SuperFly wrote:Looks good DIck! Missed you at Billys this year! Hope all is okay.
I sure wanted to be at the Fly-In... but an upper respiratory infection has kept me down for a couple of weeks. Never felt terrible, but never had any energy, either. Decided I didn't need to infect anyone else, so I stayed home. Dangit!
Here's one of the tanks in the wing... it isn't bolted onto the brackets, yet, because I need to remove the tanks and clean them out before final installation. It's going to be a wrestling match getting them out and back in to stay, because they're a really tight fit. They're sized to make maximum use of the space available.
Because these tanks are bolted in, we needed a way to check the fasteners during inspections. One option was to cover both the top and bottom of the wing and install eight oblong inspection covers per wing -- four on the top, and four on the bottom. Instead, I decided I'd rather follow the SuperSTOL approach and build tank covers. I'll eliminate the need for access to the bottom by installing 10-32 nutplates on the bottoms of the spar brackets.
The .025" 6061-T6 tank covers will be held on by 6-32 stainless steel screws. Although you can only see them on the root rib, there are 6-32 nutplates all around the tank opening -- in the trailing edge, the ribs, and in an .032" 6061-T6 bracket I epoxied and riveted to the front spar.
The bottom of the tank bay is fabric covered. To hold the fabric off the tank bottom, I epoxied a capstrip across the opening by epoxying short pieces of rib web material at the false rib and at the front spar. When I do the final installation of the tank, I'll apply just a few dabs of caulk on that capstrip to hold it to the bottom of the tank so it doesn't drum in flight.
The tanks are flat-bottomed, so the adjacent ribs are, too. On existing wings, this means adding to the rib structure to flatten the undercamber, or replacing the ribs. I chose to modify the existing ribs, but the modified root ribs aren't very pretty, so I'll cover them with a Kydex insert panel. If I were doing it again, I'd simply replace the ribs.
The new butt ribs are also flat-bottomed, and that provides a bonus: the cover between butt rib and fuselage will be a simple flat part.
Thes wings will remain unfinished for a while... I have the engine in place, and I'm focused on the cowling and the windshield.