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radius of vertical stabilizer ribs

J

JRo

Well Known Member
I've had the skin of my RV-12 vertical stab on & off several times withe clecos, each time removing more material from the skinny end of the top and mid ribs to eliminate distortion of the skin as it's drawn tight to the skeleton. I'm there or almost there now, but I've gotten down to where the 1st pre-drilled rivet hole on each (of 2) ribs is compromised. Doesn't look like I have space for a substitute rivet on what remains of the flange at that spot. Obviously, there will be a "dummy" rivet head there for appearance on the finished skin, but am I OK without the forward most rivet on the center & top rib(s) of the vertical stab? Suggestions?

Jim
RV-12 newbie
empennage 10%
 
You are removing material to the point that the pre-punched holes don't line up? Or, you have removed the material that the holes were in? Did you flute the ribs?
 
Jon,

Thanks for response. Yes, ribs were properly fluted. But, in the process of removing material from the ribs enough that there was no distortion of the skin when drawn tight,, it was necessary to grind the flanges on the skinny end of both ribs right down to the 1st rivet hole on each of 4 flanges. Holes line up perfectly between skeleton and skin. Just can't place forward most rivet on each rib...no hole in rib.

Jim
 
Whoa, Jim, this doesn't sound right. I don't remember having to remove any material at all. Your question regarding the structural integrity is one for Van's support line, not for one of us. Call me if you wish. I'll be around the airport all afternoon.

John
 
If I'm correct in interpreting what you are saying, the "skinny end" is the leading edge of the ribs. I wouldn't think not having these four rivets missing would cause a critical loss in structural strength. Ultimately, give Vans a call. I don't remember removing any material from those ribs, just fluting.

However....

You are in the beginning stage of assembling an aircraft that will, potentially last longer than you will be alive. Please be careful with your building techniques. Sure, a couple of rivets probably wont bring the plane down but one here, one there, they will start to add up.
 
John,

Absolutely! I agree completely. Care, craftsmanship, and attention to detail are my goals. And yes, I have e-mailed Vans for tech assistance here. I cleco'ed and removed one side of the skin from Vertical Stabilizer 2-3 times. Each time, as the skin tightened against the skeleton (yes, leading edge) the ribs began to deform the skin slightly (too much material, or not enough radius) on the skinny (leading edge) end of top 2 ribs. Now, as I say, the fit is good, and holes all line up nicely, but the forward most rivet hole in the flange of the rib(s) is not valid.

Thanks again,

Jim
 
JRo said:
the ribs began to deform the skin slightly (too much material, or not enough radius) on the skinny (leading edge) end of top 2 ribs. Now, as I say, the fit is good, and holes all line up nicely, but the forward most rivet hole in the flange of the rib(s) is not valid.
Click to expand...

I faintly remember that I had a problem with that too. I removed quite a bit of material but eventually when reaching the point where I got close to the rivet hole in the rib, I decided to leave a slight deformation in the skin. I was only visible right at that rivet hole in direct reflection of the shop light.
 
Exactly right. I think I went one small increment farther than you did on the radius of the rib(s) in order to have no dimple at all in the skin. The fit is now perfect, and hole alignment perfect as well. But, as I say, the new edge of the flange is so close to the first rivet hole that I consider that rivet invalid. Waiting to hear from Vans...

Thanks again,

Jim
 
Rib flange doubler

A flat strip of aluminum 1/2" wide could be used to reinforce the rib flange (if necessary).
Joe Gores
 
I wonder if this is something that got changed along the way. My kit Nr 461 had no such problems at all, on mine it all fit perfect like most everything else Vans makes.
 
Jim,

I went to the hangar yesterday and checked my VS. It has one tiny bulge, not noticeable unless you look at it from exactly the correct angle. I guess I should have cut back the rib more, as you are doing! Checked Page 06-07 and the instructions do say to "adjust" the ribs. I had forgotton about that, so I checked my build log, which says "Re-contoured rib end tabs." So I guess that means my long term memory is going!

As long as you still have a hole for the rivet to set in, I think you will be fine. Most of the strength of the structure is in the skin, and that hasn't been compromised.

John
 
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