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Fluting for the sake of Fluting????

O

osaleh

Active Member
hi all,

i am at the part where i have to prep HS 404, 405, 706,707 and 708. The good manual says to flute. Every thread i read in this user forum says the result should be holes need to align and web lay flat on surface while the flanges face up and are at 90 degrees. THe only issue is, my ribs listed above, do that w/o any fluting. They lay straight and when i look at the holes down one flange, they line up.The flange also seems to be at 90 degrees to the web. So, since everyone flutes and i was feeling left out, i fluted one of my ribs to try out. Now after fluting, it bends up. i took most of the flute out to get it to settle down once again. Did I miss something here???? I am sure there will be a time in which i will get a rib that is bent and will need a flute. However, did you guys have similar experience with the above mentioned ribs?
 
Hi,
in the forming process of ribs, they usually come out with some bending in it (much more noticeable on wing ribs). Fluting is needed to line up the holes on the rib flange. So, if your flange is at 90? with the web and the holes are in line (use a straight edge to verify) then fluting is not needed.
 
Some people will say no - no need.

For my wings, I fluted everything that had to be fluted in between every rivet hole. I found that it was easier to work towards a flat and square rib from a fluted one using the seam bender than to guess which rivet hole needed fluting.

I'm sure part of me was doing it to make them look pretty, but I did cleco my wings together and measure washout to less than a 0.5mm graduation on both wings, so it wasn't in vain (I tell myself)
 
Rick6a said:
Three words...... Flute as required.

BINGO!

The ribs in my tail kit required very little fluting. The wing kit has been a different story. The tank ribs, in particular, have needed significant fluting to straighten them out. However, I only place flutes where they are needed to flatten the rib and align the rivet holes. I've yet to find a rib where I had to flute between every hole.

If you over flute, and the rib starts to bend in the opposite direction, just flatten some of your flutes using pliers or a seamer.
Click to expand...
 
Here you can see what fluting accomplishes.
A stack of 8 pair of ribs on the left are fluted.
A stack of 6 pair on the right have yet to be.

vidx8p.jpg


When you get to the fuselage bulkheads, you can flute to 90 degrees and then back them out when the top skins go on because of the shape of the fuse. (narrow body at rear to wide front)
 
The early kits provided fluting guides...

The plans actually showed where to flute the ribs. You laid your ribs over the full size plan and fluted at the line. They where not between every rivet, nor do they need to be. Not that much extra work to do it, but not necessary to get a straight rib.
"Flute as required"... as previously stated. Nobody is going to tear your wing or empenage apart to inspect your flutes.
I believe Vans ribs are formed from tempered material, not put into "W" and formed. This leads to more deformation due to forming.
My Fiat ribs have no fluting. The flange was designed with a return that straightens the rib. They would have been put into "W" then formed. It is simply not cost effective to do this on an RV, so we flute.
 
yeah can easily get a rib straight most of the time with half of the flutes shown in the pics above, not to say that my way is better, just saying that it wans't necessary in my case
 
My ribs looked liked yours when I just examined them. When I cleco'd everthing together the need for fluting became obvious. Not much fluting but some.

Just one data point.
 
I have a slow build six kit.

I copied the wing rib fluting diagram onto a nice flat piece of plywood and marked where the suggested flutes should be made.

I put two leftover long 3/16 rivets in the plywood sticking up through the wood (after filing the heads off) where the tooling holes were put in at the factory. Then I set the rib flange up on the flat plywood.

Flute away at the marks, start out slowly and you will see the rib lay down flat on the wood. If you over flute you can somewhat undo it by squeezing the same place you fluted with some smooth duckbill pliers.

Once you get the hang of it, they will be flat and fit well.
After the first few I got pretty fast at it.:cool:

PS. I used the hand seamer to get the flanges at the right angle.

Best wishes on your project.
 
great image

Onperdiem said:
Here you can see what fluting accomplishes.
A stack of 8 pair of ribs on the left are fluted.
A stack of 6 pair on the right have yet to be.

vidx8p.jpg


When you get to the fuselage bulkheads, you can flute to 90 degrees and then back them out when the top skins go on because of the shape of the fuse. (narrow body at rear to wide front)
Click to expand...

Great image. tells all. I am still working on the Empennage and the short ribs require little to no fluting. However, i can see the long ones in your image. Makes the point clear. Thank you.
 
We're showing our "old school" ways....

GAHco said:
I copied the wing rib fluting diagram onto a nice flat piece of plywood and marked where the suggested flutes should be made.
.
Click to expand...

I dont think they provide a fluting plan on the newer prepunched kits. "In the old days" (ha!) we where spotting our own holes and you had to be careful where you put that flute. On the new kits, the holes are already done so you dont need to worry about putting a flute where you shouldn't.
These new kits sure take a lot of the "fun" out of the process don't they?:D
 
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