How can I deal with this Horiz. Stab

[pczar3]

It is interesting that I measured from the front of the firewall to the bulkhead with this twist and it is within a 32nd of an inch compared to the other side. It must be the bulkhead itself that has the slight twist. I'll probably go with the shims and as they say "build on". Thanks again for all the help and suggestions.
Paul

[painless]

Agree with getting your stab clamped in place and aligned to see where you are at. May end up not being an issue. Properly placed shim(s) would be a solution if need be.

Hang in there and stick with it. Us 6A builders/flyers need to stick together!

[JonJay]

Originally Posted by pczar3

It is interesting that I measured from the front of the firewall to the bulkhead with this twist and it is within a 32nd of an inch compared to the other side. It must be the bulkhead itself that has the slight twist. I'll probably go with the shims and as they say "build on". Thanks again for all the help and suggestions.
Paul

The bulkhead may be square flange to flange but it is common in these vintage kits for the web to have a slight buldge or roundness. In other words, the web may not be flat. My guess is that is what is causing the twist.
You might be able to manipulate this into shape by relieving the slot in the deck. I would find what is causing this problem before I just jumped to the conclusion that a shim is your salvation.

[acam37]

I bought a second hand RV-4 kit and one of the rear bulkheads was riveted in the wrong location. I wound up with a 5/16" gap on the vertical stabilizer front spar attach point. Vans said that a 5/16" spacer in that area was perfectly acceptable.

[JonJay]

Originally Posted by acam37

I bought a second hand RV-4 kit and one of the rear bulkheads was riveted in the wrong location. I wound up with a 5/16" gap on the vertical stabilizer front spar attach point. Vans said that a 5/16" spacer in that area was perfectly acceptable.

That is common procedure for VS. However, I have never seen it on a HS. Again, I would want to know why it is the way it is before I contemplated a fix. As it has been mentioned, shimming an out of alignment "twist" is very different than shimming to a parallel or square surface.

[f1rocket]

Van's has the final say in resolving this but I would bet that if you measured from tip to nose on most RV-6s, you would find that the measurements are not the same.

[JonJay]

Originally Posted by f1rocket

Van's has the final say in resolving this but I would bet that if you measured from tip to nose on most RV-6s, you would find that the measurements are not the same.

I wouldn't bet against you!
My main bulkhead is 1/4" off as it came from the factory as a QB. Hence, I have one wing neutral and one with 1/2" sweep. Doesn't affect anything.

Paul, if you can resolve the twist in the bar to allow the HS Spar to be flush to it, all should be good.
At the top of that bulkhead there is a 3/4 x 3/4 x 1/8 angle. The bars rivet to the bulkhead and to that angle. Both bars should be flush to the face of that angle. Perhaps the F-116 Bulkhead assembly isn't flush to that angle on that one side. As mentioned, this could be caused by the web not being flat, but as I look at the plans, that bulkhead web doesn't have much meat at the top where it attaches to the angle. It gets cut out to allow the push rod to pass through.

I would make sure that bar is indeed riveted to the angle and is flush to it. Should be able to see with a mirror.

Call Vans when you figure out what is going on. I am just not a fan of shimming out problems until you know what the cause is. You might discover more things that need attention and the empennage group is one area you just don't mess with.

[sblack]

Originally Posted by acam37

I bought a second hand RV-4 kit and one of the rear bulkheads was riveted in the wrong location. I wound up with a 5/16" gap on the vertical stabilizer front spar attach point. Vans said that a 5/16" spacer in that area was perfectly acceptable.

Only 5/16" ? Lucky Mine was half an inch!

[pczar3]

Well I spent the better part of the weekend measuring and doing more head scratching. When all was said and done, I can see the control stop angle is set at a very slight angle towards the front of the plane. By slight, I mean about a sixteenth of an inch on the starboard side. While standing and looking I noticed the stab mounting bar looked a bit strange. I put a straight edge on that and realized I must have hit it at some point because is was not true. I trued everything up, put the HS on the plane and did the measurements to the middle of the fuselage up front. All it will take is about .020 on the pilot side and everything will be lined up. HS tips are on the button and everything else looks good. I think I'll bolt things up and get ready for the VS mount.
Thanks again to this great group for all the help and encouragement.
Paul