negative dihedral

"Ken S. Tucker" wrote in news:ce62c207-10e1-
:

On Jun 3, 5:05 pm, wrote:
Tina wrote:
I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor, has a
pronounced negative dihedral -- the wings have a noticeable
downward
slope.

No idea of why or how it stays upright.

From the pictures I've seen of it in the air, most of that negative
dihedral seems to go away while flying.

Yup, here's an example.
http://www.google.com/search?hl=en&q...=Google+Search
Ken

Oh well done there Ken.

Why don't you 'splain it using a paper airplane, some paper clips and a
can of sterno?

Bertie

On Jun 3, 11:35 pm, Bertie the Bunyip wrote:
Tina wrote in news:28472a75-654d-447f-9317-
:





On Jun 3, 10:25 pm, Bertie the Bunyip wrote:
Tina wrote in news:d9fb071f-4d30-45c3-916d-
:

I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor, has a
pronounced negative dihedral -- the wings have a noticeable
downward
slope.

That's called Anhedral..

Q1: Do those airplanes need active fly by wire controls to maintain
stability, or is something else at play that keeps them right side
up?

Nope.

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can appreciate
why
fighters have it -- they exploit lack of aerodynamic stability for
rapid maneuvers -- but transports that spend their whole life
being
straight and level are another issue.

Well, the anhedral negates what can be excessive stability that comes
form the sweep of the wings. Sweep provides a very similar kind of
stability as does dihedral and the addition of anhedral negates some
of
this and keeps the airplane form becoming so stable that it can't
even
be maneuvered!
Most of the airplanes with pronounced anhedral are high wing and
would
have parasol stability as well. The anhedral helps neutralise some of
that. Some low wing Russian jets have anhedral, but it's quite small
Their sweep is quite marked and the anhedral is there to ammeliarate
that. The 727 had a fairly radical sweep and you will notice, that
though it has dihedral it's very little compared to the 737 or
similar.

Note: I have not morphed into an Mx clone!

We'll know for sure if you tell me this answer is completely wrong
because your MSFS 172 doesn't have anhedral.

Bertie

Only after a very hard landing would a 172 develop negative dihedral.
A Mooney, on the other hand, given the placement of the wheels, would
either increase its positive dihedral, or more likely, given how
strongly they are built, put a dent in the runway.

I think there have been a couple of straight wing airplanes wiht
anhedral, but I can't picture one off the top of my head. Surely
everything that can be tried, has been tried at this stage!

Bertie

The everything that can be tried had been tried notion is out of
fashion, I don't think the patent office will be closing anytime soon,
or that Ratan's Scaled Composites will be closing up his shop. You can
bet someone will be trying an airplane with one wing over the other
soon. What would you call such a thing -- a redundant winged airplane?
For sure, in these days of political correctness, it would not be
called bi, would it?

Where are my meds?

On Jun 4, 4:49 am, HARRY POTTER wrote:
Tina wrote:
I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor, has a
pronounced negative dihedral -- the wings have a noticeable downward
slope.

Q1: Do those airplanes need active fly by wire controls to maintain
stability, or is something else at play that keeps them right side up?

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can appreciate why
fighters have it -- they exploit lack of aerodynamic stability for
rapid maneuvers -- but transports that spend their whole life being
straight and level are another issue.

Note: I have not morphed into an Mx clone!

The AN124 does not have negative dihedral. It just looks that way when it's
on the ground because the weight of the engines bends the wings so they
look drooped down. Once it's in the air, the fuselage bends the wings the
other way, so it actually does have dihedral.

--http://onlinelogbook.net

Thanks -- didn't realize it was simply wing droop when they are not
developing lift. That's what happens when you fly in stiff winged
little airplanes, you start overlooking something as obvious as that.

Tina wrote in news:d86791d1-d1cd-4256-8c9e-
:

On Jun 3, 11:35 pm, Bertie the Bunyip wrote:
Tina wrote in news:28472a75-654d-447f-9317-
:





On Jun 3, 10:25 pm, Bertie the Bunyip wrote:
Tina wrote in news:d9fb071f-4d30-45c3-
916d-
:

I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor,
has a
pronounced negative dihedral -- the wings have a noticeable
downward
slope.

