Adjusting Spar and Rib Flanges

[hk1232]

Working on my RV-9 empennage and notice the flanges on the ribs and spars aren't at a 90. I expected this.

Was looking to build out the tool discussed in this thread:
https://vansairforce.net/community/s...e+bending+tool

But I notice that the tool seems to be angled to adjust over-bent flanges. Spot checking both ribs and spars I see they are all under-bent.

1. Are mine already "square enough" and you recommend taking no action?
2. Am I looking at the tool mentioned in the referenced thread wrong and it will in fact work with what I have?
3. Have you built a reversible tool that corrects for both over- and under-bent flanges?

[hk1232]

Ok I'm looking at the tool more closely now -- this will do what I'm looking for.

Assume the hive mind opinion is that these two examples are in fact under-bent and should be adjusted to a straight 90?

[RBR]

Are we looking at the VS?

The 'angle' you are considering adjusting is designed to pickup the taper in the skin as it angles back from a skinny leading edge to a chunkier trailing edge.

If you cleco the structure together you will get a better overview. When it is all together you will get to see the geometry.

As for the ribs, the adjust & flute process will likely have moved the angle again! So re-check the angle after fluting.

Hope this helps!

Is there an EAA Chapter nearby?

[David Paule]

That's my tool in post #3 in that thread. It worked well whenever I had a flange like yours, regardless of which direction it needed to go. But as the previous poster wrote, some flanges aren't supposed to be at 90 deg. to the web, so check first.

Dave

[wirejock]

Like Dave mentioned. Make sure the flange should be adjusted. Spars usually don't need it. Ribs usually but not alwsts. Dave's tool flexes past square then the flange reflexes to 90. It works like a charm.

[Marc Bourget]

Consider forming the rib flange to 85-87 deg and rolling the edge of the rib flange a bit more.

I've seen where the flange will "relax" or open up when riveting and with flight load cycles, leaves a crease in the skin.

FWIW