FILLING THE SPACE BETWEEN WING SPAR AND IN SLEEVE.

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David Teahay

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HI there, the space between the wing spar and an insleeve is about 0.5cm.Hence,there is a visible separation between the wing spar and sleeve,so I decided to put pvc pipe inbetween the wing spar and its sleeves to fill the space between the spar and sleeve.
My question is,is this really a wise idea?...Illustration of what I'm talking about⬇⬇⬇⬇
https://i.stack.imgur.com/xZA0T.jpg
 

Dana

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PVC tube is a bad choice for anything structural. But it's not clear what is this "sleeve" you're talking about.
 

Hot Wings

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Is this a plans built plane or a one of a kind? If it's plans built - AND proven - then just built it per the plans.

If this is a one of a kind then the engineer in charge probably needs to do some rethinking. Filling the gap with PVC is probably better then nothing but hardly a proper solution. Not only is the PVC not as strong or stiff as the aluminum tube its properties will change with temperature enough make it little more then dead weight.

The proper way is to use tubing that is a snug fit and sized for the loads expected. Without knowing the loads all one can do is guess about the structure. Guessing is the way it was done 100 years ago. We can do better today.
 
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Aerowerx

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+1 on Hot Wings.

The best solution is to get the proper size tubing. There are sizes of aluminum tubing that slide into each other with just a couple thousandths of an inch clearance.

As for PVC, when it fails it does not just crumple and bend like a metal tube, it shatters producing knife-like razor sharp shards. Unless it is hot, inch which case it starts to act something like spaghetti.
 

mcrae0104

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David, by "insleeve" do you mean a smaller diameter piece of tubing that is used to splice together two lengths of tubing that are of a larger diameter?
 

Victor Bravo

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Any space between the tubes will allow movement that will weaken and eventually damage the fasteners or the tubes themselves. Putting something soft like PVK in there is better than nothing but it still might not be as good as you need. DEPENDING on what stresses and loads are on the tubes, and in what direction the stresses are, you might be able to use JB weld, PVC, or another aluminum tube to fill that gap.

Since you mentioned that this is a wing spar, we need to know what the purpose of these tubes (all of them) is, and what part of the spars and other components that they attach to.

You have access to a lot of brains and experience on this forum, and all you need to do is provide enough ACCURATE inforrmation so that the people here can at least know how to answer the question.

What type aircraft? Who designed and engineered the aircraft?

Is there SUPPOSED to be a gap between the tubes?

What is the larger tube for? Is it the main wing spar or aa front spar or a rear spar? Diameter and wall thickness of the tube"

Same questions for the smaller sleeve tubes... what do they do, why are they there, what kind of holes or fasteners join the tubes?
 

TFF

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Your life is almost more in the hands of that sleeve than the main tubing. That is a bridge between technically two broken pieces.
 

Dana

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If you're making a sleeved tube splice, the gap should be no more than .005" or so. .058 wall tubing is commonly used with the next size smaller (.125" smaller OD), .120 wall is a slip fit over a tube .250" smaller. With those gaps no filler is needed.
 

Aerowerx

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And it should be pointed out (again...has been several times before here on HBA)....

"Tube" is a structural component, designed to take mechanical loads.

"Pipe" is a conduit, designed to move liquids or gases from one place to another.

Sounds to me like something is wrong somewhere, if you have that big a gap between two structural components.
 

mcrae0104

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"Pipe" is a conduit, designed to move liquids or gases from one place to another.
Except when that conduit is EMT (electrical metallic tubing), which despite its name is neither a pipe nor a tube. :gig:
 

Aerowerx

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Except when that conduit is EMT (electrical metallic tubing), which despite its name is neither a pipe nor a tube. :gig:
It should also be pointed out that 99.99% of structural tubing is extruded. Pipe is sometimes extruded (such as PVC) and sometimes bent from a ribbon and then welded on the seam (Like EMT).
 

Dana

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Actually welded structural tubing isn't unusual at all, particularly square and rectangular tubing. And even round; Dillsburg used to sell welded DOM (drawn over mandrel) 4130 tubing. It wasn't recommended for critical aircraft parts but the race car guys used a lot of it.
 

TFF

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I believe all the steel we use is welded tube. It all started out as ERW welded and then the extra step of DOM smoothes the weld.
 

Aerowerx

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Actually welded structural tubing isn't unusual at all, particularly square and rectangular tubing. And even round; Dillsburg used to sell welded DOM (drawn over mandrel) 4130 tubing. It wasn't recommended for critical aircraft parts but the race car guys used a lot of it.
In a race car, you have only 3 directions to crash. In an airplane you have 4 (left, right, straight, down)
 
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