That's called Anhedral..

Q1: Do those airplanes need active fly by wire controls to
maintain
stability, or is something else at play that keeps them right
side
up?

Nope.

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can
appreciate
why
fighters have it -- they exploit lack of aerodynamic stability
for
rapid maneuvers -- but transports that spend their whole life
being
straight and level are another issue.

Well, the anhedral negates what can be excessive stability that
comes
form the sweep of the wings. Sweep provides a very similar kind of
stability as does dihedral and the addition of anhedral negates
some
of
this and keeps the airplane form becoming so stable that it can't
even
be maneuvered!
Most of the airplanes with pronounced anhedral are high wing and
would
have parasol stability as well. The anhedral helps neutralise some
of
that. Some low wing Russian jets have anhedral, but it's quite
small
Their sweep is quite marked and the anhedral is there to
ammeliarate
that. The 727 had a fairly radical sweep and you will notice, that
though it has dihedral it's very little compared to the 737 or
similar.

Note: I have not morphed into an Mx clone!

We'll know for sure if you tell me this answer is completely wrong
because your MSFS 172 doesn't have anhedral.

Bertie

Only after a very hard landing would a 172 develop negative
dihedral.
A Mooney, on the other hand, given the placement of the wheels,
would
either increase its positive dihedral, or more likely, given how
strongly they are built, put a dent in the runway.

I think there have been a couple of straight wing airplanes wiht
anhedral, but I can't picture one off the top of my head. Surely
everything that can be tried, has been tried at this stage!

Bertie

The everything that can be tried had been tried notion is out of
fashion, I don't think the patent office will be closing anytime soon,
or that Ratan's Scaled Composites will be closing up his shop. You can
bet someone will be trying an airplane with one wing over the other
soon. What would you call such a thing -- a redundant winged airplane?
For sure, in these days of political correctness, it would not be
called bi, would it?

Well, years ago a hypersonic bipe was looked at, believe it or not, but
even Beurt Rutan will tell you that none of his creations were
completely original. Not to detract from his talent, whihc is monstrous,
but there's nothing on any of his airplanes that hadn't been done
before. Even that mad boomerang has precedants and quite a lot of them
dating back to the first world war (Caproni). Getting it all arranged
right to make it go better than anything before it is his gift. Having
said that, Spaceship one was pretty unique, but you'll probably find
that mad recovery system was done in boost glider in an old issue of
American Aircraft Modeler or similar. I never cease to be astounded at
the massive number of airplanes constructed in th elast century and the
variety. it hardly seems possible sometimes that there were enough
people to make them all!


Bertie



Bertie

Where are my meds?

HARRY POTTER wrote in
:

Tina wrote:

I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor, has a
pronounced negative dihedral -- the wings have a noticeable downward
slope.

Q1: Do those airplanes need active fly by wire controls to maintain
stability, or is something else at play that keeps them right side
up?

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can appreciate why
fighters have it -- they exploit lack of aerodynamic stability for
rapid maneuvers -- but transports that spend their whole life being
straight and level are another issue.

Note: I have not morphed into an Mx clone!

The AN124 does not have negative dihedral.

That's right, it has anhedral.



It just looks that way when
it's on the ground because the weight of the engines bends the wings
so they look drooped down. Once it's in the air, the fuselage bends
the wings the other way, so it actually does have dihedral.#


Nope.

Bertie

Tina wrote in
:

On Jun 4, 4:49 am, HARRY POTTER wrote:
Tina wrote:
I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor, has a
pronounced negative dihedral -- the wings have a noticeable
downward slope.

Q1: Do those airplanes need active fly by wire controls to maintain
stability, or is something else at play that keeps them right side
up?

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can appreciate
why fighters have it -- they exploit lack of aerodynamic stability
for rapid maneuvers -- but transports that spend their whole life
being straight and level are another issue.

