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nickc(at)mtaonline.net
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 Posted: Tue Sep 09, 2014 9:25 am Post subject: Anti Flutter idea.... |
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Hello Kolbers,
I had a though about aileron flutter…I have these heavy counter weights that I will be installing on the outboard ends of my ailerons soon.
Disclaimer… I am a True “amateur” so please tell me why this idea is a bad one!
If the idea of these weight is to apply resistance to keep the aileron from fluttering, could this function not also be accomplished by install a fiberglass rod running along the bottom of the end wing rib, and continuing out to the end of the aileron. The rod would flex up or done through the movement on the aileron, but would dampen the aileron movements. Ok, what do you think? Has this ever been tried….did the pilot live?
Thanks,
Nick Cassara
Palmer, Alaska
Fulltime Amateur!
607AK
[quote][b]
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Jim Baker
Joined: 30 Mar 2006
Posts: 181
Location: Sayre, PA
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| Posted: Tue Sep 09, 2014 10:54 am Post subject: Anti Flutter idea.... |
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Bad idea. Now you have created a resonant system that flutters at some unknown airspeed without benefit of wind tunnel or vibratory analysis....in any event, your system does not mass counterbalance the aileron to make it vibration/flutter neutral. Jim Baker--
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byoungplumbing(at)gmail.c
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| Posted: Tue Sep 09, 2014 11:12 am Post subject: Anti Flutter idea.... |
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Nick it is not a resistance,,,, it is a MASS counter balance
a rod from the rib to under the aileron, would increase the working load on the stick, pilot, linkages,,, and make a somewhat heavy aileron near impossible to maneuver,,, IMHO in my humble opinion.
boyd
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
If the idea of these weight is to apply resistance to keep the aileron from
fluttering, could this function not also be accomplished by install a
fiberglass rod running along the bottom of the end wing rib, and continuing
out to the end of the aileron. The rod would flex up or done through the
movement on the aileron, but would dampen the aileron movements. Ok, what do
you think? Has this ever been tried..did the pilot live?
Thanks,
Nick Cassara
This email is free from viruses and malware because avast! Antivirus protection is active. [quote][b]
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kuffel(at)cyberport.net
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| Posted: Tue Sep 09, 2014 11:27 am Post subject: Anti Flutter idea.... |
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Nick,
<< fluttering, could this function not also be accomplished by install a fiberglass rod running along the bottom of the end wing rib, and continuing out to the end of the aileron. The rod would flex up or done through the movement on the aileron, but would dampen the aileron movements >>
I agree with Jim Baker, this is a bad idea. While I'm no expert in aerodynamics either, I use to do flutter and spin testing so have some experience with the issues. A simple thought experiment may help explain why this is a bad idea.
Consider one wing as it goes through a thermal. As the wing enters the thermal, the trailing edge of the aileron will want to go down, on leaving the trailing edge will want to go up. With the counterweight, inertia will resist the entering downward movement and inertia and momentum will resist the exiting upward movement.
With the rod, on entering the rod is flexed upward, on leaving this flex will increase the upward movement of the aileron trailing edge. Doesn't take too much imagination to suspect things could get very bad, very fast. This ignores the mechanical complexity of some sort of flexible mounting to accommodate the different effective length of the rod as the aileron moves.
We have almost 100 years of experience with mass balancing of control surfaces to eliminate flutter. Believe it is best in this case to stick with what is known to work.
Tom Kuffel, CFI etc.
[quote][b]
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Richard Pike
Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee
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| Posted: Tue Sep 09, 2014 7:52 pm Post subject: Re: Anti Flutter idea.... |
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Use the tried and true counterweight method. Your proposal is (quite frankly) a good way to disassemble your Kolb in a remarkably instantaneous fashion..
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_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing. |
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stuart(at)harnerfarm.net
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| Posted: Wed Sep 10, 2014 6:02 am Post subject: Anti Flutter idea.... |
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Nick,
I think your thought process has some merit however, it did not quite go far enough.
Putting a damper on a control surface should indeed help prevent flutter (oscillations).
A thin light weight fiberglass or carbon fiber rod would probably provide the force needed to do the job, insofar as it would absorb some of the energy used to move the control surface from neutral to non-neutral.
Unfortunately, this is where the usefulness of the rod (spring) comes to an end. Now that the spring has all of this stored energy, the only way it can release it is back into the control surface. In flutter, the surface is going to oscillate and the release of the stored energy will only contribute to the problem, adding force to the opposite motion, thus making it worse instead of better.
In short, the rod helps during the first half of the flutter motion, but hurts during the second half. At least until the surface gets back to neutral, then the process starts all over.
What you attempted to do was add a dampener, but what actually happened was you added a spring.
There probably have been entire books written on this subject, all of which I am sure are way beyond me.
A shock absorber of the right size would probably work. Keep thinking, you may come up with a solution that is totally new.
Just my $.02 and a few electrons.
Stuart
From: owner-kolb-list-server(at)matronics.com [mailto:owner-kolb-list-server(at)matronics.com] On Behalf Of Nick Cassara
Sent: Tuesday, September 09, 2014 12:25 PM
To: kolb-list(at)matronics.com
Subject: Anti Flutter idea....
Hello Kolbers,
I had a though about aileron flutter…I have these heavy counter weights that I will be installing on the outboard ends of my ailerons soon.
Disclaimer… I am a True “amateur” so please tell me why this idea is a bad one!
If the idea of these weight is to apply resistance to keep the aileron from fluttering, could this function not also be accomplished by install a fiberglass rod running along the bottom of the end wing rib, and continuing out to the end of the aileron. The rod would flex up or done through the movement on the aileron, but would dampen the aileron movements. Ok, what do you think? Has this ever been tried….did the pilot live?
Thanks,
Nick Cassara
Palmer, Alaska
Fulltime Amateur!
607AK | Quote: | | http://www.matronics.com/Navigator?Kolb-List |
01234567
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