Leading edge and fuel tanks...

[terrye]

Yes, the tank skins are a tight fit on the tank ribs. I clecoed most of the bottom prepunched holes then I used some ratchet straps and blocks of wood on the aft side to help insert the ribs into the skin. Also used a scratch awl through the skin and rib prepunched holes to lever them into position to make it easier to insert adjacent clecos. After I had drilled the skins to the ribs it seemed to go easier next time through after I had dimpled the skins and ribs.

My tanks also took about 100 hours but a lot of this was learning how to use Proseal (thought I was going to glue myself to the wall a couple of times) and being very fiddly in making nice beads and cleaning up.

[blueflyer]

I agree, those tanks are a big mental hurdle. Its just sooo slow and tedious type work. You do have a good sense of accomplishment once you get them done though. Keep at it.

[nilberg]

I have somewhat different experience. I might have bee lucky with the rib batch I guess. I have to admit, I have only done the left leading edge and fuel tank. I thought I must have done something wrong, because my rib had a very good fit. I noticed small bulges on the bottom leading edge part due to pointy ribs, but both the leading edge (finished) and the fuel tank went together smoothly both before and after dimpling. I found the leading edge much easier than the empennage because of the ample room to rivet.

Timewise I have spent a century for all the fuel tank fittings (vent line, clips, anti hang-up, etc.).

Getting the leading edge riveted and the hole proseal thing is another matter, but I am ignorant enough to look forward to it......

[Flyin'Bryan]

Originally Posted by terrye

Yes, the tank skins are a tight fit on the tank ribs. I clecoed most of the bottom prepunched holes then I used some ratchet straps and blocks of wood on the aft side to help insert the ribs into the skin. Also used a scratch awl through the skin and rib prepunched holes to lever them into position to make it easier to insert adjacent clecos.

I wanted to bump this thread a bit because I am dealing with exactly the same situation that everyone else has. Aaron, you said you were going to contact Vans to discuss this but I don't believe I saw a response posted here. If there was one I would love to hear what they said.

I bought two new strap-only ratchets with no hooks and I plan to do the same thing and will post pics of my results. I had already filed and scotch brited my tank rib LEs to smooth out the bumps per Vans instructions, and I am satisfied that the rib flanges are the way that they need to be for a smooth fit.

I started on my left wing tank with the skin in the cradle. I found it easiest in my case to line up and cleco the top side of the ribs first, from LE to the rear. This went fine for all the ribs. Then I experienced no less than a 1/4 inch or more gap between the LE of the skin and the nose of reach rib. I immediately had the feeling that the tank skins were not bent as well as they should be. Personally I think this is a result from a combination of the way they are bent at the factory, and they way they are stacked together with all the other LE skins and highly compressed and taped together for shipping. Just a guess....

I too then tried my best at 11:00pm at night, after spending several hours prior to this on Z bracket prep and back drilling holes, to apply mass force with one hand on the rear flange of one rib, with a cleco in the cleco pliers at the ready in the other hand. While trying to insert the most forward cleco at the front of the LE edge skin, it was a "wonderful" feeling when I felt the cleco give way, scraping the skin for about 6 inches or so. I still have the vinyl on the exterior of the skin, but I know what I will find when I get enough courage to remove it to see how deep the scratches are. I said many choice words, threw the damaged cleco on the floor in disgust, and went to bed.

So I should have quit working before attempting this, because I was already tired. But you all know how it goes - why stop building when you are on a good roll, right?

Anyway, I could tell that the tank skin LE seemed to "want" to conform to the tank rib when I applied enough pressure by pushing up on the LE of the skin with one hand, and pushing down on the rib rear flange with the other. Problem is that I ran out of hands at that point, so I had none left to insert a cleco into a hole once they lined up.

So I have thought about this for a couple of days, then I found this post, and came to the same conclusion that ratchet straps should be able to wench down the ribs enough to line up the holes. I consider it a kind of reverse process from using them to wench the LE and tank assembly down on the main wing spar. This time you use them to force the tank ribs and skin to conform to each other and line up the rivet holes.

Now the only thing I need to consider is if I should try this with the skin in or out of the cradle. It definitely seems like the cradle is preventing the tank skin from forming around the rib, but I had no such problem with the outboard leading edge assemblies. They all went together in the cradle just fine, but were also a little tight the first time.

Wish me luck, and I'll report the results of the process with pics.

[wjb]

Good luck! I had a heck of a time getting everything to line up properly. I would not have believed it possible, except for the fact that 100's of others have done it with the same pre-punched skins. The first time together was frankly, heck. The second time was easier. By the time I actually slathered on the pro-seal, the tank went together relatively easily. Keep at it! It's very doable (but maybe not doable without some choice vocabulary)

FYI, I did it ultimately out of the cradle .. I built a nice one, but it didn't really help me. The bench top was my best friend.

[aarvig]

Check your PM's

[PIN 37]

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?

I cant agree with the other posters here, to me there is something wrong. yes they are a bear to fit, but there should not be the level of pain as described by you. take a picture and send to Vans for advice. The fact that you are deforming the outer skin raises flags for me. Many RV's have been built, including mine, without deformation of the outer skin. Please consult Vans.

[aarvig]

Originally Posted by PIN 37

I cant agree with the other posters here, to me there is something wrong. yes they are a bear to fit, but there should not be the level of pain as described by you. take a picture and send to Vans for advice. The fact that you are deforming the outer skin raises flags for me. Many RV's have been built, including mine, without deformation of the outer skin. Please consult Vans.

Assembly instructions are incorrect...simply put, the skin should not be placed in a cradle. The skin should be opened, rib clecod by the most forward hole on the bottom, flipped and cleco'd on the top, then cleco the whole thing. This was verified by a conversation I had with the top brass at Vans. I was told the assembly instructions would be updated accordingly.

[Flyin'Bryan]

Originally Posted by aarvig

Assembly instructions are incorrect...simply put, the skin should not be placed in a cradle. The skin should be opened, rib clecod by the most forward hole on the bottom, flipped and cleco'd on the top, then cleco the whole thing. This was verified by a conversation I had with the top brass at Vans. I was told the assembly instructions would be updated accordingly.

Got the PM and also glad you updated this thread. I'll take them out of the cradle and work them as you suggest. I guess all I can do is try to laugh this off when I think about how a fairly sizeable number of us, as shown from this thread and many others, have all had to deal with this problem to one degree or another. For me the next steps were clearly to use the straps or take the tank assembly out of the cradle, so I'll try the latter and see how that goes.

[longranger]

Check the third paragraph on this page of my build log to see how I made it work. (Hint, yes, you DO start without the cradle.)