rudder stops

[jtpitkin06]

I did a search of the archives and found a few references to installing the rudder with the speed kit. I see I’m not the first to have a problem with the rudder stops and the speed kit option.


The instructions direct the builder to file the stops on the fuselage to allow 25 degrees of movement. My rudder moves farther than 25 degrees and it strikes the elevator before the stops make contact. It appears the horizontal stops on the fuselage are about 1/8 inch too short.

Everything is squeezed in as tight as it can be. The rear spar fairing is bonded tightly to the rear spar without any gap. The rod ends are screwed in as far as they can go without the rudder leading edge fairing hitting the rear spar fairing. The rudder leading edge fairing is trimmed and tight against the rudder ribs.

And yet, the stops are still too short.


Others have riveted/bolted and bonded a “U” shaped metal piece to act as a new stop. That's certainly one solution


I’m considering the following:
Drill the rudder stop tabs and install AN3-5A bolts and nuts with the heads on the forward side of the tab. The head of an AN3 bolt would contact the fuselage stop and it would be just the right thickness. It can be filed or shimmed to adjust the throw.

Your comments are appreciated.

Oh… Did I mention how much fun it is installing the rudder bolts through those little slots in the fairing?


John Pitkin
Greenville, TX

[DanB]

Hi John,
I had the same problem with my starboard rudder stop. I ended up using a piece of stainless sheet (about .030) for the "U" and used a couple SS rivets. The only down-side I can think of using the bolt is just a bit more weight.
I think installing rudder bolts in a Kitfox is liken to a sailor crossing the Equator...once you do it, you are initiated ;) Welcome Aboard!

[Dave S]

Hi John,

I think your observation is relatively common. Same issue on my plane during the build (a series 7) - and I did the bond-a-tab-to-the-stop deal like many do.

As a sidebar comment - I figured the specification for the airfoiled tail of 25 degrees vs the non airfoiled tail of 30 degrees was simply a standard specification. The late model kitfox has rudder authority; however, I have never met an airplane that would be hurt by more rudder if it was available - We ended up about 27.5 degrees using a reasonable spacing between the rudder and elevator as the limiting factor and that ended up being about 3/4 of an inch.

I would not recommend diddling with the rudder rudder mount rod ends because a person could loose clearance once the fabric in place. (I thought about that too but scratched the idea)

OK - so it is an experimenal and I did some experimenting - Airplane has behaved flawlessly for 110 hours - no ill effects from the addittional 2.5 degree rudder swing on each side.

Sincerely,

Dave S
KF 7 trigear
912ULS warp

[jtpitkin06]

I think this has the rudder stop problem fixed. It is effective and always in compression, so it is strong.

I drilled two holes in the vertical tabs. Just two AN3-4 bolts and some 960-10 and -10L washers. It's easy to shim the bolt heads to get the proper travel.

[gizmos]

Thanks, that helps