Fuel Tanks/Wings

No proseal today either... but I did take care of a few to-do items that I hadn't gotten around to yet. Attached all the nutplates for the fuel level sensors and tank access plates, as well as fabricated 12 small covers for the 12 small holes in the tank end ribs that the factory uses as guide holes when forming the ribs. The plans call out to do this on page 18-5 step 6. I also trial-fitted my homemade capacitance probes in the tank. They seem to fit well using three nylon screws and washers. I'll make a post about this soon, since it's a whole side-project in itself.

Other than that, did some get-ahead work starting on section 20 for the bottom wing skins. This involved mostly staring at the left wing bays and thinking about where the pitot tube was going to mount. Then I clecoed the gap fairings into place, just in case I wake up in the middle of the night and feel like match-drilling, I guess.

L gap fairing clecoed into place, inboard side

L gap fairing clecoed into place, outboard side

Stay tuned for more tank/bottom skin fun!

Fuel Tanks

Easy day in the garage today. Worked a bit later than usual and didn't really feel like embarking on too extensive of a task. So, I cleaned up a bit and started fabricating some retaining brackets for the fuel return line. The fuel return is going to simply be an AN832-6D bulkhead union that will dump fuel back into the tank. I don't have any pics of the bracket but it's pretty similar to the T-1010 bracket designed to hold the AN832-4D vent union (just bigger, and uglier because I made it by hand instead of Vans' pre-punched deal).

Maybe tomorrow some more pro-sealing? We'll see. I think I'm procrastinating on this a bit, because I hate this stuff, and once you mix it up you're committed to a few hours worth of messy work with essentially no interruptions.

Fuel Tanks - Proseal bottle #1

Happy Easter! Before some evening family plans, we decided to start the proseal adventure! Since we're familiar with it and it seems to work quite well, we're sticking with using the same stuff we used on the empennage, "Chem-Seal" #CS3204 from Aircraft Spruce. It comes in a 3.5oz bottle, and I've got 4 on hand... we'll see how far this amount goes (I'm assuming we'll need more at some point).

We started off with the station looking like this:

Beginning the proseal adventure!

Unfortunately, we don't have any pics of the process itself because, well, we were wearing gloves covered in the most terrible chemical substance known to man. It's not terrible because it's particularly harmful, it's terrible because it's like they designed this stuff to stick to *everything* but yet come off of *nothing*. And it's so goopy. I swear, due to entropy someday the whole earth will be covered in proseal. Sarah still loves it though-- it reminds her of cake icing. She even ran to the kitchen to use an icing scribe to manage this stuff... actually it was a great idea and helped a lot. I'll just need to remind her we need to get a new scribe now and not re-use this one on food. :-)

Anyway, we're now one bottle of proseal down, which got us through all of the R tank stiffeners and about 2/3 of the L tank stiffeners, as well as both fuel cap flanges and the R tank sump flange. We're "wet riveting" which means we're setting the rivets right away instead of waiting for the sealant to partially cure. It's messier this way, but I think it will be easier to have a clean-looking finished product. We were able to exhaust the whole 3.5oz bottle before it hardened, so that was good news too! Here's our completed work:

R tank stiffeners prosealed and riveted

R fuel cap flange

This next week may be tough to find a block of time to do another batch, but we'll see how things go. It's coming together though!

Fuel Tanks/New Toy!

Got the EZ-Burrs in the mail today! WOW these things are awesome. After one day using them, I'm hooked. Out of the box, the blade height has to be adjusted slightly to achieve the desired spring pressure (it's a simple allen screw adjustment). What seemed to work best was setting it so that there is a slight amount of resistance felt by the drill when the blade makes contact with the hole, in both directions. There is definitely a short but necessary learning curve in proper technique, too. You can't just blaze through the hole in both directions-- the blade won't have time to do its job. It takes just the right amount of control and finesse with the drill to have the blade make contact for a few turns of the drill, and then poke through to the other side. Then the same sort of controlled pull on the way back through. After a few dozen holes it became quite simple, averaging maybe 2 seconds (at most) per hole. Speedy!

The 2.5mm EZ-Burr for #40 holes

Using this new device, we made *very* quick work out of deburring the tank skins, ribs, and stiffeners. I dare say, the holes came out better and smoother than our old deburring method, in less than half the time! Did I say I was hooked?

