Author Topic: Fuselage Top Longeron Gusset Tubes - Necessary or Not?  (Read 658 times)

jonfilipa

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So I'm working on welding on the various odds and ends for my IILS fuselage and am looking for feedback on the whether the tubes labeled A, B, and C in the attached pic are necessary or not.  A couple reasons for asking:
1) I know the "C" tubes have to be left out as it makes getting in and out the plane much easier given my 6 ft 2 in height and 34 in inseam.  (Fred - thanks again for letting me "try on" your airplane at Airventure  8))
2) I'll take whatever weight savings I can get.

That being said, beyond providing some level of gusseting (not necessary in my opinion given load path) do these tubes provide any level of functionality beyond being a hand hold for getting in and out of the airplane?  Just checking to see to make sure I'm not missing something. 

Raceair

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The tubes are there for two reasons.    Reason one,   in a crash,   they tend to send a broken longeron out and away from the occupant, rather than poking into the occupant.   Reason two,    these bays torsionally are inferior without some type of triangulation, and would tend to trapezoid under load without the diagonals.....    The bonus is that they do help as a handhold in getting in....

jonfilipa

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Reason 1 is more than sufficient for me.  Thanks for the feedback Ed!

Pttim

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Looked at mine last night, they are there in the aft compartment but not the front.
Pttim
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Thaddeus

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I'm going to modify this same section on the corvairai.  It's just too dang tight getting in and out and I'm planning on wearing a chute.  The idea of floating down with the bird hanging on my legs just won't do.  Since it will be a 1.5, not a II, I do not care about sacrificing the front seat area.  (Wife has given me a thumbs down vote of confidence).  Instead, there will be more bracing, an aux fuel tank, and the panel will be moved back to the modified cross member.  The cross member will be triangulated, doubled, and gusseted, so it should take any loads.  Here is the plan.
"It seems wisest to assume the worst from the beginning...and let anything better come as a surprise.” 
― Jules Verne, The Mysterious Island

 

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