PA-12 restoration started

Another option instead of the x brace is to do the "U" brace that goes in the same spot and carries all the way up to the top longeron, and has another horizontal tube set further back to clear the elevator cable. Also while its apart check the horizontal attach fitting at the longeron very well, they can crack at the front side in the longeron.

Both of my PA-12 airframes had a box reinforcement, similar to the Atlee clamp-in box, but welded in.

The x brace won't interfere with the stringers if a stock appearance is important to you.

Here is the Atlee Dodge version: Either this or the X works fine.

Could someone please post the distance from the tailpost to the fuselage cross brace? Does it coincide with one of the horizontal crossmembers?

The most effective location for the X brace in the tail section will be half way along the unsupported longeron and half way on the diagonal. The box in this pic should probably coincide with the cross tube in my opinion.

Just for reference, one time a friend had recently added 31" Bush wheels to his new to him Super Cub, he wanted
me to fly it and give him an honest idea how it compared to lots of other Cubs I had flown. So I jumped in it and ran up to hunting camp and threw in a front shoulder and hind quarter of a big Moose, then the headskin on top of the meat. Back taxied on a 600' tundra strip and swung the tail out around in the virgin tundra ( where we always turned) unbeknown to me the tail was NOT boxed in......(or X braced )
When I landed back at lodge, he rushed out to greet me and get the appraisal on how she compared. Then we both noticed the fabric was sagging badly on one side of fuselage!!!!! ONE turn in " rough stuff" can tweak your fuselage. So if you don't think this is one hell of a critical mod: better think again.
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flybynite said:

The most effective location for the X brace in the tail section will be half way along the unsupported longeron and half way on the diagonal. The box in this pic should probably coincide with the cross tube in my opinion.

View attachment 65133

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Thanks! Just what I needed!

Not shown in that pic is the longeron support from the jackscrew tower cluster area, my U brace is 16 3/4 from tailpost OC on bottom longeron, tilted back. Horizontal piece (not required in an X brace), is 13 3/8 from tailpost OC. With an x brace you dont need to worry about elevator cables hitting it as much but if you do go half way up the bay I would double check.

I should have added that the tail section shown has been replaced with a Univair short section that included an X brace. I couldn't find a pic of it that illustrated the location as well as this one did.

Can someone verify the wall thickness of the lower longerons on a PA-12? .035? I am going to replace about 10' on each side of the rear tubing.

3/4" x .035" is what Piper used.

Steve Pierce said:

3/4" x .035" is what Piper used.

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Thank You!