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Required clearance between rudder bottom and tailspring?

N546RV

Well Known Member
This question specifically concerns my RV-8, though I'd expect the answer can be generalized to any model. Today I was working on fitting the fiberglass rudder bottom, and after working through general fitment and installing the thing on the fuselage temporarily, the last thing I was eyeballing was the clearance here.

These photos were taken with the tailwheel on the ground, and the forward fuselage supported by a sawhorse. Minimum clearance between the two is 1/8" about 1.25" from where the spring exits the socket. Further back, clearance is 1/4" at about 2.5" from the socket.

My gut tells me that even under heavy load, there should be much deflection this close to the socket, but my gut is surely biased towards not wanting to muck with more fiberglass trimming. I'd like to collect any real-world experience regarding what clearance people worked towards here, any issues that came up with the spring contacting the bottom in service, etc.

Basically, tell me if I need to suck it up and trim this thing, or if I'm fine.

Photo:
img_2943-768x1024.jpg
 
That looks a lot like the clearance I had on first rudder on my RV-6 that worked well for years (two decades). When rudder was replaced due to cracks, I trimmed the top of the new fiberglass to add more clearance in that area. I also had to cut a section out of the front so that the fiberglass rudder bottom did not rub the rear spar of the vertical stabilizer.
 
Philip,

I trimmed mine for 1/2” clearance. I haven’t flown yet but figured that a 1/2” deflection of the tail stringer that close to the fuselage is doing more than just some damage to the lower rudder cap.

Jeff
 
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