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 :-)

Wings

Another full day of (non)exciting work on the wing! Spent most of the morning and afternoon deburring, scuffing, and dimpling ALL the leading edge parts for both sides. The plans call for you to only final-drill the spar-to-nose rib holes as it is being installed, but I figured it might be better to do that drilling now before priming and assembly of the leading edge. Plus, we wanted to see what the nose ribs look like when attached to the wing :-)

L nose ribs clecoed to the main spar

R nose ribs clecoed to the main spar

First time we really get to see the airfoil shape of the wing!

We finished the day off by continuing with some top skin riveting. In a burst of motivation and productivity, we got ALL of the rivets that could be back-riveted done for both wings! We also installed the rivets and nutplates on the inboard side of each wing. Now all we have to do is go back over the skins with the conventional flush rivet set and bucking bar and complete the remaining ~200 or so rivets. Exciting times!

Still to-do list for top skins and leading edges:

• Finish bucking top skin rivets that could not be back-riveted.
• Deburr and dimple the leading edge skins
• Prime leading edge parts and skins
• Assemble leading edges
• Install leading edges to wing

Wings

Sarah had to work today and has some family plans later on, so I decided to continue with the leading edges myself, and then I think tomorrow we'll finally get around to continuing/finishing the top skins.

First, the brackets for the landing lights had to be fabricated. An annoying thing about the Duckworks kit that I discovered was that because I got the lampless kit, I didn't get any instructions other than the two templates (skin and rib) and a very rough sketch that shows how it's all supposed to go together. No big deal, but it required figuring out which rivets were for what, and where the nutplates go, etc etc. Also, the baggie that they sent containing all the rivets and fasteners also had a small roll of double-sided tape in it, which stuck to all of the parts inside, resulting in a sticky, goopy ball of rivets and nutplates that was very difficult to separate and clean off.

In order to figure out how to proceed with fabricating the bracket, I relied heavily on Tim Olson's writeup on his site (link here) which helped a ton... thanks Tim! Unfortunately, I don't have any pictures of the fabrication process, but I ended up with a very similar-looking piece to what can be found on his site with the same overall length of 15-1/2" (the distance between the two outboard-most ribs). The only difference is that my cutout in the bracket for the landing light will fit my 40W LED  spotlight instead of Tim's HID setup. I'll take some pics and post them once it's assembled again. It did come out pretty nicely, and I'm excited to see it all installed and working!

Once the bracket was made for the L side, I duplicated the fabrication process to make a mirror image bracket for the R side. Then, I started the prep work on the R leading edge by assembling the ribs, splice strip and J-channel into the skin. Final-drilled all the holes, and cut out the hole in the leading edge for the landing light. Of course, this side does not have a stall warning system, but I am electing to install an access hatch on this side too, just in case we ever need to get in there for some reason.

Unbelievably, there are zero pictures from anything at all today! Sorry about that, it was a lot of heads-down work on the landing lights and then more of the same kind of stuff  that had already been documented for the L wing, replicated on the R side.

Wings

Burned some midnight oil tonight. Instead of doing any more wing top skin work, I continued with the prep-work for the landing lights and stall warning system in the L leading edge. First thing was to cut out the hole for the light. Before receiving the kit, I had searched online for the exact dimensions of the cutout and couldn't find anything, so I snapped a photo of this:

The Duckworks RV-10 template laid over the L leading edge, outboard bay. The light can be installed in any bay, but most people opt for the outboard-most bay for a number of reasons, so I'll follow along.

The hole is 5" wide, 2-1/2" in from the rivet line. It begins about 19-1/8" from the aft edge on top, and 15-7/8" from the aft edge on the bottom. Corners are radiused approximately 1-1/4".

Here's my take on cutting out the hole: I've read a number of build blogs that talked about how scared they were to cut the hole, and then it turned out to be pretty easy. So I guess I went into this thinking no big deal, it will be really easy and take 2 seconds. Well, I guess I struggled with it more than I was thinking I would, because I ended up using a ton of different tools to get it cut out. I used a body saw, an air nibbler, a cut-off wheel, a dremel, a drill-powered sanding drum, and a hand file. No single tool was fit for the entire job, but the combination of them all seemed to do the trick. Finally though, I prevailed, without any dreaded slips or ugly nicks:

The L wing cutout for the landing light

Since I had all the cutting tools out, why not do the stall warning system too? Skipped ahead to Section 20 and began prep work for that.

