Elevator Control Horn Mismatch

[skelrad]

I'm getting ready to fit the horizontal stab to the fuselage. One of the things I never did when I built the elevators was fit them to the horizontal stab, so I'm working on that now. Is it normal that the elevator control horns don't actually line up with each other when both counterbalance arms are even with the stabilizer? I don't see any obvious mistakes in the build (it was a couple of years ago, but if I recall, the control horn alignment was set by some pre-punched holes).

It's kind of funny to go back and look at my initial build items. Not exactly pretty! Functional, but I definitely see where the learning curve of riveting was!

 

[bkervaski]

Yes, common. You’ll match drill it.

 

[PaulvS]

There may also be some misalignment of the counterbalance arms, apart from the horns.

In my opinion it is more important for the elevator trailing edges and deflection to be aligned, rather than having the counterbalance arms aligned with the HS. The former affects aerodynamics and control limits whereas the latter is more for aesthetics.

 

[CT Brietigam]

Mismatch RV-14 elevator horn

I came across the same situation. I didn't realize this until after both elevators were built. Instead of dismantling one completed elevator I choose to cut the elevator arm, insert a piece of thin walled 4130 tubing, rosette and butt weld it back together after it was aligned with opposite side horn. I choose to cut the elevator horn that was the most forward to the rear elevator spar since it would limit elevator movement the most. Once the tail fairing is in place, no one is the wiser!!


Chuck Brietigam
RV-6XXL

 

[skelrad]

I just found this note in the plans. Sounds like it's not unusual.

 

[wirejock]

Elevator horns

Yep. More important is that hole be drilled straight. I messed up the first attempt and had to have the hole Tig welded. Second one I used a bushing.

 

[Jim Frisbie]

Cautions

Something to be aware of is that the elevator travel is governed by a point where the horns touch the frame of the tail
With as much miss match as you have you may need to shave the aft. Most horn to get full elevator deflection

 

[skelrad]

Something to be aware of is that the elevator travel is governed by a point where the horns touch the frame of the tail
With as much miss match as you have you may need to shave the aft. Most horn to get full elevator deflection

I took a quick look - looks like the horn that is closest to the stabilizer spar still allows downward deflection within the range called out. It's not the extreme of the range, but about 1 1/2 degrees beyond the lower limit. I'll check it again once everything is mounted and shave a little bit if it's on the edge. Upward deflection is a non-issue.

 

[wcalvert]

" Once the tail fairing is in place, no one is the wiser!! "

Small shudder ..........

 

[PaulvS]

I took a quick look - looks like the horn that is closest to the stabilizer spar still allows downward deflection within the range called out. It's not the extreme of the range, but about 1 1/2 degrees beyond the lower limit. I'll check it again once everything is mounted and shave a little bit if it's on the edge. Upward deflection is a non-issue.

Upward defllection limit is set by the aluminum control stop that is part of the tail cone. A comment above says to shave the horn, this is not correct, the aluminum control stop is filed down instead. Once the HS is bolted to the fuselage and the linkages are installed the limits can all be checked and adjusted as required.

 

[PhatRV]

I had the similar issue with mine. I called Vans tech support and the response was not to worry about it, except to make sure the counterweights are lined up, and to follow the drawing with regard to where to drill the horn in order to have the sufficient edge distance.