QQ: Fluting and 90 degree bending

[RudiGreyling]

Just a QQ (quick query) on the main wing ribs.

what do you do first and why?
1) Flute the ribs straight OR
2) Bend the flanges 90 degrees first?

I've read guys do it both ways, but I think to flute it straight first then to bend the flanges 90degrees makes more sense?

Thanx

[painless]

I bent my flanges 90 degrees and then fluted. Otherwise, the flutes may get in the way of bending the flange and/or you could flatten the flutes, thus cancelling out their affect.


Regards,

[RudiGreyling]

Thanks for answering

[RudiGreyling]

OK, I started with bending the main wing rib flanges 90degree first, before fluting the ribs flat, but have another QQ (quick query).

Since the ribs are not yet flat, not fluted, do you press them flat on a table surface before bending the flanges 90 degrees?

The reason i ask is that it seems that if you push them flat and bend the flanges 90degrees, once you release them and they pop back crooked the flange is not 90 degrees any more to the web.

Will the flanges go back to 90 degrees wrt to the web after fluting the rib flat?

I would hate wasting time and bending all the flanges to what I think will be 90 degrees when the rib is pushed flat on the table, only to realise that after fluting them flat the flange does not go back to my 90 degree bend. (i.e. pushing the rib flat and fluting does not strain the rib in the same fashion)

Any experience here would help, before I commit several hours into bending the flanges 90 degrees and potensially redo it.

Thanx in advance.
Rudi

[alpinelakespilot2000]

Rudi--

I would make sure the flanges are close to 90 degrees as possible first (most of mine were pretty close right out of the crate and so I didn't have to do much with the flanges) and then second flute to get as much of the warp out of the ribs as possible (here I had to spend much more time getting them as close to flat as possible--on some ribs I never entirely figured out how to get both the top and bottom of the ribs completly flat at the same time). Once my ribs got into the skin, all the flanges seemed to rest pretty flat with the skins, so I think my "minimalist" method worked pretty well.

I did not then go back and try to re-bend the flanges. I don't think the goal is to get a perfectly flat/perfectly flanged rib when you're done--I think the point is to get the ribs straight ENOUGH so that you won't have a terribly hard time matching up the holes in the skin to the holes in the ribs. Once clecoed to the skins, the the skin will help straighten the ribs out the rest of the way.

Hope this helps.

Steve

[RudiGreyling]

Thanx Steve...it is onto bending 90 degree flanges I go.

While we on this topic, it seems there is a bit of an art to get those ribs flat during fluting (based on reading Steve's post)

Any backmagic or art invovled with fluting those main wing ribs?
What works best for you, so i can learn?

Thanks
Rudi

[Captain_John]

Rudi,

I fluted all the rib (side) flanges and "90 degreed" the base flange several times. Once to get it all figured out and another time to check my work.

Flute and 90 all of the ribs, stick them in a pile and re do them. Since this is my first attempt at airplane building, I found inconsistencies in my techniques and subsequently... my results.

I then was able to go over all the ribs and make them better in my own opinion.

If I'm reading you right, are you trying to square up the curved (top and bottom) flanges?

Don't even try that. They will true up once assembled with the skin.

Hope this helps!

CJ

[RudiGreyling]

This QQ (quick query) is becoming a long query

John, I am confused now , I thought the idea was to get all the flanges 90 degrees, in my drawing below all the coloured arrows.

Are you saying it is not worth bending the blue and red arrows 90 degrees since the will line up? Are you only doing the green arrows

[sf3543]

If you want things to fit correctly, you do need to flute and bend the rib flanges as close to 90 degrees as possible.
It can be done with a little patience and everything will fit a lot nicer later on. Trying to force things in to position is a recipe for disaster, or at the least, a poor fit and problems that will be visible from the outside of the skin.
Here's a good sequence for getting the job done:
Deburr all of the edges, especially all the tabs around the nose of the rib. If you do it later, you might mess up all of that bending and fluting you did.
Make sure you have a FLAT surface, like maybe a piece of glass, to set the rib on while you are doing the work. You'll need a fluting tool and a seamer, as well.
Begin by fluting the flanges to get them as close to 90 degrees and the rib as close to flat as you can. As you go along, lay it on the glass, flanges up, to verify how flat the rib really is.
Keep at it...if you flute an area too much and the rib bends up a little, just take a seamer and squeeze the flute back out a bit and the rib will relax.
Patience is the key here and it will take a while; however, a good job here will make for a better fit in the wing, it will go easier during assembly and it will look a lot nicer from the outside after the job is done.
Good luck.