Wing root bolt hole slop

[jiott]

Why not just buy the plates and proper rivets from Kitfox? The plates come preformed to the radius of the spar tube. We need to support our manufacturer plus get the right stuff.

[Bluebird19kf]

Because my stuff I have on order is still not here after a month.

[Bluebird19kf]

20180219_112019.jpg So I bought certified 4130 chromoly plate, built a die to bend a blank and made this. I copied the original steel doubler with the exception of making it wider in the rear to accommodate adding 4 more ss rivets. That way I can hopefully try to get the original 4 rivet holes lined up but if they aren't perfect have 4 new ones that will be right on because I will drill them with the plate attached. Do you guys agree with all this or have anything to add?

[jrevens]

I think that looks very good, Brandon. Nice job. Is your 4130 material annealed, or condition N (normalized)?

[Bluebird19kf]

Pic of the blank

20180219_120627.jpg

[Bluebird19kf]

It appears that it is annealed. Is that what I want?
20180219_121643.jpg

[jrevens]

There is a big difference in strength between the “A” and the “N” conditions. You can bring the annealed to a normalized state by heat treating & quenching. I am not sure what Kitfox specifies & uses for these pieces. Condition N is the standard for most 4130 used on aircraft.

[Bluebird19kf]

Called John at kitfox and they are made out of condition "N"

[HighWing]

20180219_112019.jpg Do you guys agree with all this or have anything to add?

This I would add. This was discussed a lot in the old days. Sorry to bring up so much of the "antique" conversations all the time. but during one of the olden day conversations, the stresses put on the wing root during flight was discussed. The wisdom then was that the forces at the wing root of a lift strut suported wing are compressive. In other words the forces during flight would end to drive the wing root in to the fuselage rather than trying to tear it away - even on the forward spar. To illustrate this, one guy posted that once while trailering his Kitfox to the airport - nose forward, the attachment holding the wing back came loose and the air flow over the wing resulted in the wing swinging out into a normal flying position that unfortunately chopped down a sign on the side of the road.

What keeps me flying - when I can still hear, but that is another story - is the fact that about 3000 "Amateur" builders have completed Kitfoxes and there is still to be reported an accident due to a structural failure. I put the Amateur in quotes because there are builders from the perfectionists with tons of time holding tools and the guys who held a screwdriver in his hand for the very first time when he started his build. I think your concern is wise as are your questions, but my opinion is that you have thought it through and your solution is good.

[Bluebird19kf]

Thanks for the replies...I decided just to order the blanks and the rivets from kitfox. I know I wasted time and material but I learned something and that's part of the fun!