Tailcone Fitment issue...

[CMBAero]

Hey all!

So I started riveting my tailcone this week-end... and as I was going... I could see that the side skin on the last two bulkhead wasn't as smooth as all of the other..!? If you slide your hand on the side skin in between those two bulkheads, you can feel a bump now that they are riveted... Is this normal or is there something wrong with my fitment of those two... Before drilling I had played with the flanges to match them to the closest possible with the side skin, but now that they are getting riveted it's a whole new story!

So my real question is, I am alone who is tailcone ends up doing this or is this normal!?

I took some pictures but it's hard to tell with the reflection and such...


Thanks

 

[Hornet2008]

I'm building a 9 and are at the same stage. I'm about to fit the aft bulkhead (F-712) once I have bolted in the tail wheel spring. I have the same problem of ripples in the skin but tried to alleviate it a bit by bending the flanges on the bulkheads out(fwd) and in (aft) on each bulkhead. I've known about this for a couple of months so everytime I see an RV I have a look at the tail cone. Most have ripples.

 

[agirard7a]

thought on this problem

Hello, I am building a 9a. My fuse is assembled. My thought on this problem is that this aft bulkhead is put together with a forward and aft facing flange. I remember hand seaming/bending those flanges (the aft at an acute angle and forward obtuse) this adjustment will better aligned the flange angle with the skin. also, I think if you make the flange angles parallel to the longeron above, you may solve the problem. I am not 100% on this, but worth a try.

 

[OLDSAM]

Me too

My tailcone/rear fuse assembly is now just clecoed together and mostly match drilled, but I recently noticed the same thing. I looked more closely, and saw that the flanges indeed need to be bent more accurately. The front flanges are pretty close to right, but the rear ones need to be bent in considerably more. F-711 needs the most work, but one side of F-712 needs a little attention too. I plan to just take the bulkheads out one at a time, while leaving the rest of the assembly clecoed together, bend appropriately, and re-insert. Will probably have to redrill, and hope the rivets expand a little to fill in what will probably be a less than perfectly round hole.

I had a much worse time with the F-779 bottom tailcone skin not having enough "curl" in it. Got a new one, and it had the same problem. That thick skin is a bear to bend, but brute force combined with finesse (2" steel pipe has about the right radius) finally got it to fit the bulkheads.

 

[PCWebb]

I had the same issue with my 9A and I remember fussing for hours with it to try and get it all to fair in better. Being a boatbuilder, out of fair is not good. In the end, I decided to move on and accept the modest little bump that's there. There is a whole lot of stuff happening in a short amount of space back there so it's no wonder that it all might not be perfect. I've totally forgotten about the issue now that I've been flying 200 hours or so. The flying makes you forget many minor issues.
These planes are awesome (bumps and all!).

 

[CMBAero]

Well I am happy to see that it's a recurrent "problem" with the RV-9/A... Originally, before drilling the fuselage to final size, I had removed them and played around with the flange to get the perfect fit possible...
But now, riveting the whole assembly kinda pulls it back a bit to it's original shape! I guess I will live with this little imperfection, because I think it's as good as it can get without making a mess of drilling the rivets and reshaping the flanges again...

Anyway, for those having this "problem", before final assembly, try to get the best fitment possible by adjusting the flanges...but keep in mind that it is hard to get perfection on this part because like mentioned, there is a lot going on in this little corner!