After deburring, I went ahead and masked off all the rivet lines on the inside of the tank for some "targeted scuffing" to help the proseal stick better. This took waaay more time than I thought it would, especially after cruising through the whole deburring process. But, we ended up with some pretty neat patterns in the skins:

Tank skin masked off for scuffing

After a visit with some Scotchbrite

With that, we got right on to dimpling the skins. Most of the holes are #40, although there are six #30 holes that we made for the fuel caps (non-standard) and then a series of #8 screw holes around the perimeter of the skins. All needed to be dimpled (except for a few called out in the plans), so we went three rounds with the three different size dies. It actually went quite well... woo!

Now that the dimpling is complete, it's proseal time!!! Had to clean up the shop a bit in preparation for the process, including lining two of our tables with paper and getting out the gloves, popsicle sticks, MEK, and acetone.

The proseal station!

Tomorrow.... proseal!!!!

Fuel Tanks

Finished final/match drilling both tanks and completed the countersinking portion of the tank skins. No pics, because everything looks pretty much the same as it did earlier. Then we got started on the painful deburring process. Actually, we're putting off deburring most of the holes because we had a good friend and fellow RV-10 builder recommend a new tool I had somehow previously never heard of... something called an EZ-Burr (or competing brand Burr-away). The brand names sure sound promising! Basically, they are smooth pin-shaped bits about the diameter of the hole you're deburring, with a single spring-loaded blade protruding out from the shaft. The blade has a 45-degree edge on both the top and bottom ends. The way it works is, you run the drill down through the hole until the blade makes contact with the edge of the hole, and the bottom end of the blade deburrs the top side of the hole. As you continue into the hole, the blade compresses into the bit and allows the drill to go all the way through the hole to the other side, and then the blade pops back out. Then, with the drill still running, you can pull the bit back through the hole, this time deburring the bottom side of the hole with the top side of the blade. Brilliant!

Stock photo of the EZ-Burr bit I ordered

Between the EZ-Burr brand and the Cogsdill brand Burr-away, I decided on the EZ-Burr because it seemed to get better reviews about the design and ability to change the blades (allen screw vs. micro-size roll pin). Lots of options exist for diameter, blade angle, and rake angle, but I found an older post in the forums from an EZ-Burr rep who stated positive rake and 45/45 angles are ideal for the aluminum sheet we deal with. Also, 3/32" is a little too small for #40, but they also make a 2.5mm (0.0984") model that is best suited for #40. All of this research ended up with me ordering  EZ-Burr models #EZL0098-02 for #40 holes, and #EZL0125-02 for #30 holes, along with a 6-pack of replacement blades that are compatible with both bit sizes. These things were NOT cheap, so hopefully they are the correct ones and work as advertised! If they do, I think they'll be well worth the cost in terms of time saved.

Anyway, other than that we're just slowly chunking away at the fuel tanks. Maybe we'll be ready for Proseal this weekend!

Fuel Tanks

Day 2 of building the fuel tanks... not much more visible progress, just match-drilling, final-drilling, and countersinking. The L tank is ready to come back apart for deburring, and the R tank isn't too far behind. Only noteworthy thing from today is a bit of a funny story. Sarah was match-drilling the T-1009 Tank J-stiffener (Page 18-3 Step 1) on the R tank, as depicted here in the plans:

Excerpt from pg. 18-3

It's a pretty simple step, and one that we've done a number of times before for the wing skins and tailcone... but as they say, the easy steps are where you are most likely to make mistakes. Anyway, Sarah was holding on to the J channel from the inside with her left hand, and match-drilling with her right. I noticed she was in a very similar position to how I did it yesterday, and darn near went through my finger with the drill. So, I cautioned her about making sure her hand was out of the way. The exchange, according to her, went like this:

Mike: 'okay, so just make sure your finger isn't right behind where the drill is gonna come out.'
Sarah: 'okay, okay I got it.'
Sarah: ' owww! Son of a -----!!'
Mike: 'are you serious?!'

She's ok, folks! Barely even drew any blood... quick reflexes I guess :-)

After that, she decided to put on safety glasses. Not sure how those would have helped in this particular situation, but I didn't stand in her way anyway. With that, and after drilling out a few hundred more holes in the tank skins, we called it a night. Should be only a day or two away from our first round of Pro-Seal! (woo...)

