Can Washout Cause Flutter??

"cavelamb himself" wrote in message
link.net...
DonMorrisey wrote:
WERE (because it's probably a moot point now) the hinges and
alieron
actuation mechanism TIGHT (or maybe a little sloppy)?


Well, I actually never saw the airplane. My firiend says they
were
tight but who knows, he also didn't realize the bolts in the
brackets
were too far down from the bend in the spar flange, so I can't
really
say.

He was surprised that the aileron and nothing associated with it
had
any damage. That's what led him to his conclusion that the
washout had
something to do with it.

Don...


As another poster pointed out, we don't know anything about the
design
or construction of this plane.

But you _may_ have just answered your own question.

If the aileron brackets were supported by nothing more than the web
of
the rear spar I wouldn't be surprised it it encountered flutter.

It's an Aero-Elastic phenomenon, remember?

If it can flex, it fer sure will...

Glad nobody was hurt.


A wing being built here at the moment has three steel channel aileron
hinge brackets supported by the rear spar. They are attached to the
web by AN 5-5 bolts. They are also attached to the false spar,
though. That must make all the difference in the world.

Here's something interesting, to me anyways. C. G. Taylor did some
interesting things when he broke away from Bill Piper and tooled up
for the Taylorcraft. He made extensive use of magnesium alloy, in the
wheels, yokes, and aileron hinge brackets. It's light and strong, but
woe unto you when it starts to corrode.

On my Taylorcraft I noticed that the false spar was tight against the
hinge brackets. I should have looked more closely. When the aircraft
was built in the '40's, the false spar holes for the magnesium hinge
brackets were hand-cut, and some of them allowed the aluminum false sp
ar to rub up against the hinge brackets. From the constant faying one
of the magnesium brackets developed a crack over decades of use, and
one day it broke. I noticed the aileron response was mushy.

Thankfully a friend preflighted the aircraft before I flew it again.

"DonMorrisey" wrote in message ups.com...
:
: WERE (because it's probably a moot point now) the hinges and alieron
: actuation mechanism TIGHT (or maybe a little sloppy)?
:
: Well, I actually never saw the airplane. My firiend says they were
: tight but who knows, he also didn't realize the bolts in the brackets
: were too far down from the bend in the spar flange, so I can't really
: say.
:
: He was surprised that the aileron and nothing associated with it had
: any damage. That's what led him to his conclusion that the washout had
: something to do with it.
:
: Don...
:

the aileron & linkage could be stout and break the wing without any damage visible.

Yeah washout has nothing to do with it.

Flutter is equivalent to when you boost yourself on a park swing to go
higher. Your body is the aileron, and the swing chains are the wing
structure, and you move the CG of your body in a harmonic relationship
to the swing to excite and then amplify its movements. The aileron is
doing the same thing if its CG is aft of its hinge line.

By balancing the aileron and putting its CG on the hinge line the
aileron is incapable of adding to the energy in the vibrating wing
structure so stiffness is less critical. Its like laying out horizontal
on the park swing so if someone moves the swing your body just goes
along and can't amplify its motion.

John