Thorp Air Command - T18.net

Hey everybody. This is Frank Barnett down in the Montgomery, Alabama area. I have been quietly building for a long time now, but I am at the point of mounting my wing and need some advice. Terry Hagle mentioned that most builders are using bolts in place of Ball-Lok pins (can't find these anywhere). Truth be told I like the idea of bolts with locking nuts anyway. So my question is bolt size (specifically grip length).

I measure the exact grip length to be 1.61" (as close as I can see it), but this is without washers. Aircraft Spruce has the AN6-21 (grip is 1 9/16 ; 1.562), but this one seems a bit short. The AN6-22 (grip 1.687) seems to put me more in the ballpark, but washer thickness will impact some with only .077 grip area to play with. AN6-23 (grip 1.812) gives me more washer space.

I need to get my wing attach bolts order so recommendations please. I really don't want to take a chance and order the wrong bolts. This costs time.

Thanks in advance for the help!!!

Well. AC43-13B gives you up to three washers per. There is nothing in the airframe that will get in the way on either side. AN washers are .0625” thick. I’d go with the -23 to give yourself options.
Cubes

Thank you!!

Just to follow up. T-18 or S-18?
Wing center section to fuselage mounting bolts correct? Not outer wing to center wing mounting.

Rob