Note: I have not morphed into an Mx clone!

The AN124 does not have negative dihedral. It just looks that way
when it's on the ground because the weight of the engines bends the
wings so they look drooped down. Once it's in the air, the fuselage
bends the wings the other way, so it actually does have dihedral.

--http://onlinelogbook.net

Thanks -- didn't realize it was simply wing droop when they are not
developing lift. That's what happens when you fly in stiff winged
little airplanes, you start overlooking something as obvious as that.


http://www.youtube.com/watch?v=WJscAaKfr7A

Bertie

Bertie the Bunyip wrote in news:Xns9AB3A5306F330****upropeeh@
208.90.168.18:

Tina wrote in
:

On Jun 4, 4:49 am, HARRY POTTER wrote:
Tina wrote:
I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor, has
a
pronounced negative dihedral -- the wings have a noticeable
downward slope.

Q1: Do those airplanes need active fly by wire controls to
maintain
stability, or is something else at play that keeps them right side
up?

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can appreciate
why fighters have it -- they exploit lack of aerodynamic stability
for rapid maneuvers -- but transports that spend their whole life
being straight and level are another issue.

Note: I have not morphed into an Mx clone!

The AN124 does not have negative dihedral. It just looks that way
when it's on the ground because the weight of the engines bends the
wings so they look drooped down. Once it's in the air, the fuselage
bends the wings the other way, so it actually does have dihedral.

--http://onlinelogbook.net

Thanks -- didn't realize it was simply wing droop when they are not
developing lift. That's what happens when you fly in stiff winged
little airplanes, you start overlooking something as obvious as that.


http://www.youtube.com/watch?v=WJscAaKfr7A


Ooops, that was a MSFS one.

Here's an actual aiplane taking off...


http://www.youtube.com/watch?v=BcyRy...eature=related

Which clarly shows the sockpuppet is wrong.


Bertie

On Jun 4, 11:23 am, Bertie the Bunyip wrote:
Tina wrote :



On Jun 4, 4:49 am, HARRY POTTER wrote:
Tina wrote:
I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor, has a
pronounced negative dihedral -- the wings have a noticeable
downward slope.

Q1: Do those airplanes need active fly by wire controls to maintain
stability, or is something else at play that keeps them right side
up?

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can appreciate
why fighters have it -- they exploit lack of aerodynamic stability
for rapid maneuvers -- but transports that spend their whole life
being straight and level are another issue.

Note: I have not morphed into an Mx clone!

The AN124 does not have negative dihedral. It just looks that way
when it's on the ground because the weight of the engines bends the
wings so they look drooped down. Once it's in the air, the fuselage
bends the wings the other way, so it actually does have dihedral.

--http://onlinelogbook.net

Thanks -- didn't realize it was simply wing droop when they are not
developing lift. That's what happens when you fly in stiff winged
little airplanes, you start overlooking something as obvious as that.

http://www.youtube.com/watch?v=WJscAaKfr7A

Bertie

OK, I see some of the downslope was washed out in flight, but it was
still obvious there. Thanks

I expect more is washed out when the airplane is at gross weight, but
your point is made, Bertie.

Tina wrote in
:

On Jun 4, 11:23 am, Bertie the Bunyip wrote:
Tina wrote
innews:4cc0ec37-d80c-4006-9190-

m:



On Jun 4, 4:49 am, HARRY POTTER wrote:
Tina wrote:
I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor,
has a pronounced negative dihedral -- the wings have a
noticeable downward slope.

Q1: Do those airplanes need active fly by wire controls to
maintain stability, or is something else at play that keeps them
right side up?

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can
appreciate why fighters have it -- they exploit lack of
aerodynamic stability for rapid maneuvers -- but transports
that spend their whole life being straight and level are another
issue.

Note: I have not morphed into an Mx clone!

The AN124 does not have negative dihedral. It just looks that way
when it's on the ground because the weight of the engines bends
the wings so they look drooped down. Once it's in the air, the
fuselage bends the wings the other way, so it actually does have
dihedral.

