Aluminum Drag Tube

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patrick.hvac
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Aluminum Drag Tube

Post by patrick.hvac »

Hello!

Hoping someone can help me find a resource that references standards or acceptability of flattening aluminum tube ends in a smooth jawed vice like the Drag Tubes in the wing.
I recall seeing something that dictated acceptability limits and talked about longitudinal striations or cracking during compression but cant find it in the 43.13 or anywhere else.
Any push in the right direction is appreciated.
Thanks!
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danerazz
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Re: Aluminum Drag Tube

Post by danerazz »

43.13 applies to type-certified aircraft, but is considered best-practices for everything.

EAB provides flexibility by allowing the builder (you) a lot of leeway when it comes to determining what is “acceptable” construction (within reason). While I agree, smashing the end of a tube and pop-riveting it to a spar is probably not ideal, if you really don’t like it you are free to make brackets and attach it that way.
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patrick.hvac
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Re: Aluminum Drag Tube

Post by patrick.hvac »

danerazz wrote:43.13 applies to type-certified aircraft, but is considered best-practices for everything.

EAB provides flexibility by allowing the builder (you) a lot of leeway when it comes to determining what is “acceptable” construction (within reason). While I agree, smashing the end of a tube and pop-riveting it to a spar is probably not ideal, if you really don’t like it you are free to make brackets and attach it that way.
Thanks for the reply. I am not questioning the methodology of existing attachment. I was looking for a bit of guidance on what is an acceptable tube that has been made this way as T6 is prone to cracking when cold formed. I thought I saw it but can't find it now. I recall that some longitudinal cracking was acceptable in the crush zone but horizontal cracking or cracking near attach points was not. Maybe my memory is toast and any cracking is unacceptable..
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alan
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Re: Aluminum Drag Tube

Post by alan »

One thing to remember when flattening the ends of these tubes is to squeeze them very slowly. Doing it fast at all will cause some cracking.
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BDA
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Re: Aluminum Drag Tube

Post by BDA »

You can always add heat to ease cracking - just dont go over 300*F or you will loose your T6 hardness and tensile strength
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