Pietenpol vertical wing strut support.

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Ed Manigold
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Joined: Tue Jan 09, 2018 3:35 pm

Pietenpol vertical wing strut support.

Post by Ed Manigold » Sun Jan 14, 2018 4:51 pm

I recently bought a Pietenpol built over the last few years. It has an airworthiness certificate issued in 2017. It has been flown by the builder/owner for about 10 hrs. I was wondering if there is any advantage to having the additional vertical wing supports that go from the struts to about the 4th rib of the wing. Why do some have it and some don't? Is it practical to add them? Ed Manigold in Central Texas.

tom kreiner
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Re: Pietenpol vertical wing strut support.

Post by tom kreiner » Mon Jan 15, 2018 11:48 am

Without seeing a picture, you've described what sounds like Jury Struts. These are rather small diameter tubes - or maybe oval tubes - which prevent both buckling and vibration of the main lift struts.

While Jury Struts aren't mandatory, they're highly recommended, and should probably be added to your airframe.

Hopefully, someone who's added them will chime in as to how to add to a covered airframe...

EAB4
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Re: Pietenpol vertical wing strut support.

Post by EAB4 » Tue Jan 16, 2018 10:28 am

Hi Ed

The jury struts serve a definite purpose and need to be on the plane.

Excessive compression loads or harmonic oscillation can cause the lift struts to buckle.
The lift strut material called for in the plans had internal stiffeners, so the early planes did not need the jury struts- today's tubing, round or streamlined
does not have the internal stiffeners so you need to use jury struts to prevent the possibility of the lift struts failing.

English Johnny
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Re: Pietenpol vertical wing strut support.

Post by English Johnny » Wed Jan 17, 2018 7:10 am

In the UK we must have front jury struts only of the oval tube variety.
English Johnny

Edward Manigold
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Re: Pietenpol vertical wing strut support.

Post by Edward Manigold » Wed Jan 17, 2018 12:02 pm

I appreciate your comments about the jury struts for Pietenpol Wings. Since I didn't build the plane I don't have plans that give instructions as to exactly where and how to attach jury strut brackets to the wing spars. Any drawings available? How is it done in England? I would assume it is like the brackets for the main wing struts.

Steve D
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Location: Grand Republic of Texas

Re: Pietenpol vertical wing strut support.

Post by Steve D » Wed Jan 17, 2018 7:47 pm

Boy, those Pietenpol guys know some big words for old country boys! It was broken down for me this way.

The struts take positive Gs. very well since they are very strong in tension (Being pulled apart.) Like when you take off! Or when an updraft hits you.

However, they are considerably weaker in compression (being pushed together). Like when a strong downdraft hits you or when you hit hard on a landing. The tube of the strut can bend if compressed.

Try this take a drinking straw and pull the ends away from each other. Then push the ends toward each other, at some point it bends, usually drastically.

Putting a Jury strut on the main strut simply firms up the middle of the strut and prevents bending in compression.

Blue Skies,
Steve D

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taildrags
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Re: Pietenpol vertical wing strut support.

Post by taildrags » Thu Jan 18, 2018 11:22 pm

Not to put too fine a point on what Steve wrote, "bending in compression" in this case may more clearly be termed "buckling", which may make it clearer since we're all familiar with things that buckle under a load (like my knees). Most wing lift struts are quite slender (a structural term), and without going into a whole discussion on calculating the slenderness ratio of a member under compression loading, it is needless to say that the more slender a member is, the more prone it is to buckling. The jury strut holds the member in position to accept a compression load without beginning to deflect, because once it begins to deflect, that's all she wrote.

I have no idea how the term "that's all she wrote" is translated so that Brits and Aussies can understand it though. Suffice it to say that when the fat lady sings, it's over and that's all she wrote.

English Johnny
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Re: Pietenpol vertical wing strut support.

Post by English Johnny » Sun Feb 04, 2018 6:23 am

Hi Ed, here in the UK the LAA specify jury stuts on the front lift strut only. Unfortunately I cannot access my drawings currently as we are in the process of moving. Once I get done I will scan and post for you.
English Johnny

pauldonahuepilot
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Re: Pietenpol vertical wing strut support.

Post by pauldonahuepilot » Fri Feb 16, 2018 10:06 am

Not at that point yet but have heard its best to mount jerry strut slightly off center to prevent some type of harmonic vibration. ? Paul

VincentDunn
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Location: Salem, OR

Re: Pietenpol vertical wing strut support.

Post by VincentDunn » Mon Aug 20, 2018 11:58 pm

How about for wooden struts? Are jury struts recommended on wooden flying struts too?

EAB4
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Re: Pietenpol vertical wing strut support.

Post by EAB4 » Tue Aug 21, 2018 9:54 am

yes, they should be used with wooden struts as well

MaqFen
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Pietenpol vertical wing strut support

Post by MaqFen » Sun Nov 25, 2018 10:23 pm

Here is another quick question/answer. Please post any suggested improvements

We havent done the "Should my child to on a vertical caving trip?" answer yet. Thats a tricky one that will have to get done soon...

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ubWhat is a€?verticala€

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taildrags
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Re: Pietenpol vertical wing strut support.

Post by taildrags » Mon Nov 26, 2018 10:56 am

Hmmm... not sure what vertical caving trips have to do with vertical wing strut supports, but I see that MaqFen's post originated in Zambia so perhaps that has something to do with it...

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