Fuel Tanks

Day 1 of building the fuel tanks! We have some mixed emotions about this section-- we're kind of excited for it but also scared to screw them up. It seems most builders struggle at least a little with leaks, and while we accept the challenge we hope we don't have to struggle too much. Also, Proseal sucks, plain and simple. It's smelly, it gets on EVERYTHING, and it's impossible to remove from something once it cures. Sarah loves it for some reason. I'll be sure to put her on Proseal duty :-)

Before we get to the Proseal, we have a lot of prep work to do. Most of this is old hat by now, except for maybe some plumbing which we'll be getting to later this week. We laid out the left and right tank parts on two different tables, and we each got to work on our subassemblies:

The L and R tank assemblies, ready for step 1!

I swear, we actually do real work in this garage. Sometimes.

See?

The first few steps involve fluting the ribs followed by some simple cutting/fabrication of 14 stiffeners, 7 attach "zees", and one J-channel (per tank). After a few hours at the bandsaw and belt sander, we had a pile of parts ready to assemble.

L tank assembly, clecoed together and ready for final drilling

Both tank assemblies

Things went together fairly smoothly so far. Before getting too much further, we had to start on one of the mods we're making. (We are making two modifications to the tanks worth noting: (1) Installing different, larger fuel caps; and (2) Installing a fuel return line.)

A word on the fuel caps: Substituting the standard UD-3 fuel caps that come with the Van's kits is a common practice, however typically folks opt for a set of locking caps that are of a similar size. After receiving the UD-3 caps with our wing kit, it is obvious why people want to use something else... these caps are awful! I can't even fit my finger under the lip to pull the tab up to twist it to get it open! I think uncorking a bottle of wine by hand would be easier... aaargh. To this day, the caps have never been successfully opened, even after a number of attempts from both Sarah and I. They have been put back in the box, and will end up either on ebay or on our blooper shelf (yes, we have a blooper shelf).

Anyway, I digress. We went off the beaten path a bit and chose the ACS-10600 fuel caps for both cosmetic and practical purposes. They twist off like most conventional aircraft, and the opening is a larger, more "normal" size to be able to put a nozzle in AND see the fuel rising as you fill. It's the simple things in life, right? The problem with this method is, the tank skins are already pre-punched for the smaller stock fuel cap, and there are some clearance issues with tank ribs, stiffeners, and rear baffle... all of which are nearby. It took a bit of careful planning and creating a template out of scrap aluminum to trial different mounting configurations, but we eventually ended up with this:

The ACS-10600 cap clecoed into the L tank skin. The cap "sort of" reuses two of the forward-most (at about 5 and 7 o'clock in this picture) holes intended for the original cap. I say "sort of" because the holes had to be elongated slightly to fit the pattern of the new caps. By first drilling them out to #40, we could get everything into position properly, and then by enlarging to #30 the holes are now perfect (We'll use six #4 flush rivets instead of ten #3 rivets to hold the caps in). Three other holes will need to be filled in, as they are not used here (at about 4, 6, and 8 o'clock). It took quite a while to figure out exactly where to mount this cap, and how to enlarge the hole!

View from inside the tank. Some trimming of the cap flange was necessary to clear the outboard rib and rear baffle. It was a lot of work, but I think it's worth it!

Otherwise, aside from some match-drilling, that's about it for today! More titillating tank trials & tribulations... tomorrow!

Wings

Had an awesome time on Thursday hosting the local EAA chapter meeting (www.eaa33.org)! Working on getting some pics from attendees, unfortunately we were both too busy to pull out the camera. It was a great turnout, had lots of great questions and excellent feedback from everyone. The crowd was a diverse mix of the "regular" chapter bums and a few more scarce chapter members, as well as some friends from outside the chapter (and even aviation) that were interested in coming to see the project. Both flight schools in the Cedar Rapids area were represented, as well as some locally renowned pilots and airplane builders-- even three other RV-10 builders (with one completed and flying)! When we get pics we'll post them here on the blog. Thanks to all who attended! It was an honor and a privilege to show you all the fruits of our labor, and it re-energized us both to keep at it!

After the meeting, we took a couple days to settle, re-organize and re-group. Last night I laid out the parts I'd need to finish putting the R leading edge together, and then this morning we were able to deburr, dimple, prime, and assemble the R leading edge. It went together just like the L side, so I didn't take any extra pictures. I did run into a snag with the landing light assembly though. Because of the way I put the cross-supports in, it is too bulky to insert or remove the bracket through the hole in the leading edge. Although I could put it in there before riveting the leading edge on, it would then be "sealed" in there forever, and I'm not a huge fan of that idea. I need to come up with something else. I'm going to bench that project for a while, but I'll need to re-fabricate some kind of mount for the landing lights later. It will be a great rainy day project!

