fluting and seaming

prestwich · Post by **prestwich** » Fri Feb 24, 2006 4:47 pm

OK, It's time to get serious about this! I'm running out of excuses to procrastinate.

I want to forge ahead with this silly horizontal stabilizer, but I'm still confused about fluting and seaming. I even called Van's, and now that I reflect on what the guy told me, I'm still not sure. I think he said that there really wouldn't be much need for those things on the HS ribs.

I believe he said that, on the wing ribs, fluting the flanges straightened out the web. Is that right? So if my webs aren't warped, I don't need to flute? What about seaming? Is that done to make the flanges more perpendicular to the webs, or to straighten out the waviness of the flanges, or both? Doesn't a seamer inadvertantly flatten out the curve that's supposed to follow the airfoil shape?

Which hand seamer are you guys using? Mine seems a bit clunky, and the jaws don't really come together flat except at the very tip.

I guess I'm feeling a little intimidated by my complete lack of understanding of these two processes, and wondering, when I pick up a rib, what I'm looking for, and how to prep it for assembly. Any pointers you guys can give me would be appreciated!

Jon
7A emp parts gathering dust.

avaviat · Post by **avaviat** » Fri Feb 24, 2006 5:23 pm

When Van's formed the ribs they wound up with flanges that flare out slightly. If left that way, they'll put an S-bend in the skins (raising the skin on the flange side, which will lower the skin on the other side), which will be ugly. So take the seamer and bend the flanges until they will be parallel with the skin or whatever they attach to. For example, the flanges that attach some of the HS ribs to the foreward spar (which is angled back) should not be 90 degrees to the web -- if they are, the rib will point in the wrong direction when riveted/clecoed, which makes putting the skin on difficult. You aren't trying to re-shape the curve of the rib, just to make sure the flange is parallel with whatever it mates to.

Once that is done (well, even before it is done, but especially after) there is another problem. The flange is actually shorter on the web side than on the open side. If you take a flexible ruler and hold it against the flange, you'll see that it curves off towards the web. You'll also see (with a bit of fiddling) that the web edge is maybe 1/4" shorter than the outer edge.

By putting vee-bends in the outer edge of the flange, you effectively shorten that edge. This pulls the web straight, and makes the holes all line up properly.

That's all you are really trying to do with it.

BTW: As far as seamers go, I have two. One expensive ($35) cleveland offset hand seamer. The other is a cheap ($2.99) Harbor Freight "Flat Jaw Welding Pliers" ... the HF seamer had to be seriously cleaned up because it had sharp edges and the like... but both work.

BTW: I didn't use a jig for my HS, but it might have been easier with one as a work...surface, I guess you'd say.

cjensen · Post by **cjensen** » Fri Feb 24, 2006 5:56 pm

don't make a bigger deal of fluting and seaming than it is...they work together to straighten the ribs out. if you over flute, seam it back. use the seamer to 90 the flange to web bend. you're not bending the metal far enough to work harden or anything. just use the tools to make the ribs lay flat on the table, and they're done.

jim_geo · Post by **jim_geo** » Fri Feb 24, 2006 9:30 pm

Exactly what Chad said. Eye ball the flange if it's close to 90 leave it if not bend it a little till it is. Then the fluteing tool is used about every other rivet hole or so, as needed to make the rib lay flat. Close counts on all this.

prestwich · Post by **prestwich** » Fri Mar 03, 2006 12:21 am

YES! I've seamed and fluted a couple of HS ribs now. Thanks to all for your explanations and encouragement.

Besides not having built an aiplane before, I know that part of the challenge for me is overcoming perfectionism. (I was the guy in school who went home with head hung in shame if I scored a 99 on a test instead of 100.)

jim_geo · Post by **jim_geo** » Fri Mar 03, 2006 1:46 am

Oh man! This projects gonna drive ya nuts. But I bet you'll have a nice plane when you're done

.

cjensen · Post by **cjensen** » Fri Mar 03, 2006 9:24 am

way to go pwich!!

Wicked Stick · Post by **Wicked Stick** » Sat Mar 04, 2006 9:52 am

Might I suggest that in addition to the groups help, you seek out an EAA chapter or someone else nearby who is building an RV.

Reading instructions and verbal help is great, but actually watching and learning and doing it with someone who is experienced would really be ideal.

Before I even started building anything, I visited a couple of RV builders projects and spent some time helping them. It was a great way to learn some basics. Also, the Orndorff video on tools and procedures is helpful to some extent.

I have a couple of new found friends who are also building RV's (Captn John, and Rob E.) and we take turns helping on each other's projects when needed.
To me, it makes building so much better and productive. Plus, it will be great fun when we all start flying to places together.

prestwich · Post by **prestwich** » Sat Mar 04, 2006 11:00 am

Who needs help? This airplane building is duck soup. Seriously, those are great suggestions. I've got the Orndorff videos, but I can't watch them. The production values are so bad that I just can't sit through them. And, they predate the punched hole kits, something I didn't even realize the first five times I tried to watch, so much of what's in there doesn't apply any more.

EAA is a great organization. Here's my sad story about that: I joined my local chapter and found that no one here is building anything. Then, I joined a chapter 125 miles away, where my girlfriend lived, and met some fantastic guys. Many active RV builders, and many generous offers of support. And, she was eager to be my chief rivet bucker.

But, at that time, I hadn't acquired my tools and really gotten started. Then, unfortunately, we split up, so driving that far to attend a meeting or hang out at the airport for an hour and ask questions just seems like too much.

But I'll get there, thanks to you guys, and I'll keep looking for some other builders close by. Meanwhile, now that I'm an expert fluter/seamer, it's back to work...

captain_john · Post by **captain_john** » Sat Mar 04, 2006 7:02 pm

Re: Inactive EAA Groups...

Yah, I can relate! In the Plymouth, MA area there was only one group. The EAA Ultralight group Chapter 62 when I started getting involved.

I was quite honestly, less than impressed when I joined because no one was really working on anything and if they were... it was an ultralight.

Fast forward 3 years to today. I am now Vice President of the group and Wicked Stick is the Newsletter Editor and pressman. We are using the group for RV stuff and calling it UNLIMITED instead of ULTRALIGHT!

I am not sure what the future holds for little Chapter UL 62, but they now know what an RV is!

CJ

Dan A · Post by **Dan A** » Sun Mar 05, 2006 3:49 pm

Way to go CJ! Make that chapter into a real EAA group!
Dan