Blessed stinking tail cone ...

[Spike]

I have been working for multiple nights on getting the tail cone fitting together properly and it is driving me nutz!! More specifically I am really doubting it can be done.

Am I the only one that has had this problem? The basic problem is that once everything is together and I get it plumbed up, and clecoed up the horizontal pre-punched holes on the thick bottom tail skin dont completely match the holes in the side skins. The last 6 holes in the bottom skin on each side are low by 2/32"

Everything looks fairly true, the F-711 & F-712 bulkheads are sitting pretty tight against the bottom skin, I just cant seem to get that tail piece up high enough in the back to make it all work.

Thoughts?

[TomNativeNewYorker]

without pics, I am not sure how far off you are.

are the holes far enough off that you can plug the holes(installing double flush rivets) and relocating to another location without drilling into the plugs?

[Spike]

Not really. As a matter of fact the majority of the ones I am talking about would generally be elongated. For a few of them I could just go up to a #30 and be done with it, but not all. I'm just frustrated I guess.

Spike

[Midnight Sun]

There is no problem that cannot be solved with the suitable application of high explosives.

[TomNativeNewYorker]

If the skin is thick enough to accept a 1/8th rivet countersink without problems, pull a nike and 'just do it'.

[cjensen]

This is a VERY common issue Spike...mine was like yours, Brad had one that he couldn't even use, and ordered a new one.

I drilled the holes to 1/8 and haven't looked back...

[cnpeters]

Add me in. Those last holes ended up as figure of eights. Had to order a new one from Van's.

[Brantel]

I also did drill mine to 1/8" and bent the sides up slightly to help.

[Spike]

I got it as close as I could get and then drilled to 3/32". Once I pull the tail apart I will look at the holes. If the elongation is too bad I will reassemble and go to 1/8th" drill bit. In the mean time I am moving forward. I have already spent 2+ nights working on this thing.

Spike

[airguy]

I had the same problem, and a couple others have as well. Turns out the problem is that the 711A and 711B bulkheads are reversed in the plans. Swap them A for B, reassemble, and it will come out fitting just right.

I found this out too late, was frustrated with the poor fit, and ordered a new unpunched tailcone skin and made it fit - then after I had set a few of the rivets I found out where the problem was from another builder and felt pretty silly for not catching it myself.

[Thermos]

Ok friends, I'm having the same problem - I think. I'm trying to cleco the 711 and 712 bulkheads onto the lower tailcone skin, but there are a couple of holes on each side that just don't match and are waaay off. Are the 711A and B bulkhead parts *really* reversed in the plans? I can't find any plans revisions on Van's website that show this.

And if anyone else has any hot tips on getting these things to line up, I'm all ears (or eyes)

Dave

[Spike]

I ended up punching a fair amount of the rivets to 1/8" in that rear bottom skin. Ultimately it all ended up well, but I really had to work the bulkhead flanges. It took a few days to get it together. You probably won't get to the point that you are really happy with it, but you will get it to the point that its sound.

I was able to get all of the holes to be visible through the skin close enough that a 1/8" bit made them all work.

Spike

[Thermos]

I was able to get all of the holes to be visible through the skin close enough that a 1/8" bit made them all work.

Were you able to get clecos in all the bulkhead tabs before you clecoed that whole assembly to the side and bottom skins? I have a couple of holes that won't line up even to the point of getting a cleco in...

I've been tempted to work those tabs down with scotchbrite or a file in the way Vans recommends for the wing leading edge ribs. But since those bulkheads are important (only from a structural point of view ) I've resisted that temptation.

Dave

[Spike]

Actually I was. My problem was that once I got the bulkheads fitted to the bottom skin, and tried to get that assembly into the rear fuse, the horizontal holes did not line fully up with the horizontal line in the fuse skin.

This got worse towards the rear. Ultimately one of the things I had to do was to take my time and work through every stupid tab in the bulkheads, trying to get them to allow the bulkhead set lower. This was only somewhat successful.

Realistically, at some point, I got fed up, went upstairs to cool down, and then came back later with a 1/8" bit and made it all work. Not all of the holes were perfect but I made it work. This was one major area of indoctrination where I was forced to learn the difference between ideal, and workable.

