RV-7A Forward Bottom Skin Questions

[macrafic]

I'm in the process of disassembling the fuselage to prep the parts (debur, dimple, countersink) for reassembly and rivetiing. I noticed that the 2 lateral forward rivet rows of my forward bottom skin are not drilled to the firewall yet. Some questions.

Did I miss something in the instructions and/or plans? I've checked back and don't see instructions to match drill and dimple/countersink those. Is now the time to do it?

The middle hole on the most forward row is indicated to be left open for the U-720A UPR.AIR OUTLET BRACE. Do I drill this to #12 now or match drill it later with the U-720A? What goes in this hole; a screw or bolt? If a screw, did you guys countersink it or dimple the bottom skin?

For the holes that match up with the floor stiffeners, did you guys dimple or countersink the bottom skin?

I don't have the U-720A. Does it come in the Finish kit or FFW kit?

[cln1owner]

Originally Posted by macrafic

I'm in the process of disassembling the fuselage to prep the parts (debur, dimple, countersink) for reassembly and rivetiing. I noticed that the 2 lateral forward rivet rows of my forward bottom skin are not drilled to the firewall yet. Some questions.

Did I miss something in the instructions and/or plans? I've checked back and don't see instructions to match drill and dimple/countersink those. Is now the time to do it?

FWIW, I'm building a 9, but my directions didn't mention a step for drilling the bottom skin to the firewall. I figured it was OK and time to just do it, and based on Dan's site, I did.

Originally Posted by macrafic

The middle hole on the most forward row is indicated to be left open for the U-720A UPR.AIR OUTLET BRACE. Do I drill this to #12 now or match drill it later with the U-720A? What goes in this hole; a screw or bolt? If a screw, did you guys countersink it or dimple the bottom skin?

Good or bad, others can chime in, I went ahead and drilled the #12 hole.

Originally Posted by macrafic

For the holes that match up with the floor stiffeners, did you guys dimple or countersink the bottom skin?

I dimpled the skin holes for the stiffeners and aft lateral firewall row.

Originally Posted by macrafic

I don't have the U-720A. Does it come in the Finish kit or FFW kit?

Must come in the finish kit, I don't have mine either.

[Flying Scotsman]

I'm at the same step...just disassembled everything to get it prepped for final assembly/riveting

Drilled the side and bottom skins to the firewall and firewall angle/stiffeners once everything was all in place and in final position. I have the finish kit, so we used the engine mount to ensure the firewall was perfectly flat (or at least, that we won't have to use any washers or shims to bolt the motor mount on).

In the middle of countersinking and such now...countersinking all the stiffeners and longerons, dimpling the skins (including bottom skin). Unless it's > .040", I prefer to dimple if possible.

Don't know about that other part...in any case, I'm trying to defer drilling anything to or through the firewall until later, so I can be sure it's in the absolutely best or correct position. Maybe this will bite me later and make something harder to do, dunno...but I just don't like drilling holes for things that aren't there yet unless I have to.