--http://onlinelogbook.net

Thanks -- didn't realize it was simply wing droop when they are not
developing lift. That's what happens when you fly in stiff winged
little airplanes, you start overlooking something as obvious as
that.

http://www.youtube.com/watch?v=WJscAaKfr7A

Bertie

OK, I see some of the downslope was washed out in flight, but it was
still obvious there. Thanks

I expect more is washed out when the airplane is at gross weight, but
your point is made, Bertie.


Um, washout is probably not the best term, being share with another
important wing feature, but yeah, it's still there even when the
airplane is very heavy. I've seen the 225 fly and it's the same. There'a
also the little BAe 146 and the C5 and the C141 and the other little bay
antonov etc. I also mentioned I had seen some striaght wing airplanes
with anhedral but couldn't remember where. Most of the turboprop
antonovs have anhedral, but not nearly as much as the jets. He obviously
liked his airplanes to be manueverable!
Even a lot of the low wing jets had anhedral. The IL 62, for
instance.and IIRC some of the Tupovlevs also had it.

On Jun 4, 12:03 pm, Bertie the Bunyip wrote:
Tina wrote :

On Jun 4, 11:23 am, Bertie the Bunyip wrote:
Tina wrote
innews:4cc0ec37-d80c-4006-9190-





m:

On Jun 4, 4:49 am, HARRY POTTER wrote:
Tina wrote:
I understand how positive dihedral helps dynamic stability in
airplanes, but some big ones, like the Russian An 124 Condor,
has a pronounced negative dihedral -- the wings have a
noticeable downward slope.

Q1: Do those airplanes need active fly by wire controls to
maintain stability, or is something else at play that keeps them
right side up?

Q2: Does anyone have a design rationalization for such a
configuration, as opposed to just zero dihedral? I can
appreciate why fighters have it -- they exploit lack of
aerodynamic stability for rapid maneuvers -- but transports
that spend their whole life being straight and level are another
issue.

Note: I have not morphed into an Mx clone!

The AN124 does not have negative dihedral. It just looks that way
when it's on the ground because the weight of the engines bends
the wings so they look drooped down. Once it's in the air, the
fuselage bends the wings the other way, so it actually does have
dihedral.

--http://onlinelogbook.net

Thanks -- didn't realize it was simply wing droop when they are not
developing lift. That's what happens when you fly in stiff winged
little airplanes, you start overlooking something as obvious as
that.

http://www.youtube.com/watch?v=WJscAaKfr7A

Bertie

OK, I see some of the downslope was washed out in flight, but it was
still obvious there. Thanks

I expect more is washed out when the airplane is at gross weight, but
your point is made, Bertie.

Um, washout is probably not the best term, being share with another
important wing feature, but yeah, it's still there even when the
airplane is very heavy. I've seen the 225 fly and it's the same. There'a
also the little BAe 146 and the C5 and the C141 and the other little bay
antonov etc. I also mentioned I had seen some striaght wing airplanes
with anhedral but couldn't remember where. Most of the turboprop
antonovs have anhedral, but not nearly as much as the jets. He obviously
liked his airplanes to be manueverable!
Even a lot of the low wing jets had anhedral. The IL 62, for
instance.and IIRC some of the Tupovlevs also had it.

There was a country music guy who had a Mitsubishi twin with what I
remember looked liked pronounced anhedral, but I did a web search and
couldn't find a photo of it. What I am remembering might have been in
the 1970s.

There's little doubt in my mind that a high wing configuration with
negative dihedral would be more stable than a low winged one -- the cg
being way under the center of lift would see to that -- but still
don't have a 'model' to explain why wing sweep is a factor: when I
have some time I'll think about that, or I suppose I could ask
Anthony.

As for new stuff in aviation? I'd say GPS, released to the general
public during the RR presidency because of the Koran jet shootdown in
Russia, is fairly new. And let us not forget the new and improved FAA.

I'm doing my part to add to the recreation in rec.aviation (and trying
to not have it be wreck.aviation).