Fluting Rudder stiffeners?

Building my 7 Time Machine........

I have all my Rudder stiffeners trimmed and ready to go but they have a bow in them like a rib would and don't sit flat on the skin. I see some build sites that have no flutes and some that have flutes on both flanges. I'm paranoid that the thin rudder skin will take the shape of the bowed stiffeners. In my mind I wouldn't want to put a flute (kink) in the vertical rib (no holes) used to stiffen the skin. Maybe after dimples and rivets everything will be flat? What say the masses?

I did search on Rudder stiffeners but didn't see much on this particular subject.

Flute

Which way are they bowed? Photo please.
I didn't need to flute mine.

Haven't sorted out pics yet. If I set them in place on the skin the center of the stiffener rides up off the skin. The middle of the longest one rides up a good 1/8th inch off the skin. They cleco onto the skin easy enough. Just wondering if they will suck the rudder skin in if I leave them that way and finish building.

Flute

If they are high in the middle, flute them. You want them to lie flat. Sometimes dimpling makes them bend.
1/8" is not much. My guess is a few tiny flutes will bring them down. Try one.

I went way over the top. I match drilled mine to a particle board then after prep work, prosealed them to the skin with clekos on the board and left it for a few days before riveting.
Did the same with the elevator stiffeners.

Same thing...

Well I saw the same result when fluting my rudder stiffeners. The longer ones bow up about 0.100”. What is the conventional wisdom on fluting the side of the flute opposite of the side with the holes? This is the side of the stiffener that carries the compressive load when the skin is compressed. At that point that section is in compression, in which case generally you don’t want a zigzag shaped member, right? Am I over thinking this? Do I just put a lot of very gente flutes in them and assume that small bend doesn’t reduce strength significantly?

Anyone?

Anyone else have any suggestions?

There is no reason a simple angle has to have any bow to it. If they do, manipulate them with hand seamers or reform them over the edge of a board.
They should straighten easily.
However, you started with a straight piece of angle, no bow right? So, somewhere in the process they get bowed. You can fix that.