The only other thing we did was assemble the stall warning switch and assembly, which has a surprisingly high number of tiny parts, including 22 washers, 3 little screws, the microswitch/flapper, and the mounting plates. Again, forgot to take a picture, but here's the diagram:

After this was all assembled and installed, we clecoed both leading edges to the wings, and put everything in the wing rack. We'll rivet them on to the spars soon, but we just want to take a few days to make sure we didn't miss anything and have to take them back off for some reason... once they're on, they're on. The wing rack is working out as an excellent storage solution, and everything is really accessible and mobile.

Looking good! Hopefully, tomorrow we will be able to start on the fuel tanks.

Wings

So we decided to invite our local EAA chapter to our house this Thursday for our monthly meeting, and of course that has caused us to needlessly put undue pressure on ourselves to get to a good, clean stopping "show-off" point for the group. I was hoping to have both leading edges done, but at this point it's looking like maybe just one will be ready. No biggie!

Started tonight off priming the L leading edge and riveting the assembly together. It actually went fairly well, I didn't have to drill out a single rivet! (I know, I just jinxed myself for later). Here's the leading edge all put together:

The L (outboard) leading edge, as it will eventually appear on the plane! See the landing light cutout on the end.

Inboard side of the L leading edge, this is where the fuel tank attaches. Still need to attach nutplates (and a fuel tank!)

The rivets came out pretty well!

Underside of the L top skin. Can see stall warning access hatch (inboard) and the landing light cutout (outboard)

Inside of the leading edge, outboard bay

Inside of the leading edge, inboard looking outboard. Note the spar cutouts, getting progressively smaller as you go outboard.

Then in other news, WE FINISHED RIVETING THE TOP SKINS! Wow that took a while. Sarah came out to help rivet the ones on the R main spar (she's on prep duty for the EAA meeting), and then I finished the two rear spars by inserting all fifteen million rivets along each line and holding them in place with rivet tape. Then I just started in the middle of each inboard/outboard skin and worked toward each side, eventually doing the lap joint between the two skins last. The rivets were all pretty easy, except for the six or so inboard-most ones on each wing, where there are two layers of spar doublers coming up to cover the space you'd want for your bucking bar. Using the wedge-shaped bar was critical here, and it had to be held just perfectly or else it would skip out of place and fail the rivet. Had to drill out two or three before I got it right. I think by the time I was done with it all I had the system all figured out though. Funny how that happens.

No more clecos!!!! L top skin riveted, inboard side

L top skin riveted, outboard side

R top skin riveted, inboard side

R top skin riveted, outboard side

The most difficult ones were to the far right (and beyond) on the picture, where the spar doubler comes up to interfere.

L top skin outboard looking inward from the rear spar

I took a few minutes to play quality control with all the rivets, running my hand up and down each row feeling for rivets that were sitting proud. Only found three or four between both wings, and fixed them in short order by either zapping them quickly with the rivet gun and a bucking bar, or drilling them out and replacing. Looking good so far! We managed to only put one ding in one skin, between both wings and surely well over 1,000 rivets, but I'll never tell you where it is... ok fine, it's in the middle of the R wing walk, and it's not even that bad of a ding. That actually works out, because that whole area will eventually be covered with that black non-slip traction stuff. If we had to have a ding, I guess that would be the place to have it!

Of course, now that I had a completed leading edge and a completed wing top skin, I had to attach them together!

L Leading edge clecoed to L wing

L wing with leading edge clecoed into place.

With that, it was time to call it a night. We might do a little more assembly work tomorrow, but most likely we'll just be on cleanup duty for Thursday's meeting. Might not be any more blog posts until the weekend. Until next time!

Wings

Primed all of the leading edge skeleton parts, as well as deburred, dimpled and scuffed the L leading edge skin. Struggled a bit managing the awkward curved skin around the dimpler but eventually got it all dimpled without any dings. Also continued riveting the top skin, finished bucking all rivets that couldn't be gotten with the backrivet set, as well as all the rivets along the main spar on the L wing. Still need to do the main spar on the R wing, as well as both rear spars. Wow this is a lot of rivets!

No pics today since everything still looks pretty much the same. I promise I'll take some pics tomorrow :-)