Mxsmanic , IFR sensations, and some other stuff

BDS wrote:
On May 21, 12:56 pm, Mxsmanic wrote:

Stealth Pilot writes:
aeroplanes fly because of lift generated by pressure differences on
the wing surfaces.
Airplanes fly because the wings divert the air through which they pass
downwards, creating a downwash and exerting a force in doing so that
engenders
an opposite force that is lift.

... these pressure differences are caused by the shape
of the aerofoil of the wing ...
The air is diverted because the wing has a positve angle of attack. It
can be
perfectly flat and it will still generate lift.

There is an interesting article in Flying magazine by Peter Garrison that
talks about lift theory.

I thought that one of the most interesting points he made was that the lift
force generated by an airfoil is greater at the optimum angle of attack than
would be the force imparted to it if you were to move it through the air
perpendicular to the air flow at the same speed.

I agree that a flat wing will produce lift at a positive AOA even without an
airfoil shape - it just won't be as efficient as it would otherwise be if it
were shaped like an airfoil, and talk about pitch divergent...

Oh yeah, the article also pretty much discounts Bernoulli as having anything
to do with why a wing produces lift.

BDS


Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect. I just can't understand why there is so much trouble
in the pilot community understanding that Newton and Bernoulli do NOT
conflict in any way whatsoever, and that each explanation is correct in
itself. Newton AND Bernoulli are BOTH present simultaneously on th wing
at any moment lift is being created. EACH creates the other and EACH is
a complete explanation for how lift is created.

You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.
In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!



--
Dudley Henriques

"Dudley Henriques" wrote

Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect.

I would have thought so too but I tend to put a fair amount of weight on
what Garrison says when it comes to this sort of thing.

You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.
In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!

According to the article where Bernoulli falls apart is in the assumption
that the air flowing over the top of the wing arrives at the trailing edge
at the same time that the air flowing under the wing does, and since it has
further to travel it must be going faster thereby lowering the pressure
above the wing. The article states that in fact, this is exactly what does
not happen - the air flowing over the wing actually arrives at the trailing
edge after the air flowing under the wing.

BDS

BDS wrote:
"Dudley Henriques" wrote
Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect.

I would have thought so too but I tend to put a fair amount of weight on
what Garrison says when it comes to this sort of thing.

You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.
In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!

According to the article where Bernoulli falls apart is in the assumption
that the air flowing over the top of the wing arrives at the trailing edge
at the same time that the air flowing under the wing does, and since it has
further to travel it must be going faster thereby lowering the pressure
above the wing. The article states that in fact, this is exactly what does
not happen - the air flowing over the wing actually arrives at the trailing
edge after the air flowing under the wing.

BDS


I think I see where this article has gone wrong.

What Garrison is talking about is the equal transit theory, which is
indeed incorrect, but it's CRITICAL that a pilot reading this completely
understand that it isn't Bernoulli that is incorrect, but rather the
equal transit theory that is incorrect. The equal transit theory is
simply a totally incorrect INTERPRETATION of Bernoulli that has been
passed around for eons by CFI's, pilots, and indeed textbooks as well.

It's quite common for someone writing an article on lift to try and make
a distinction that Bernoulli is incorrect by referencing the incorrect
interpretations that have been out here in the community for many years.
Just remember; the incorrect interpretations that misrepresent Bernoulli
are in fact misrepresentations of Bernoulli, NOT proof in any way
whatsoever that Bernoulli's CORRECT theory is wrong.





--
Dudley Henriques

On May 23, 3:11*am, Dudley Henriques wrote:
BDS wrote:
"Dudley Henriques" wrote
Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect.

I would have thought so too but I tend to put a fair amount of weight on
what Garrison says when it comes to this sort of thing.

You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.
In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!

According to the article where Bernoulli falls apart is in the assumption
that the air flowing over the top of the wing arrives at the trailing edge
at the same time that the air flowing under the wing does, and since it has
further to travel it must be going faster thereby lowering the pressure
above the wing. *The article states that in fact, this is exactly what does
not happen - the air flowing over the wing actually arrives at the trailing
edge after the air flowing under the wing.

BDS

I think I see where this article has gone wrong.

What Garrison is talking about is the equal transit theory, which is
indeed incorrect, but it's CRITICAL that a pilot reading this completely
understand that it isn't Bernoulli that is incorrect, but rather the
equal transit theory that is incorrect. The equal transit theory is
simply a totally incorrect INTERPRETATION of Bernoulli that has been
passed around for eons by CFI's, pilots, and indeed textbooks as well.

It's quite common for someone writing an article on lift to try and make
a distinction that Bernoulli is incorrect by referencing the incorrect
interpretations that have been out here in the community for many years.
Just remember; the incorrect interpretations that misrepresent Bernoulli
are in fact misrepresentations of Bernoulli, NOT proof in any way
whatsoever that Bernoulli's CORRECT theory is wrong.

Spot on. In any case Bernoulli cannot be "wrong" as it it's only an
energy conservation equation.

