jedi
Well-Known Member
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.
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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