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Aircraft Design Using .028" Tube?

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Victor Bravo

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Jul 30, 2014
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KWHP, Los Angeles CA, USA
The properly trained engineers here can feel free to correct me, but I believe that on a steel tube truss fuselage you can compensate for some buckling or crippling modes by reducing the distance between the uprights, essentially making more small triangles in the same space as there had been larger triangles.

So if that concept holds true, then making a "tighter" truss out of .028 wall tube could give you the same achieved "strength" as a more open truss (fewer intercostals or uprights) made out of .035 wall tube... which might result in every bit as airworthy of a fuselage, using the low-cost tubing you already have.

Importantly, you could design the fuselage with tighter spacing where it needs to be, then increasing the spacing in the areas where loads are lower. This is another way to skin the same cat as varying the tube diameters at different stations in the fuselage truss (like the Bucker biplanes).
 

Marc W

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Mar 31, 2017
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Colorado
Indeed! I have started some calculations to see where I might go with this. It will take some time.
 

Pops

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Jan 1, 2013
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On the JMR Special, I put the uprights and diagonals spacing in the rear fuselage closer together for the extra weight for the W&B because of the weight of the Cont engine in a small airframe instead of having to add lead weight in the tail that does not add any strength. W&B came out were I wanted. If you need to add weight might as well make it work for you.
 

wanttobuild

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Jun 13, 2015
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kuttawa, ky
I know that I am on alot of ignore lists, but I have a contribution that you may consider.
If I had a tube with a wall thickness of .028, and I thought that it might buckle, and having given this situation alot of thought, I would wrap half the span with packing tape leaving the ends untouched. Then I would wrap the tube with THIN Carbon Tow @ zero degrees. I have tested this and it stiffens the tube alot. So much so, the ends start to deform.
Good luck
 
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