Spike

[airguy]

Ok friends, I'm having the same problem - I think. I'm trying to cleco the 711 and 712 bulkheads onto the lower tailcone skin, but there are a couple of holes on each side that just don't match and are waaay off. Are the 711A and B bulkhead parts *really* reversed in the plans? I can't find any plans revisions on Van's website that show this.

And if anyone else has any hot tips on getting these things to line up, I'm all ears (or eyes)

Dave

It's never been confirmed on paper (or corrected on paper) by Vans, but several people have reported verbal confirmation from Vans on the tech-help phone line that this is the case. I can only tell you to reverse them yourself and see if it fits better. It's too late for me, I ordered an unpunched tailcone skin and did it the hard way.

[dons]

I too had issues putting this part of the fuse together, but found a couple of things that made a huge
difference.

The first was to pre-bend all the flanges on the bulkheads to the proper angle, especially important on
the F-711 and F-712. If you leave them at the angles as supplied, getting it together is near impossible.
To do this I made a set of angle reference blocks which allowed the angles to be easily repeated. On
the F-711 and F-712, the aft facing flanges needed some rework to prevent interference when they
were bent at the proper angles, the forwarded facing ones just needed the normal edge finishing.

• typical bulkhead flanges on the F-711 / F-712
• typical bulkhead flanges on the F-711 / F-712
• set of angle reference blocks in one degree increments

The second task that enabled the rear part of the tail cone to go together as it should was to make
adjustments to the F-779 skin itself. As supplied in my kit (and I suspect it may vary a bit) the bends
were way under done to allow the area to fit together without excessive effort and force. If there is
one thing I have learned in putting together this kit, it is that the pre-punched holes are almost always
in the correct spot and issues occur because of bends being in the wrong place, a wrong radius, a
bend just way off in angle, or a curve that just isn't bent enough. With my F-779 the issue was the
curved bends were just no where enough.

The F-779 is a thick piece so it takes quite a bit of work to get it bent properly, but once done the
F-712 and F-711 flanges lined up almost perfectly once their flanges were bent to match the angles in
the area.

• example of how the angle reference blocks were used
• the F-779 skin after bending
• partially riveted problem area

Get the parts bent so that all the holes line up without force is where the effort went on this one, but
then the whole thing went together easily. I fully admit I tried to cleco the area together before doing
the mentioned steps, and it was almost impossible, required way too much force, and not all the holes
lined up.

[BSwayze]

I agree with you, Don,

I spent quite a bit of time with these parts on the bench, making sure all the flange tabs were at the correct angle before proceeding. I also corrected the interference that you noted on some of the flange tabs by trimming them a bit. This is time well spent. I put it all together on the bench first. That helped immensely later on when it all goes together in the aft fuse:



Use an ice pick or an awl to help line up the holes for clecoing, and use a cleco in every hole. Keep adjusting the tabs and flanges if needed. My skin needed more bending to it, too, but it all went together just fine. Take your time with careful prep work on these parts and they will go together just fine.

Later, when you put it together with the aft fuse, use a cleco in every hole and the ice pick to help:



I used a clamping method outlined on my web page here. This really pulled everything together nice and tight for drilling:

http://www.europa.com/~swayze/RV-7A/Fus ... 81221.html

I pulled one cleco at a time to drill them to full size, then put the cleco back and move to the next one. This is a slower method of drilling, but for tight places like this it pays off.

Later on, after all the prep work, some of the rivets can be installed on the bench:



I would have used 1/8" rivets in a heartbeat if it was necessary here, but it turned out that it wasn't necessary in my case. YMMV as they say, and that's okay. Here it is all riveted together:





I hope this helps someone going through this phase of the build. Hang in there; you'll get past this point before you know it.

[Thermos]

Wow...just got back from St Louis and this thread kinda took off while I was away! Thanks Spike, and big thanks also to Don and Bruce for all the pictures. Gives me hope that I can get at least an acceptable fit on those bulkheads.

I started bending longerons before I left, hopefully that'll be done by the end of the week and I'll be back on the tailcone...as CJ would say, "nothing to it but to do it!"

I owe you all a at Oshkosh next year!

Dave

[captain_john]

Dave, I am heeding my own advice and beginning canopy work now!

Oh BOY! Here we go!

CJ

[cjensen]

Dave, I am heeding my own advice and beginning canopy work now!

Oh BOY! Here we go!

CJ

Ain't no big deal!!