Elevator TE alignment

[nzrv8]

Merry Christmas guys,

I'm trying to align my elevators to drill the horns.

With the counterbalance arms clamped to the HS, the trailing edges are misaligned approx 3/8" vertically. The HS is straight, and the elevators aren't twisted beyond 1/8", with straight trailing edges. It looks like most of the error is forward of the hinge line in the counterbalance arms.

Pursuing the forum, it looks like a misalignment is somewhat normal, but I just wanted to see if anyone has recent experience with this level of misalignment, and effects on flight trim etc.

It looks like I could drill as-is with the trailing edges misaligned, or spread the error between both counterbalance arms, with one slightly up and one slight down, pulling the trailing edges closer in line. Or dig deeper and start drilling things apart.

Any insights gratefully received!

H

 

[Taltruda]

Personally, I would align the counter weights and be done.. how are you measuring the TE misalignment? With a straight edge? Once the rudder is on, no one will see the TE misalignment but you..

 

[PaulvS]

My opinion is the opposite and I aligned the trailing edges, reasoning that this is more important aerodynamically and for setting travel limits. If the counterbalances are not aligned with each other it will not be noticeable to anyone.
I used a string line to check the TE alignment.
It is also normal for the horns to not be aligned when the TEs are aligned.

 

[nzrv8]

Personally, I would align the counter weights and be done.. how are you measuring the TE misalignment? With a straight edge? Once the rudder is on, no one will see the TE misalignment but you..

Thanks for your input.. I'm measuring the TE alignment using two straight edges running fore/aft across the HS, then measuring down from the straight edges to each TE.

 

[nzrv8]

My opinion is the opposite and I aligned the trailing edges, reasoning that this is more important aerodynamically and for setting travel limits. If the counterbalances are not aligned with each other it will not be noticeable to anyone.
I used a string line to check the TE alignment.
It is also normal for the horns to not be aligned when the TEs are aligned.

Thanks Paul, good points. I hope to come and check out your project next winter, if you're around? I'll be in Perth for a week or so.

 

[Girraf]

I had a a similar amount of misalignment (1/4-3/8") with my elevators when drilling the horns. I opted to line up the trailing edges of the elevators and split the difference in the error on the horns. I figured a slightly misaligned horns was less likely to influence the flying qualities than slightly misaligned trailing edges.

Take with a grain of salt....my project hasn't flown yet.

 

[PhatRV]

I had the similar issue with the elevator TE slightly misaligned. From the replies here, I think everybody has a small misalignment.

I talked to Vans tech support when this happened and the reply was don't worry about it. Things with the airplane will even out. Just align the counter weight ends and do the best you can. I took it with blind faith.

Now with the plane flying for about 10 hours, everything flies straight, and the elevator force is light. The biggest problem will be the misalignment of the wings if you aren't careful and the aileron TE profile which will cause heavy wings. Mine doesn't have any of these problems so far. Just one data point from a newly flown -8.