artists in the
field, there are those who have a proclivity to use hand more than
mind, and there are those who have a proclivity to use mind more than
hand. In any case, there are typically multiple paths to discovery,
one major path relying heavily on the imagination, the other path
relying on experimentation. Typically there is a combination. Based
on the small amount of the field of aerodynamcis I have seen so far,
and the disputes and inconsistencies, I would not be surprised if
there is an enormous amount of money being spent on experimentation.
Granted, experimentation is very necessary to validate (or invalidate)
what was conceived, but in many fields, there are researchers who
adopt the brute force approach, not completely, but much more than
someone who, lacking $100's of millions in funding would.

I asked one of the pilot's again..."How sure are you that the aviation
world understands the basics?" He said he was very sure. He started
rattling off things about NASA.

NASA is an excellent and authoritative source and you'll be very pleased
to discover they have web pages that address the VERY SAME COMPLAINTS you
have about many of the bogus explanations of lift that are floating
around. Here are two of the most relevant pages you should read:

I will read that...but there seems to be a contradiction of what you
are saying. OTOH, you're saying that there is no disputes amond
experts. On the other hand, you're saying that other people
(institutions) are complaining about the same thing.

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

Excerpt from the above:
"Arguments arise because people mis-apply Bernoulli and Newton's
equations and because they over-simplify the description of the problem
of aerodynamic lift. The most popular incorrect theory of lift arises
from a mis-application of Bernoulli's equation."

Ok, I just read that entire page, and yes, it is comforting to see
that NASA is at least dispelling the myth that is being put forth by
Jeppensen's book and Rod Machado's book. I guess Barry Schiff was
right.

Excerpt from the above:
"There are many theories of how lift is generated. Unfortunately, many of
the theories found in encyclopedias, on web sites, and even in some
textbooks are incorrect, causing unnecessary confusion for students.

Entirely unnecessary.

The theory described on this slide is one of the most widely circulated,
incorrect explanations. The theory can be labeled the "Longer Path"
theory, or the "Equal Transit Time" theory."

So I started imagining, with no mathematics, what goes on with fluids
around surfaces, which lead me to these various experiments.

It is a great idea to experiment - even with things others already
understand. I do it too.

Oh, I plan to.

In addition to the above, there are a couple of other (expensive, alas)
books I would suggest:

"Introduction to Flight" by John D. Anderson, Jr.
Contains a history of the science of flight and also goes into details on
some of the more common mistakes people make in explanations of lift. I
do not own this book, but others also give it great reviews.

"Fundamentals of Aerodynamics" by John D. Anderson, Jr.
A well regarded, though mathematical, text on the subject. I do not own
this book either, but I expect it is good, based on my knowledge of the
next book I mention:

"Computational Fluid Dynamics" By John D. Anderson.
I bought and read through this book a couple years ago and it does a
great job of introducing CFD. I mention it here only because it is how I
know the style and quality of Anderson's writing to confidently recommend
two of his other books (above) that I have not read! He carefully disects
and explains each of the differential equations of the various types used
for computational modeling, among the many things covered.

A lot of J. D. Anderson.

Another note:

On my way to and from a party tonight, I thought in more detail about
Bernoulli's theorem, and I am more certain that not that I understand
the venturi tube, why the fluids, move, the distribution of pressures,
etc. Bernoulli's theorem is, indeed, at work over an airfoil, but is
has nothing to do with the descriptions that are being put forward by
the incorrect texts [really nothing]. All that business about one
side being longer is *not* the reason.

I guess the most important thing I learned from this experiences is
that, if it is true that the field of aerodynamics is fully-cooked,
the experts need to tell everyone else so that they stop printing (as
late as 2006) erroneous information in textbooks about the very
basics.

-Le Chaud Lapin-