Leading edge and fuel tanks...

aarvig · #1 03-30-2014, 06:34 PM

Well, I need to go to confession. I have said every word under the sun the good lord regards as foul. I have posted regarding the leading edges before but now I am posting regarding the fuel tanks. Am I the only one who feels the leading edge/fuel tank skins are not bent properly? The only thing that will make the ribs fit is if I shave the snot (round off the rough edges) out of the leading edge of the rib flange and then straddle the LE or Fuel tank skin and then lay all my body weight into the rib to get it into place. That being done the inside of the skins have been throughly mangled to the like that I've never seen before and the ribs have been bent several times (at the front and the rear of the rib) to the point that I'm concerned about their structural integrity. When everything is in place the ribs are still bent/bowed under in front (in the direction of the flange) and I have a 1/4 inch gap between the bottom leading edge of the rib and I have some ridiculous dents on the surface of the leading edges. Am I the only one suffering with this? It can't be normal is it?

blueflyer · #2 03-30-2014, 06:51 PM

my 7 fuel tank ribs were very snug going in (pre proseal application) but not to the level of difficulty that I am interpreting in your post. It almost sounds as if something is a little off somewhere. Could they be inserted upside down??

I believe vans recommends a certain method to clecoing the ribs in place in order to make it easier to get them in place. I think they recommend to start clecoing from the leading edge and move rearward, but I cant recall for certain.

bruceh · #3 03-30-2014, 06:58 PM

They are toughto line up and cleco. Go ahead and round off the leading edges of the tank ribs. There really isn't anything structural going on there. The eventual bend in the skins keeps it rigid. Every time you put this together and take it apart it will get a bit easier. With the proseal on, it helps it to slide into position easier. You are using the cradle to hold the tank skins? Do a few clecos on the forward holes and work your way back.

wirejock · #4 03-30-2014, 07:14 PM

Mine were tough the first time but not like yours sound. There should not be a gap that big anywhere or deformation of the rib. They might be bent wrong. Vans makes errors occasionally.
It's not uncommon to clean up the ribs a bit on the leading edge end and they usually need quite a bit of tweaking to get them fluted and flanges at 90 degrees.

My technique for assembly may not be correct but it worked for the leading edges and the several assemblies of the tanks before they were sealed.
Install the ribs to the bottom of the skin first with every other cleco. Leave out the first cleco in each rib for now.
Place the part on a foam pad leading edge down.
Get some help and push the top skin against the ribs till a cleco or drift pin can be inserted I to the middle rib, middle hole. Watch the ribs. They may need to be coaxed a bit. While holding the leading edge in place, insert clecos in the same hole to each rib.
From here it should go easy. Insert the trailing edge hole clecos.
Insert clecos between the leading edge hole and the middle hole clecos.
Work toward the leading edge inserting clecos till you get the first holes in then put the others in.

It gets easier each time. I did the tanks by myself when I prosealed them.

Vlad · #5 03-30-2014, 07:23 PM

All good advice here. You are not alone Aaron welcome to the Club of Dents I am the President.

Mine were extremely distorted. I filed I adjusted I bent I rebent I cut fingers I cursed and so on... the tanks were eventually done and are still holding advertised gallonage. Don't worry about the dents the painter will fix it

Joe Parish · #6 03-30-2014, 07:44 PM

Aaron
I had several spots on my leading edge that had bulges in the skin from the ribs. I kept running that edge over the scotch brite wheel removing material. I had two or three ribs I ended up re-ordering due to what I felt was a removal of to much material and they still bulged the skin. What ended up working for me is a combination of the 3M wheel for removing some material and I made a wooden template of the shape of the leading edge. I would set the rib over the block and reshape the leading edge a little. The edge of the rib where it transfers from the flange to the web seemed to be where all my problems stemmed from.

As the previous posts have said the tank gets easier each time you put it back together. I remember the first time I really struggled with it. I believe I did the same on the tank ribs if my memory serves me.

543TB · #7 03-30-2014, 08:03 PM

There was a lot of cursing and more than a little blood involved in ours. Some people will say it is easier to start from the nose with the clecos and work back, ours was the other way around. Definitely spend some time with the fluting pliers, and the regular pliers... some of our nose tabs weren't bent in enough. Not the easiest parts to put together, for sure.

wjb · #8 03-30-2014, 08:05 PM

+1 to Larry's post .. I did mine in a similar way. Doing a thorough job smoothing the tips of the ribs is important to get them to somewhat slide. For a few days, my only source of inspiration is that *all* those other RV builders did it, and I can too. Kinda like those wire puzzles; once you know the trick it all sorta worked. I did not believe that this could be done with proseal in place. In the end, it all went together easily.

Perhaps if there is an experienced eye around that can see if something's malformed? The gaps seem out of place; mine were tight.

As for confession.. say two Hail Marys, have a beer, and try it tomorrow.

rvbuilder2002 · #9 03-30-2014, 08:12 PM

Be sure you have read and understand the RIB FLANGE FACETING portion of Section 5 in your construction manual (chapter 5.2)

sbalmos · #10 03-30-2014, 08:56 PM

Oh you have no idea Aaron. It's a perennial point of cussing and drinking it seems. Like others have said, it seems to get better as you fit things together multiple times. I also had to "put my weight into it" the first two or so times I was fitting everything together, and ended up bending quite a handful of clecos. I think I said more than a handful of choice words as I was tapping in the doubler strap on the inboard (non-predrilled) rib of the leading edges.

My inner skins were equally mangled and scored up. But nothing a bit of primer or proseal wouldn't cover. And read through the other leading edge threads here. A lot of people believe the nose flanges of the ribs are underbent, not the skin. I know I rebent a few of them. Between that and some passes on the scotchbrite wheel, I imposed my will on them, and they finally succombed.

Build on! Enjoy the fact that you're back to building.