Rudder Stops Alignment and Clearance

[JeffKinMT]

I've been working on the rudder fairings on my SS7. The rudder stops on my kit were welded to the main fuselage structure in a misaligned position, to the extent that the left side was making contact with the inside of the rudder front faring. To get it to clear, I had to grind a slot in the fairing, so now the rudder stop extends outside the fairing.

Once I got to this point, I took a pause because I realized that this just cannot be right.

So, I see some fiberglass work in my future to close up the slot, but then I'll be grinding down the outer edge of the stop to get the necessary clearance--about half of the width of the stop. I wonder if the stop will still be stiff enough after removing that much material.

Does anyone have a bit of guidance for me on how to address this problem?

RudderOff.jpgRudderOn.jpg

[Meyer]

My .02 is I would not touch those until after covering is done. I did not grind mine at all pre-covering. After it was covered, my original alignment needed to be moved out. The fabric was thick enough that the rudder needed to be spaced aft, if that makes sense. Then I checked clearance with the elevator. One side was fine, on the other I needed to put a stop on the inside. No grinding on that horn, actually had to drill/tap and put a bolt in to extend the stop inside. If I had ground that down originally, would have been worse.

[JeffKinMT]

I’ve read that advice in several posts here, and do plan to do that.

But in this case I’m not needing to grind the stops to adjust the rudder throw. Instead, I need to grind the left one narrower, so it doesn’t protrude out of the left side of the rudder’s leading edge fairing. It looks like I’ll need to narrow it by at least half, which raises concerns re: stiffness and whether it will still line up with the tabs on the rudder itself.

I guess another option would be to cut the entire piece off and re-weld it on straight, but I have never welded a thing, and this seems like a poor choice for a first project!

I guess this post is just to see if there’s an “easy” solution that I’m not able to see.

[JayHenry]

Send the pictures to Brandon at KF he always has the best fix and he is awesome about responding to your questions.
brandon@kitfoxaircraft.com

[Jerrytex]

Mine was exactly the same way but I believe on mine, it was the right side. I ground and shaped so it fit in the confines of the fairing. I did not grind for the stop length yet. That will be adjusted after covering. I also had to tweak my lower rudder bushing to center the rudder in line with the upper bushings. What I found was at full deflection, the leading edge of the rudder stuck out further, past the fairing, more so than the other side. It was a miniscual amount of tweeking, but it made a huge difference and lined up everything nicely. I would check and adjust that first, and then shape the rudder stop bracket.

I have found a couple of places on my 1994 fuselage where the welder was like.....ehh....it's close enough. But then again I just installed my new fuel tanks and experienced similar workmanship. One tank plopped right in....perfect fit. The other side was a nightmare. It teeter totted 1/4" diagonally like it was built warped. I had to grind and fit for hours and it's still not 100 % right. Frustrating to say the least.

[Maverick]

the first owner of my kit had a little misalignment and proceeded to grind and cut to the point that the rudder would hit the horizontal stabilizer. I welded these on to restructure the stops to a usable length. I did have to grind the heads of the bolts off a small amount to get the rudder deflection that I wanted but, it is working fine.

[efwd]

For those who don't know how to weld and or have no welder there is an alternative. On the rudder half, you will find the upturned metal that is what mates with the stops on the airframe. I drilled and tapped a hole, through which I placed a bolt. I have a jam nut on the bolt and when the bolt was at proper distance I locked it down with the jam nut and used a second nut on that to maintain the placement. My bolt head then contacts the stop.

[JeffKinMT]

Quoting:

I also had to tweak my lower rudder bushing to center the rudder in line with the upper bushings. What I found was at full deflection, the leading edge of the rudder stuck out further, past the fairing, more so than the other side. It was a miniscual amount of tweeking, but it made a huge difference and lined up everything nicely. I would check and adjust that first, and then shape the rudder stop bracket.

Jerry, can you provide a little more detail on the tweaking you did to the rudder bushings? (Maybe we have different attachments; mine are threaded rods with ball ends.) While I have the same issue with the rudder's leading edge being a little right of center, I don't see how I could adjust the alignment of the rudder attachment hardware to change that...?

[Jerrytex]

So what I found was if I ran a rod through all the rod ends (eye connectors) they were not all lined up. The bottom one was slightly off center. (I can't rememer which way) This caused the bottom of the rudder to be slightly off center but still within the confines of the front fairing and hard to really notice. But when deflected, the fact that the lead edge of the rudder fairing is forward of the pivot point (where the rod end and rudder mount tabs go together) it seems like it magnifies the slight off "centerness" (if that's a word) of the lower bushing. This caused the lead edge of rudder fairing to stick out in the airstream more on one side. So what worked for me was..... I used a piece of tubing that fit over the lower bushing nice and tight. I carefully "Tweaked" or bent the bushing slightly. Like .25-.50 of a degree. When you put the rod end back in, the movement is amplified and even more so when the rudder is on. I think what happens /happened, is when welded, the bushing moves slightly by heat distortion. Or its possible that the bushing was bumped or banged. Either way, this worked for me. I also remember when I re-shaped the rudder stop plate, I rounded the ends of both "horns" to fit in the fairing. My rudder stop plate looked just like yours only a mirror image. I kind of wonder if they got some slightly crooked rudder stop plates and depending on which side they put up before welding, changed which side the problem ended up on.

rudder stop.jpg

[JeffKinMT]

So this is what my rudder stop looks now that I've finished grinding down the left side so it will fit inside the rudder fairing. It's still quite stiff and I think it will be perfectly functional.

After.jpg

Jerry, I also have the same issue you mentioned re: the bushing alignment. When I mount the rudder, it's offset to the right relative to the vertical stabilizer toward the bottom. The gap between the vertical stab and rudder fairings is even at the top, but becomes much wider on the left side as one moves down to the bottom of the rudder. Strangely, the ball ends all line up, so I'll have to adjust the middle bushing a bit, and the lower one a bit more to get everything aligned properly.

Thanks for the info, everyone!

Jeff