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Fuselage Bulkhead/Rib question; Curved flanges

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Chlomo

Well-Known Member
Joined
Oct 8, 2014
Messages
120
Location
Seoul
Hi forum!
Good day to build airplanes! Or to design one.. Or maybe just to think about designing one.
Some food for thought;
How does one create professional looking(and correspondingly strong) curved flanges?
When a flange is straight like the ones in Sonex there is little issue in designing such flanges.
But suppose we have some fairly graceful lines maybe more suitable for composite fuselages(and we're trying to do it with aluminum).

My observations so far;

-984002212284532864.jpg img_0519.jpg

for the more curvier or less load carrying areas you split the flanges into multiple segments. Left image is a bulkhead from a Piper and we can appreciate the clever clever reinforcement. And note the smoothness of corner flange. It's more elegant and looks stronger than segmented flanges found on RVs.
What does a homebuilder should do to duplicate such piece?

Turning our attention to the image on the right it is evident that the flanges are not perpendicular to their bulkheads.
Would there be any strength or stiffness related issues compared to 90 degree flanges? Or must we use stiffners?
The photo below demonstrates an effort to align rib flanges exactly perpendicular to rib as the wing is untapered. This is going to be more difficult for non 90deg bends.

100_1347.JPG


And for gradual curves more like a straight line flanges typically have ripples(?) between rivet holes thus not making full contact with the skin. I assume some rv wing ribs incorporate this for added stiffness.


03es09_026-640x480.jpg

This is from a Spitfire cockpit. It's not super duper high res but all the flanges seem to bend very very smoothly without any ripples or segments. I wonder how they fabricated those parts..

26scfelgvdrwpw.jpg

Large structures don't seem to have such issues as those flanges can be bent almost linearly with channels segmenting them.
 
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