winglets

Eric,

I just wanted to point out that Newton and Bernoulli based explanations
for lift exist. I did reread the articles and as you note neither
discusses top/bottom air pressure in any relative/absolute magnitudes.

KK

http://www.hsa.lr.tudelft.nl/~frits/fig8.jpg

Highly dependant of angle of attack (incidence?), but during cruise (5
degrees) typically only a fraction of the force is generated by the
lower side of the airfoil.

Eric Greenwell wrote:
Ken Kochanski (KK) wrote:
"The rest is generated by lower pressure on the upper side."

hmmmm ...

http://www.eskimo.com/%7Ebillb/wing/airfoil.html

http://www.aa.washington.edu/faculty/eberhardt/lift.htm

Can you point out where these articles compare the pressures on the top
and bottom surface, or some reference that gives the relative
magnitudes? I was unable to find it.

--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

True.
But I`m teaching aerodynamics in my club and it is extremely hard to
explain this to people. I don`t want to confuse people with vorticity
fields so the explanation "pushing air down will result in an
underpressure on top and an overpressure on the lower side of the wing;
that`s lift" seems to be sufficient for the understanding of lift as
far as gliding is concerned.

http://www.navier-stokes.net/

Not too smart to post when you`re just woken up. For those who wanna
know why, just take a look at my last post ;-)

Jarno Nieuwenhuize.
The Netherlands

Ken Kochanski (KK) schreef:

"The rest is generated by lower pressure on the upper side."

hmmmm ...

http://www.eskimo.com/%7Ebillb/wing/airfoil.html

http://www.aa.washington.edu/faculty/eberhardt/lift.htm


Erik Braun wrote:
Hi Wayne,

yet the majority (?) of our lift is generated from the
HIGH pressure BELOW the wing.

No, it only generates 1/3 of the lift. The rest is generated by lower
pressure on the upper side.

I recommend you read
http://www.soaridaho.com/Schreder/Te...lets/Masak.htm
which explains the design and function of winglets.

Greetings, Erik.

True.
But I`m teaching aerodynamics in my club and it is extremely hard to
explain this to people. I don`t want to confuse people with vorticity
fields so the explanation "pushing air down will result in an
underpressure on top and an overpressure on the lower side of the wing;
that`s lift" seems to be sufficient for the understanding of lift as
far as gliding is concerned.

http://www.navier-stokes.net/

Not too smart to post when you`re just woken up. For those who wanna
know why, just take a look at my last post ;-)

Jarno Nieuwenhuize.
The Netherlands

True.
But I`m teaching aerodynamics in my club and it is extremely hard to
explain this to people. I don`t want to confuse people with vorticity
fields so the explanation "pushing air down will result in an
underpressure on top and an overpressure on the lower side of the wing;
that`s lift" seems to be sufficient for the understanding of lift as
far as gliding is concerned.

http://www.navier-stokes.net/

Not too smart to post when you`re just woken up. For those who wanna
know why, just take a look at my last post ;-)

Jarno Nieuwenhuize.
The Netherlands

True.
But I`m teaching aerodynamics in my club and it is extremely hard to
explain this to people. I don`t want to confuse people with vorticity
fields so the explanation "pushing air down will result in an
underpressure on top and an overpressure on the lower side of the wing;
that`s lift" seems to be sufficient for the understanding of lift as
far as gliding is concerned.

http://www.navier-stokes.net/

Not too smart to post when you`re just woken up. For those who wanna
know why, just take a look at my last post ;-)

Jarno Nieuwenhuize.
The Netherlands

True.
But I`m teaching aerodynamics in my club and it is extremely hard to
explain this to people. I don`t want to confuse people with vorticity
fields so the explanation "pushing air down will result in an
underpressure on top and an overpressure on the lower side of the wing;
that`s lift" seems to be sufficient for the understanding of lift as
far as gliding is concerned.

http://www.navier-stokes.net/

Not too smart to post when you`re just woken up. For those who wanna
know why, just take a look at my last post ;-)

Jarno Nieuwenhuize.
The Netherlands

Ken Kochanski (KK) schreef:

"The rest is generated by lower pressure on the upper side."

hmmmm ...

http://www.eskimo.com/%7Ebillb/wing/airfoil.html

http://www.aa.washington.edu/faculty/eberhardt/lift.htm


Erik Braun wrote:
Hi Wayne,

yet the majority (?) of our lift is generated from the
HIGH pressure BELOW the wing.

No, it only generates 1/3 of the lift. The rest is generated by lower
pressure on the upper side.

I recommend you read
http://www.soaridaho.com/Schreder/Te...lets/Masak.htm
which explains the design and function of winglets.

Greetings, Erik.

True.
But I`m teaching aerodynamics in my club and it is extremely hard to
explain this to people. I don`t want to confuse people with vorticity
fields so the explanation "pushing air down will result in an
underpressure on top and an overpressure on the lower side of the wing;
that`s lift" seems to be sufficient for the understanding of lift as
far as gliding is concerned.

http://www.navier-stokes.net/

Not too smart to post when you`re just woken up. For those who wanna
know why, just take a look at my last post ;-)

Jarno Nieuwenhuize.
The Netherlands

bagmaker wrote:


I also note the return of the "plate" style winglet on latest
jetliners, half above, half below the wingtip, instead of a large
winglet.

The latest jetliners (not including Airbus) have gone to the eagle tip
configuration (swept up and back slightly like Nimbus 4's), dumping the
classic style winglet. The 787 and new 747 stretch have this config, I
think a couple of others.

Jim