On Fri, 17 Jun 2005 20:07:30 GMT, Gord Beaman
wrote:

This is not a complete explanation, but it might help.

http://avstop.com/AC/FlightTraingHan...Stability.html

It does help - but in a disconfirming sense - let me quote:

"The contribution of sweepback to dihedral effect is important
because of the nature of the contribution. In a sideslip the wing into
the wind is operating with an effective decrease in sweepback while
the wing out of the wind is operating with an effective increase in
sweepback. The reader will recall that the swept wing is responsive
only to the wind component that is perpendicular to the wing's leading
edge. Consequently, if the wing is operating at a positive lift
coefficient, the wing into the wind has an increase in lift, and the
wing out of the wind has a decrease in lift. In this manner the swept
back wing would contribute a positive dihedral effect and the swept
forward wing would contribute a negative dihedral effect. "

This suggests that sweepback is directionally destabilizing..... (?)

Brian Whatcott Altus, OK

Yes, I see your point Brian and on a slightly different tack, I
always saw dihedral like this.

A wing has max lift when it's 90 degrees to gravity, (or 'down')
it has zero lift when pointed straight 'up'...now, when a gust
knocks a wing (with dihedral) 'down' (towards level) then it's
lift increases while the other wing's lift will decrease (as it
goes upwards 'toward' the 'zero lift angle'.///
I imagine that the correction then would be somewhat sudden.

-Gord.

I think that I must have read this thread once too many times...in
that when I read what I posted, I see that the "Traing" text implies
just the opposite of what I thought it did. Oh my: he says sweep
back is like dihedral, but the argument seems to point the other way.

Think I will shut up, now!

Brian W