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Are tube spars an insult to the engineering community?

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jedi

Well-Known Member
Joined
Aug 8, 2009
Messages
4,862
Location
Sahuarita Arizona, Renton Washington, USA
The title of this thread (Are tube spars an insult to the engineering community?) is taken from a post in the "Prandtl lift distribution for conventional configurations" thread?

This inference has been mentioned several times in various areas. I think the subject needs more discussion, in particular in relation to a D spar.

I expect there are several unspecified assumptions among those making the negative statements about tube spars. I have the following questions.

What are those assumptions?

Straight constant wall tube versus tapered or stepped spar or variable wall thickness.

Assuming a cantilever Hershey bar wing what is the % weight penalty for a tube versus I beam?

How is this modified by a strutted wing?

Is the D spar designed as an I beam with a leading edge D for additional torsional stiffness?

If the D spar is constrained to the same material for the entire D is it still superior to the tube spar?

Does the tube versus I beam spar assume or require both a forward and aft I beam spar versus a single tube spar or Ultralight like leading edge and trailing edge tube spars?

How does a non Hershey Bar plan form change the results of the comparison? Taper, elliptical, sweep, etc. ?

How does airfoil pitching moment and / or twist affect the trade study?

All comments welcome.
 
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