On Jun 4, 2:15 pm, Bertie the Bunyip wrote:
Tina wrote :

On Jun 4, 12:30 pm, Bertie the Bunyip wrote:
Tina wrote
innews:db192ddb-52dd-4693-a681-b4f949b66053

@m3g2000hsc.googlegroups.co



m:

On Jun 4, 12:03 pm, Bertie the Bunyip wrote:
Tina wrote
innews:57ee2ec3-c172-4f53-96a3-cec87ee7be22

@k37g2000hsf.googlegroups.c

om:

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.

FAA hs nothing to do with aviation! And as for GPS, it's just a
tidied up and warmed up version of a lot of older distance measured
based stuff like decca and to a lesser extent, tacan, so it's not
really new, just a more advanced and more precise system with the
stations placed in space instead of higgildy-piggildy over the
landscape. It's real hard to find something new under the sun! i
can't think of anything earlier than Decca here, but I'm sure that
even that's based on something that Polynesian sailors or somebody
were doing 4,000 years ago!

Bertie

I have a friend who works for an unnamed branch of the Federal
Government who said he could tell you what really is new in aviation,
but then he said he'd have to kill you,

then shred you,

and put what's left into a burn bag.

So the question before us is, should Bertie be briefed in?

This is how you can tell who your real friends are, Bertie.

Heh heh. I'm insatiably curious so I'm tempted! But unless he's talking
about antigravity, you could probably trace some bit of whatever bit of
airplane he's talking about back to some point way back. In fact, even
if he were talking about antigravity, it's probably got soem of it's
roots in something the Nazis were playing with in Prague or one of
Tesla's half mad notions...

Bertie

In cases like these the argument "I knew that anyhow"when standing on
the threshold of the shredder don't hold a lot of water.

Actually what we are seeing academically is the need for face to face
meetings is beginning to diminish. We worry in the shrink world about
standardized observations in clinical trials, and are getting good
results with teleconferencing instead of having our 'standardized'
observer go to different sites to view subjects. The new thing might
very well be a reduction in business related air travel.

That is also becoming a reality in hi tech business. We are seeing
teleconferencing as effective as meeting face to face, at a great
saving of time and money. Teleconferencing will not, however, replace
the annual two week trip across the country with customers located
about 500 miles apart -- so easy to do by sel, and so difficult most
other ways. We do need to find a potential customer to visit in
Jackson Hole, Las Vegas, and near Lake Tahoe. (You do your business
planning your way, we'll do ours our way).