Section 20 - Bottom Wing Skins (riveted inboard lower skin); Section 21 - Flaps (prepped skins; drilled wedge, nose ribs, hinge brackets); Section 23 - Aileron Actuation (finished torque tube and pushrods)

Good progress this week, especially considering I spent much of it slowly riveting the inboard lower skin to the wing (and did that entire skin without assistance from a bucking partner). I bought a new 1.5lb tungsten bar that fits in tight spaces far better than my larger tungsten bar, which aided the process considerably.  Of course, there was a learning curve - for example, if the bucking bar doesn't feel right, don't just pull the trigger (i.e., I made a couple slight dings). Likewise, I started this process with the gun air pressure way too high, and soon dialed it back down after a few rivets. Overall, the lower skins are a real pain in the ass - you work for every rivet by stretching, figuring out how to bend the skin some (but not too much) in order to reach ... not a fun process, but a decent learning experience.  The rest of the week included finishing the left torque tube, the left bellcrank-to-aileron pushrod, and making good progress on the left flap. Details follow:

Riveted the threaded rod end to the internally primed steel tube by sloooowly squeezing the -11 (!) rivets with the Cleaveland Tool Main Squeeze manual squeezer.  These long rivets wanted to lean over, so I had to adjust the angle several times:

Rod end bearing and jam nut installation on the bellcrank-to-aileron pushrod (jam nuts NOT final-torqued yet):

Primed parts for left torque tube (only inside the white powder-coated tubes; inside and out for the collar):

Drillled forward tube to collar, bolted, and then drilled the aft torque tube.  Note that the aft tube has a very specific clocking specified in the manual, which involves fabricating a 1 1/32" block upon which to clamp the bolted flange:

Torque tube, final drilled, and ready for installation on left wing:

Finished left wing access panels for lower skins:

Started riveting left lower inboard skin:

My three tungsten bars - the one on the lower left is what I used (after covering most surfaces with duct tape) for riveting the lower skin:

More riveting left lower inboard skin:

Aaaad, more riveting left lower inboard skin ... oh wait, I think I'm done here:

Attached nutplates for the inboard-most access panel:

Riveted inboard-most rib and nutplates to lower skin:

Placed left outboard lower skin on wing assembly and clecoed the first area (around the outboard flap bracket) to be riveted.  I'll need help with this skin:

Clecoed top, bottom and nose skins to left flap assembly:

Other side, after match-drilling nose ribs and final-drilling trailing edge:

Match-drilled flap hinge brackets: