Re: : Rudder balancing

David J. Gall


Sam's account is a classic description of flutter, not just buzz.

In answer to your question, "...anyone still think that balancing it is a
good idea?" Yes, the FAA does in FAR 23.629. I already posted that; try to
keep up.

David J. Gall

-----Original Message-----
From: alfranken2001 [mailto:alfranken@...]
Sent: Saturday, November 01, 2003 4:49 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: : Rudder balancing


Welcome back and congrats.

Now that we have the owner's verson of the story, it like Larry's
version certainly indicates that there is nothing in the design of
the rudder of the Q2-Q2XX airplanes, that has shown iself worthy of
change...certainly no cause for figuring out how to balance one.---

David G's info was certainly interesting, maybe in practical terms
he could suggest, if someone really wanted to waste their time, how
one could come up with a plan to redesign the rudder to make it easy
to balance...I do like James P's idea, but many think that a change
to the rudder is unnecessary, just like the same uniformed idea that
a reflexor is a bad thing...

Well, two for two in world of cable slop and bad springs causing
some rudder chatter, buzz or vibration, or some distant cousin of
flutter...anyone still think that balancing it is a good idea?

I you're not flying yet and still think's probably better
time spent building, rather than fixing something that ain't broke.

I does bring up the point that as our planes age, as things wear,
checking the slop in the hinges and cables is a big deal. I
remember, years ago, being with Bob M. when he was working on his
aileron hinges, replacing the outboard bushing. He had noticed his
ailerons vibrating a lot on the ground and found a lot of slop in
them. He found at some RPM taxiing, that some frequency in the
airframe hit resonance with the ailerons and they shook,a lot.

I suspect the rudder hinge is subject to the same wear, being made
the same way...



In Q-LIST@..., "Sam Hoskins" <shoskins@g...> wrote:
Buzz, flutter, call it what you will, but it shook the crap of the
and it scared the crap out of me. At least till it stopped.

I had this happen on about three occasions on my Q-200, all around
the 190+
mph range. It shook so much I thought I lost a part of the prop
tip or a
cylinder. Throttling back was no direct help, but slowing down to
about 175
stopped it.

Root cause was the cable tension between the rudder bellcrank and
tailwheel was too loose. I tightened the cable turnbuckles a turn
or two
and it never occurred again.

Newlywed Sam

-----Original Message-----
From: David J. Gall [mailto:David@G...]
Sent: Wednesday, October 29, 2003 10:44 PM
To: Q-LIST@...
Subject: RE: [Q-LIST] Re: Rudder balancing


While I was busy researching and typing, I guess everyone else was
answering off-the-cuff. Had I seen these replies, I would have
remarked more
heavily on the parts of the text covering irreversibility of the
and the application of artificial damping. I also would have
mentioned that
the speed range referenced in the text is for anything above 150
mph, and
that the simplified methods outlined in AC 63.629 are only for use
mph, implying that flutter is certainly a possibility below that

I would suspect (no evidence -- wasn't there) that the flutter
Larry refers
to was merely control surface "buzz," a related but far less
harmful cousin
to flutter. However, it certainly could have been flutter,
possibly due to
slop in the hinges and controls, well-lubricated hinges, and/or
the typical
Quickie-style slack rudder cables. I think it is equally plausible
that it
promptly stopped just by putting feet on the rudder pedals or by
slight pressure with feet that were already there. Any change in
the dynamic
will shift the natural flutter frequency, and any stiffening of
the controls
will shift the natural flutter frequency higher requiring more
energy --
higher airspeed -- to keep it fluttering. No need to slow down to
make the
flutter stop in that case.

I'm more inclined to believe ONE pilot who says, "hey, I got
flutter in
mine" than I am to believe a hundred guys who say it can't happen.
(okay, "aeroelasticity") was the subject of the great WWI George
flick "The Blue Max." Lest we forget, NOTHING flew 150 mph in WWI.
The great
Tony Bingelis almost lost his life to flutter in his Piel Emeraude
at about
80 kts. When Larry Koutz and Dave Ekstrom both say it happened to
them in
Q's, I believe them. The next logical item on the agenda is not to
about how "it can't be," but to find out why it almost bit them
and whether
it could happen to the rest of us.

Please carry on,

David J. Gall

-----Original Message-----
From: Tri-Q1 [mailto:rryan@s...]
Sent: Wednesday, October 29, 2003 10:48 PM
To: Q-LIST@...
Subject: [Q-LIST] Re: Rudder balancing

Al, What about this one?


From: "L Koutz" <koutzl@b...>
Subject: Re: [Q-LIST] Tail Wheel and Bellcrank Mods

I got rudder flutter approaching 200 MPH in a dive.


--- In Q-LIST@..., "alfranken2001" <alfranken@m...>
When balancing "a rudder"?.....forward of the hinge point...

When balancing a "Quickie rudder"....forgedaboutit!

Unless you plan to fly a lot faster than any other Q on the
that is.


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