Ed Sullivan wrote:

On Thu, 16 Jun 2005 02:09:30 GMT, Gord Beaman
wrote:

Ed Sullivan wrote:

On Sat, 11 Jun 2005 00:04:10 -0400, vincent p. norris
wrote:

Friend of mine said at lunch today that the upper wings of biplanes
have no dihedral. Hementioned specificlaly the Stearman PT-17.

I believe he was mistaken. I know the Sopwith Camel upper wing was
flat but I think the PT-17 and most other biplanes have dihedral in
both wings.

Any expert comments?

Thanks. vince norris


Some biplanes have sweptback wings which provide the same effect as
dihedral. My parasol Jungster II has sweepback and no dihedral.

Ed Sullivan

Why is that Ed?...dihedral provides lateral stability by making
the 'downgoing wing' increase it's lift while the 'upgoing'
wing's lift decreases, so how does the 'sweep-back' provide
lateral stability?

The reference escapes me, but I have read that so many degrees of
sweep back is the equivalent of an estabilished amount of dihedral.
All I know for sure is that this little sucker only has a 21' span and
it is as steady as a rock. It will go for miles without touching the
stick.

Ok, thanks...I know that sweepback will increase fore and aft
stability by making the critical fore and aft CG limits 'farther
apart' but I sure can't see how it affects lateral
stability...anyhoo...if you find out could you tip me off?
Thanks Ed.
--


-Gord.

"I'm trying to get as old as I can,
and it must be working 'cause I'm
the oldest now that I've ever been"