RV-7 #74023 - Page 3

longranger · #21 08-03-2012, 11:49 PM

I have a 3-day weekend so I'm going to try to get the left tank done by Sunday. We'll see; Rosie's having a movie night tomorrow, so I'll have knock off a little early.

Today I got all five interior ribs sealed and 100% clecoed. I was slowed down a bit as I had previously neglected to scuff and clean the rib and baffle rivet lines on the upper side of the skin, as well the flanges on the ribs themselves. I mixed one 26-27 gram batch of sealant for each rib, and applied it to both the skin and the rib with an acid brush trimmed to about 1/4 - 3/8 inch long to stiffen it up. This made the application MUCH neater than some jobs I've seen, and also came in handy for forming the fillets.

Yep, I'm the one doing the work:

All five interior ribs sealed and 100% clecoed. Using the trimmed acid brush for sealant application, cleanup was almost unnecessary:

I noticed the skin pullng away slightly from the aft end of the rib flanges, so I dry installed the baffle to pull things into their final positions while the sealant cures. I also clecoed the tank to the wing spar to ensure that the tank didn't get tweaked during assembly. Looks GREAT!

rockwoodrv9 · #22 08-04-2012, 12:05 AM

Looks good Miles. I just got my wings a couple weeks ago. I did a dry setup of the ribs on the spar just to see how it looked. Now the deburring - what fun. Yours is the neatest proseal job I have ever seen. I still have it all over the place from the rudder!

longranger · #23 08-04-2012, 12:39 AM

Quote:

Originally Posted by rockwoodrv9

Looks good Miles. I just got my wings a couple weeks ago. I did a dry setup of the ribs on the spar just to see how it looked. Now the deburring - what fun. Yours is the neatest proseal job I have ever seen. I still have it all over the place from the rudder!

Rocky, it looks like my vacation in Colorado was about a week too early to help you unload your wings.

Beautiful place you have there!

I surprised myself on the neatness of the proseal job today. You can bet the one HRII tank I finished isn't that neat. The proof will be how well it holds gas.

longranger · #24 09-03-2012, 01:17 AM

Definitely a major milestone... at least it feels like it. Today I cleaned out the interior of the left tank, touched up a few spots that looked like they might have a greater than 1% chance of leaking, and ran out of excuses not to close it up.

Sealant beads and smears applied per the manual.

Well-formed bead between baffle and skin. A mirror and flaslight revealed similar beads between the baffle and end ribs.

Cover plate installed with sealant only, no gasket. I used Torx-head screws from McMaster-Carr instead of the supplied phillips screws.

All 21 bracket bolts would start, so alignment is perfect!

The aftermath of RV Tank Building...

longranger · #25 09-17-2012, 12:13 AM

When I first got into the shop this morning, the tank was still on the wing and cool enough from the night before that the balloon I'd sealed to the vent yesterday was sucked in on itself... a good sign - the tank will hold a partial vacuum. After I match drilled the screw holes for the tank to leading edge joint and removed the tank for access to the joint plate and put it on the workbench close to the garage door where the heat of the day could get to it, I noticed the balloon inflated enough to hold its own weight. More good news!

The sealant on the balloon was still sticky and I wanted to give it as much time as I could to cure, so I went ahead and finished the joint plate nutplates, final riveted the W-408 rib, dimpled all the tank screw holes, final drilled the leading edge ribs to the spar, and clecoed the leading edge to the spar (for the last time!) before testing the tank. Toward late afternoon, I pressurized the tank with my in-line pressure regulator set as low as I could and still get flow (about 5 psi). It took a half minute or so to get enough air in the tank, but the balloon finally inflated. No oil canning or bulging that I could detect:

Time for the soapy water test. I got through all the skin and baffle rivets, then turned the tank on end to test the end ribs. Unfortuately, I was so engrossed in the test that without thinking I turned the tank up on the inboard end and popped the balloon (DUH!!). Fortunately, the remnants of the balloon sealed itself over the short tube I'd sealed it to, and the tank still held pressure, so I was able to go ahead and test the end ribs. No bubbles from the infamous aft corners:

Also, as others have reported, no leaks at all on from the Newton deluxe cap. The only leak on the entire tank was some very small bubbles from the schrader valve where it was threaded into the drain fitting. A couple of flats of tightening fixed that. As far as I can tell, this is a leak-free tank, but I may still do the manometer test for an extra warm fuzzy. One down (I hope) and one to go...

longranger · #26 09-23-2012, 11:52 PM

Today, Hal Lyons (on the right in the first photo below) and I riveted the left wing's top main skins using the standard shoot and buck technique, with me shooting and him bucking. Hal has completed and is flying a slow-build RV-7, but had never used a tungsten bucking bar before. Needless to say, he was very impressed, and used it for all but a very few rivets.

We partnered on all of the main spar and rib rivets (next photo), as well as aileron bracket doublers and several others on the rear spar where the shop heads of previously installed #4 rivets might interfere with squeezing. To ease the access to the rear spar rivets we rotated the wing stand to make the aft end of the top skins vertical.

After Hal left I started to squeeze the rest of the rivets in the rear spar, but found that my 2.5" yokes were slightly too shallow, so I ended up shooting and bucking those solo. To make access a bit easier, I rotated the wing stand as shown in the last photo. After finishing the rear spar, I completed the inboard rib with a squeezer, including nutplates for the wing root fairing. To ensure good nesting I gave the nutplate screw holes and the -3 rivet holes not associated with the nutplates an extra squeeze in assembly. The final result looks really good!

David-aviator · #27 09-24-2012, 08:10 AM

Good show, Miles. It sure looks like an airplane wing.

longranger · #28 09-24-2012, 10:40 AM

Quote:

Originally Posted by David-aviator

Good show, Miles. It sure looks like an airplane wing.

Thanks David! It feels good to have another part far enough along to be recognizable.

Now I need to assemble the wing cradle (borrowed from Hal) so I get this wing off the stands and get going on the right one. I'd like to get to the point of sealing the right tank before the weather turns cold (no heat in the garage to speak of). I thnk it's doable, as I prepared the spars and ribs for both wings in parallel.

gib · #29 09-24-2012, 07:51 PM

Looks real good Miles.

longranger · #30 10-29-2012, 10:44 PM

I'm about 90% done with the right (last!) tank. I would have thought I would have learned some way to speed up the process, but it took me just about as long to close this tank as it did the first. I still have to rivet the end rib flanges to the baffle and brackets, install the fuel return and mount the cover plate, and replace a few skin to baffle rivets that are too proud for my liking, but I think I've mixed my last 100+ gram batch of sealant for a while... One anal milestone: I've passed 5000 rivets in the project!

Sealant in place, and ready to close:

4.5 hours later:

Good bead inside right fuel tank baffle to skin joint. I didn't rivet the end ribs to the baffle and attach brackets because it was waaaay to late to run the rivet gun. As a consolation, at least all 21 bracket bolts would start!