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alpinelakespilot2000

Well Known Member
Anyone else had trouble with the fwd end of their bottom rudder tip interfering with the tailspring? I can't find anything in the archives, but I'm pretty sure I've heard a number of other builders report this problem.

Any suggested solutions? I've already trimmed per the mold lines on the tip, so my options are limited to what that will allow.

Thanks.
 
Seems like I remember the same reports you're talking about. I was advised to leave the fiberglass off the bottom of the rudder until I complete the fuse. Then I can trim it to fit better. I have yet to trim mine at all.

Good luck. Is there no more trimming you can do to lift it a tad higher off the springs?
 
Thanks Robert.

Yes, I could do a little trimming but, because the rudder horn goes into the tip at an angle, any trimming to move the rudder tip up will also move the tip forward or aft relative to the rudder. One solution would be to cut the slot for the rudder horn wider, but then I'll have a larger gap around it when finished. Thus, the solutions are there, I'm just looking for the best one aesthetically.

It's kind of hard to describe without pictures, but when you get there, I'd encourage you to disregard the lines Van's provides for the horn slot and redraw them parallel to the original but fwd or backward as necessary to allow you to move the hole tip up. I only need it to go up about 1/4", so it probably wouldn't have to have been moved much. Hope this helps you.
 
I ended up ordering a new lower fairing when this happened to me. Basically, just ignore the scribe lines and cut a little more at the forward end. It doesn't make a big difference.
 
Yes, Mine did and somehow I did not trail fit the rudder with the bottom on before I painted. So you can imagine I was peeved..:mad:

After thinking on this for a while I fixed it with an easy technique, without redoing the paint or taking the rudder off again.

My interference was only about 1/16 to 1/32 of inch. The rudder would still move over the tailspring L to R but would touch and I could feel resistance as it goes over the bump. I knew eventually it would crack after a lot of landings, or worse do something to the bearing attach points.

My fix was to protect the tailspring with masking tape, Take the weight of the spring, then take sanding paper folded over the tailspring and force it inbetween the spring and rudder bottom and slowly sand the bottom of the rudder away where it iterfeared, by moving the sanding paper wrapped over the tailspring forward and aft. Start with rough and go to smooth. Being fiber glass the bottom rudder fairing sands away quicly. When you need a bit more of a gap so just fold the paper over a couple of times and repeat.

When I was done, you could not see the arching hole on the bottom of the rudder when you stand next to it, difficult to explain but the round bottom curve of the rudder bottom kind of helps to hide the inside curve you sand along the tailspring. Best of all I did not have to take the rudder off or repaint it. I now have clearance and a 'drain hole' as the plans recommend on the bottom rudder :D

Regards
Rudi
 
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Steve,

I did the same thing and then had to re-trim the thing. It turns out this is a common problem.

To solve this problem, I simply trimmed the forward part of the rudder bottom to raise it up some and drilled a new set of holes.



Others have cut and reformed the bottom of the rudder bottom. That seemed like a lot of extra work to me.
 
Here's how I solved it. After going right to Bill's website (but before he posted the above response :D -- thanks Bill!) and noticing that he simply tapered up the fwd portion of the tip, I decided to take sort of a hybrid approach. First, I trimmed as much off the top of the tip as possible, paralleling the original scribe line, and ended up taking off everything above the tail light mold. I then rotated (tapered) the fwd top edge as per Bill's suggestion above. By doing a little of both, I only had to make the rudder horn slot about 1/8" wider than I had it originally, and it's fwd. of the horn so it's pretty hard to see. Ended up working pretty nice, especially since I wasn't really fired up about ordering a second $30 tip from Van's just to move the slot back 1/8"!

At present, I only have about 1/8" of clearance between the bottom of tip and the tailwheel spring right where it comes out of the mount, but there shouldn't be any flex at that point in the spring anyway. If it becomes a problem, I'll follow Rudi's suggestion.

I'll try to post a pick later for those who have no clue what I'm talking about... I think it does affect all tailwheel -7s and -9s though.
 
Steve,

Happy to help.

I'm yet to slap the bottom of the rudder with the tail wheel, even after dropping it in a time or two.

You should be fine.
 
thread bump

So how little clearance is too little?

My tailspring to rudder gap is roughly 1/4". I can't believe the spring could flex that much at that location without doing damage to the bulkhead.
 
Brian,

Up where the spring exits the fuselage you will be fine.

The nut did contact and crack my rudder bottom during my prop strike but it did not make contact by the fuselage.. (The replacement is now held on with #6 screws and plate nuts.)

Other than the torque of the strike drivng my tail down, in 250 hours and a lot of grass fields, the rudder didn't have a scratch.
 
Lower the attachpoint

Hi.

I installed a few hardware items in both end of the chains and on the end of the rudder-cables after seeing the idea here on the forum.
I don't have the partnumbers here, but they are bought from ACS.

They basicilly lower the chain, thus increasing the distance to the rudderbottom, and at the same time prevents damage and ware to the holes in the rudderhorn.
Those chain-clips can enlarge that hole and it'd be a REAL pain to change that part.

Sorry for the not-so-good pic, but at least you'll get an idea.

Maybe someone else can chime in with the ACS part numbers?

 
I trimmed the bottom part of the rudder cap and reglassed to clear the tailwheel spring. I think it is a clean look that does not change the intended angle of the rudder cap. It was not a lot of work. Just cut and glass. The plane has flown on rough grass strips 90% and the tailwheel has never made contact with the cap. Just an idea. Picture attached.

11wa9i1.jpg
 
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