wrote:
jls wrote:
[...]
A fabric-covered airplane will have two struts on each wing so that
washout can be set, but an all-metal wing requires only one strut since
the wing forms a torsionally-rigid box and the two struts are not
necessary to keep the wing aligned. Those wings (152s, 172s, etc) have
the washout built into them while being skinned at the factory and it's
not adjustable. Incidence is adjustable at the root, but it's a small
range of adjustment.
A rectangular wing generally needs no washout because its
natural stall pattern begins at the root, for reasons I'm not clear on.
Tapered and elliptical wings tend to start stalling at midspan, so
washout will normally be found on them.
Any wing should be rigged in accordance with the aircraft's
service manual. Tampering with wings to introduce washout or washin
where the type design doesn't call for it (or remove whatever setting
is specified) can be dangerous and create unpredictable handling. If an
airplane consistently drops one particular wing in a coordinated stall,
and the washin is set properly, it's more likely an incidence issue,
not washout.
Stall strips were used to modify stall behavior that was
unacceptable during test flights of new designs. The Bonanza has them.
They'll raise the stall speed, but that's better than having the wing
stall toward the tips first and having some really nasty wing drops
(and maybe immediate spins) or very abrupt stalls. Getting the roots to
start stalling first will create turbulence over the tail, causing a
warning buffet, and will often start the nose downward soon enough to
prevent a full stall.

Dan

Thanks, Dan, for the excellent advice. I stand, er..... sit corrected.

About 20 years ago the A&P and I were adjusting washout on Taylorcraft
wings because one of them was heavy. We finally got the rigging done
to satisfaction, but in the meantime, I learned to go to a nice
altitude before trying a stall after adding washin.