Cheers

More_Flaps wrote:
On May 23, 3:11 am, Dudley Henriques wrote:
BDS wrote:
"Dudley Henriques" wrote
Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect.
I would have thought so too but I tend to put a fair amount of weight on
what Garrison says when it comes to this sort of thing.
You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.
In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!
According to the article where Bernoulli falls apart is in the assumption
that the air flowing over the top of the wing arrives at the trailing edge
at the same time that the air flowing under the wing does, and since it has
further to travel it must be going faster thereby lowering the pressure
above the wing. The article states that in fact, this is exactly what does
not happen - the air flowing over the wing actually arrives at the trailing
edge after the air flowing under the wing.
BDS
I think I see where this article has gone wrong.

What Garrison is talking about is the equal transit theory, which is
indeed incorrect, but it's CRITICAL that a pilot reading this completely
understand that it isn't Bernoulli that is incorrect, but rather the
equal transit theory that is incorrect. The equal transit theory is
simply a totally incorrect INTERPRETATION of Bernoulli that has been
passed around for eons by CFI's, pilots, and indeed textbooks as well.

It's quite common for someone writing an article on lift to try and make
a distinction that Bernoulli is incorrect by referencing the incorrect
interpretations that have been out here in the community for many years.
Just remember; the incorrect interpretations that misrepresent Bernoulli
are in fact misrepresentations of Bernoulli, NOT proof in any way
whatsoever that Bernoulli's CORRECT theory is wrong.

Spot on. In any case Bernoulli cannot be "wrong" as it it's only an
energy conservation equation.

Cheers

Actually (and I've always found this extremely humorous :-) neither
Bernoulli OR Newton's work was ever directly involved with the
production of lift.

--
Dudley Henriques

"BDS" wrote in message
...
"Dudley Henriques" wrote

Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect.

I would have thought so too but I tend to put a fair amount of weight on
what Garrison says when it comes to this sort of thing.

You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.

That's because Bernoulli's equation is nothing more than Newtons law
(conservation of momentum) applied to a streamline. It's not that hard to
derive Bernoulli's equation from Newtons...

In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!

According to the article where Bernoulli falls apart is in the assumption
that the air flowing over the top of the wing arrives at the trailing edge
at the same time that the air flowing under the wing does,

Bernoullli never said that. Whoever did was an idiot. Do the math. It's not
that hard.
If this were true, airplanes (as we know them) could not fly - they would
not generate enough lift.

and since it has
further to travel it must be going faster thereby lowering the pressure
above the wing. The article states that in fact, this is exactly what
does
not happen - the air flowing over the wing actually arrives at the
trailing
edge after the air flowing under the wing.


Sorry, but, at most speeds the air "over the top" gets there well before the
air flowing under. Do the math. It's not that hard.
Circulation is a good way to model the effects.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote

Sorry, but, at most speeds the air "over the top" gets there well before
the
air flowing under. Do the math. It's not that hard.
Circulation is a good way to model the effects.

You're right - I had that sdrawkcab...

BDS

On May 23, 9:32*am, "Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way
D0t C0m wrote:


You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.

That's because Bernoulli's equation is nothing more than Newtons law
(conservation of momentum) applied to a streamline. It's not that hard to
derive Bernoulli's equation from Newtons...

Nope. It's an energy equation, not inertial.

Cheers

Dudley Henriques wrote:

Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect. I just can't understand why there is so much trouble
in the pilot community understanding that Newton and Bernoulli do NOT
conflict in any way whatsoever, and that each explanation is correct in
itself. Newton AND Bernoulli are BOTH present simultaneously on th wing
at any moment lift is being created. EACH creates the other and EACH is
a complete explanation for how lift is created.

You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.
In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!

Most people seem to want simple, one size fits all answers to
everything and forget that most real life things, e.g. what causes
lift and what causes cancer, are complex and can't be boiled down
into a 10 second sound bite.


--
Jim Pennino

Remove .spam.sux to reply.

wrote:
Dudley Henriques wrote:

Any article that "discounts Bernoulli" as having anything to do with
lift is incorrect. I just can't understand why there is so much trouble
in the pilot community understanding that Newton and Bernoulli do NOT
conflict in any way whatsoever, and that each explanation is correct in
itself. Newton AND Bernoulli are BOTH present simultaneously on th wing
at any moment lift is being created. EACH creates the other and EACH is
a complete explanation for how lift is created.

You can use either Newton or Bernoulli to explain lift, but the correct
way to explain it is to explain how both are correct.
In other words, anytime you have lift being created you have a Newton
explanation AND a Bernoulli explanation occurring at the SAME TIME!

Most people seem to want simple, one size fits all answers to
everything and forget that most real life things, e.g. what causes
lift and what causes cancer, are complex and can't be boiled down
into a 10 second sound bite.


This is exactly correct.

Lift explanation in it's true form is an extremely complicated issue.
Attempts to explain it in one simple sentence is usually very confusing
to a new student pilot.
The closest thing to a one sentence explanation I have seen is that lift
is created by turning an airflow.
Of course this covers Newton and leaves Bernoulli out there to be
discovered later on as one finally comes to realize that you can't turn
the airflow without having the pressure difference :-)

The best way to handle the lift question is to openly discuss both
Newton and Bernoulli and how they interact to create each other while
creating what we call lift.

--
Dudley Henriques