Frank Olson wrote in
news:3Wk1k.4381$C12.2615@pd7urf3no:

Bob Noel wrote:
In article
,
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!

Don't know why, but don't those transports with negative dihedral
also have wings above the hull? So those aircraft have the CG below
the wings.



And large transport aircraft are amongst the most aerodynamically
stable aircraft to fly.


Actually, that's not the case in every sense. They're not very speed
stable, for instance and thye have other problems with two diferent
kinds of dutch roll, related to sweep, mostly.

Bertie