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lmorgan100(at)charter.net
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 Posted: Mon Oct 08, 2012 2:19 pm Post subject: wing strut flutter |
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Hey everyone,
I have been doing some test flights with my newly rebuilt Twinstar MK II.
I have noticed that I am getting some flutter on the wing struts, It seems to happen at pretty much all speeds.
Can anyone give me some ideas on this ?
thanks,
Lee..
[quote][b]
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elleryweld(at)aol.com
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| Posted: Mon Oct 08, 2012 3:41 pm Post subject: wing strut flutter |
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have you got the round struts?
Ellery Batchelder Jr.
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Mon Oct 08, 2012 6:19 pm Post subject: wing strut flutter |
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Lee, If you have unstreamlined struts, you are experiencing the phenomenon of vortex shedding. You can see a very good graphical representation of what's happening here:http://en.wikipedia.org/wiki/Von_K%C3%A1rm%C3%A1n_vortex_street
Rick Girard
do not archive
On Mon, Oct 8, 2012 at 5:18 PM, Lee <lmorgan100(at)charter.net (lmorgan100(at)charter.net)> wrote:
| Quote: |
Hey everyone,
I have been doing some test flights with my newly rebuilt Twinstar MK II.
I have noticed that I am getting some flutter on the wing struts, It seems to happen at pretty much all speeds.
Can anyone give me some ideas on this ?
thanks,
Lee..
| Quote: |
get="_blank">http://www.matronics.com/Navigator?Kolb-List
tp://forums.matronics.com
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Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
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The smallest miracle right in front of you is enough to make you happy.... |
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lmorgan100(at)charter.net
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| Posted: Tue Oct 09, 2012 3:00 am Post subject: wing strut flutter |
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Rick and Ellery,
Yes I have the round struts, is there an inexpensive fix for this or do I need to get some streamline strut covers.
Also is it safe to fly like this ?
thanks.
Lee..
[quote][b]
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elleryweld(at)aol.com
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| Posted: Tue Oct 09, 2012 5:06 am Post subject: wing strut flutter |
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You have a couple options Buy the PVC streamline strut covers from Kolb or Make your own out of aluminum either will stop the vibration of your struts
Ellery Batchelder Jr.
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George Alexander
Joined: 10 Jan 2006
Posts: 245
Location: SW Florida
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| Posted: Tue Oct 09, 2012 8:55 am Post subject: Re: wing strut flutter |
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| lmorgan100(at)charter.net wrote: | Hey everyone,
I have been doing some test flights with my newly rebuilt Twinstar MK II.
I have noticed that I am getting some flutter on the wing struts, It seems to happen at pretty much all speeds.
Can anyone give me some ideas on this ?
thanks,
Lee..
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While you are going over it, check to make sure there is no "slop" at the connecting points. Elongated holes, worn or undersize hardware (clevis pins or bolts), tight brackets at the wing end.
Had an original Firestar with almost 200 hrs. Round struts, no flutter.
As Beauford (and others) sez.... worth what you paid for it.
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_________________
George Alexander
FS II R503
E-LSA N709FS
http://www.oh2fly.net |
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David Lucas
Joined: 10 Jan 2006
Posts: 79
Location: Europe. based Amsterdam NL
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williamtsullivan(at)att.n
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| Posted: Thu Oct 11, 2012 3:37 am Post subject: wing strut flutter |
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David- Thanks. One of the photos shows metal stacks just like the ones on a co-generation plant in town, and I wondered about the strakes.
do not archive
Bill Sullivan
Windsor Locks, Ct.
--- On Thu, 10/11/12, David Lucas <d_a_lucas(at)hotmail.com> wrote:
[quote]
From: David Lucas <d_a_lucas(at)hotmail.com>
Subject: Re: wing strut flutter
To: kolb-list(at)matronics.com
Date: Thursday, October 11, 2012, 5:27 AM
--> Kolb-List message posted by: "David Lucas" <[url=/mc/compose?to=d_a_lucas(at)hotmail.com]d_a_lucas(at)hotmail.com[/url]>
| Quote: | is there an inexpensive fix for this
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My curiosity gets the better of me  I am just wondering if a length of chord wrapped in a helical manner around the strut might stop the vibrations. It would definitely be the most inexpensive fix I would think.
Similar effect to the strakes on chimney stacks. See the nylon chord on the pole of the weather station about half way down this page; http://www.tigranetworks.co.uk/blogs/tigranetworks/preventing-vortex-shedding-with-a-helical-strake/
Like I say, just my curiosity.
David.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=385097#3cs.com/Navigator?Kolb-List" --> http======================== [quote][b]
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jbhart(at)onlyinternet.ne
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| Posted: Sun Oct 14, 2012 6:19 am Post subject: wing strut flutter |
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At 02:27 AM 10/11/12 -0700, you wrote:
| Quote: |
> is there an inexpensive fix for this
My curiosity gets the better of me I am just wondering if a length of
chord wrapped in a helical manner around the strut might stop the
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vibrations. It would definitely be the most inexpensive fix I would
think.
| Quote: | Similar effect to the strakes on chimney stacks. See the nylon chord on the
pole of the weather station about half way down this page;
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http://www.tigranetworks.co.uk/blogs/tigranetworks/preventing-vortex-sheddin
g-with-a-helical-strake/
David,
A cord spiral wound around a round strut will reduce the drag and lessen the
tendency to produce von Karmann vortices that cause the strut to strum.
What you are doing is tripping the boundary layer, which moves the flow
separation further back behind the strut and this reduces the drag.
Spiral cord wrapping with a high pitch angle is much like the smoke stack which has to withstand wind loads from all directions. But with
a wing strut one has to worry about only one direction, and so the tripping
can be accomplished by placing or gluing a wire to the top and bottom sides
of the strut. If you would like to see some better explanation of this
check out page 20 on of:
http://www.bakker.org/dartmouth06/engs150/11-bl.pdf
The struts on my FireFly strummed, and I streamlined my struts and the noise
disappeared. How it was done can be seen at:
http://jackbhart.com/firefly/firefly91.html
Jack B. Hart FF004
Winchester, IN
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