Rudder Issues

I'm replacing the vertical and rudder and it's not fitting.

My plane... Mid-90's slow-build RV-6. I think it's a very old serial number.

Several problems..

I had a heck of a time finding a vertical that even looked like it fit right. There are at least 4 "flavors". I finally found and stuck with the smaller counter-ballanced vertical/rudder. I think is one of the last QB RV-6 vertical/rudders built.

So I put it per the plans with the normal front spar tab and plate and bolted the rear spar to the last bulkhead.

First problem...
The rear spar bends at the fuse bulkhead only a little, but it's bent and the flanges are even buckling a little.

Second problem...
The lower cowl has to be way out as it interferes with the lower attach bolt.

Third (saved the best for last)
The counter ballance interfers and scrapes the top. It needs to be about 1/8" higher, which is a ton.

Here's what i think I need to do *please help*

1 - move the rear spar up higher
2 - Cut the front spar down so it sits lower
3 - Shim between the top of the fuse bulkhead and the rear spar till it's straight.
4 - Open up the counter balance, drill out the rivets where it joins and make a new counter balance section that's higher.

1,2 & 3 should result in a straight rear spar

I'll post pictures in a minute.

Thoughts?!

Hi Bruce,

I built a new rudder for my -4 and getting it to fit the existing (in place) vertical stabilizer was a challenge. I can imagine fitting the pair to an existing fuselage would be even more challenging.

Given the variations between kits (over the years) and builders (skills), I would be inclined to buy a slow-build VS/rudder assembly and take judicious measurements or make fixtures using the fuselage to ensure the proper fit.

Bending spars and buckling flanges seems like a good reason to bail on that parts set.

Good luck,

There's a step in the old Orndorff videos about mounting the rudder skeleton to the VS to establish the proper alignment of the counterbalance rib. Once this is established, a temporary brace is attached via clecos, to the back side of the rudder spar and the tip rib, locking the angle in so that the tip rib can be final drilled to the skin.

Don't know if this'll help in your case. But, it seemed like a crucial step to avoid the problem you're having.

The joint plate that ties the VS front spar to the HS can be mounted on either front or back side of the VS. You can also use a spacer of up to 1/8" on either spar, per my manual. Section 8-20.
You can also fabricate a new joint plate with a different bend location with certain restrictions.
That is a lot of adjustment possibilities.

The counter balance issue doesn't make sense if the VS and Rudder ever flew together.

Thanks everyone, I read them all. I tried 6 different small changes today. Mounting the plate on the opposite side didn't work, but the other 5 did.



Here's my blog post... don't feel like retyping.

Thanks for being my "rubber ducky" everyone. Sometimes you just need to explain it in black and white and maybe it even makes more sense. But more importantly I get "unstuck". Which is the worst.

Glad you resolved it.