Access hatch cut into L leading edge skin, inboard-most bay

Stall warning flapper cutout. This works similar to many production aircraft, with a metal tab that sticks out of the leading edge and actuates a micro switch to sound the stall alarm.

Funny sidenote about the stall flapper cutout in the leading edge: RTFI (read the instructions)! The skins come pre-punched with two very small (~3/32") holes to mark where this cutout needs to go. Step 19-2.15 says to file out the area between these holes to make the cutout. However, I missed reading the previous step 19-2.14 where it says to enlarge the holes to #10 first! So, I spent like 30 minutes with the world's smallest file, making a perfect 3/32" slit in the leading edge, thinking "man, this thing is TINY." Had to laugh at myself once it was done and how long I spent making a slit that would have to be enlarged later. Oh well.

The micro switch and components provided in the kit for the stall warning system

Wings

In a burst of motivation, we got all the way through the R wing top skin rivets that could be back-riveted! This excludes rivets along the front and rear spars, as well as the aft 3 rivets on each rib, since the rivet set doesn't sit straight on the rivets. We can either buy a double-offset back-rivet set, or just buck them normally. I think we'll just do that, unless it turns out to not work very well. So far the top skins are coming out pretty darn straight, I'd like to keep it that way if we can! We're bound to ding some part at some time though, I'm sure :-)

"Most" R top skin rivets complete! Sarah is happy :-)

R top skin, inboard looking out

Now we'll have to finish those hard-to-get rivets with a bucking bar and get going on the L wing... the end is in sight!

Wings

We got off to kind of a slow start back-riveting the top skins, starting with the right side this time. Initially, I thought it would be a good idea to insert a bunch of rivets at and hold them in place with rivet tape, similar to how we've back-riveted other parts... but then by an hour or so into this I realized it would be much easier to just cover the bucking bar with packaging tape and insert rivets one at a time as we went (by the way- this is the method Van's calls out in the plans, I was just being ridiculous and trying a different method). Anyway after an hour or so we hadn't made a ton of progress and we were both bored. This is going to take a while to get all 1000 or so rivets done on both wings. We had gotten this far though:

Day 1 of riveting the R top skins

It's a good start, but we have a LONG way still to go!

So with that, we decided to move on to the next part just for a change of pace. Skipped ahead to Section 17 and started the prep work on the L Leading edge:

The L leading edge clecoed together

Some of the ribs had to be notched out to sizes called out in the plans for clearance from the main spar.

It's a pretty basic part actually, consisting of 7 ribs, one J-channel, a splice strip and the skin. I wanted to get a jump start on it though because there are a few modifications required to install the Duckworks landing light kits we got. So, after some final-drilling we called it a night. Lots more riveting to come!

Wings

Excellent progress today catching the R wing up to the L wing! Primed and riveted the R rear spar to the wing. Realized it's way easier to dimple the holes along the top of the spar while it is still off the plane and not assembled, would recommend doing it this way for next time instead of trying to work around all the rivets installed on the spar already. Once the spar was in place then it was time to finish prepping the R wing skins, which didn't take nearly as long as I had thought it would. We're having lots of fun with the new dimpler! The skins were deburred, dimpled and primed within about 2-2.5 hours, which I think is pretty good considering the number of holes. Hung the skins on the wing and now both wings are at the exact same stage: ready for riveting!

Tomorrow should be a "riveting" experience.... (did I already use this joke in the blog before?)

Both rear spars complete! (inboard)

Both rear spars complete! (outboard)

R top skin (inboard) in place

R top skin (outboard) in place

Wings

Today we finished deburring, scuffing and dimpling the L top skins and then primed everything. The L skins are now clecoed into place and ready to rivet! Instead of riveting though, we continued with the R wing to finish the rear spar and top skin preparation. The R rear spar parts (including the new W-1007D) are all drilled, deburred, scuffed, and ready for primer. The R top skins have all been final-drilled, countersunk, and nutplate attach (inboard side) all prepped. Still need to finish deburring the holes, then scuff, dimple and prime. Once that is complete (hopefully tomorrow) we will be ready to rivet both L and R top skins to the wings!

L outboard top skin after dimpling, ready for primer!

Priming the skins with Rustoleum aluminum primer

The R rear spar parts all drilled, countersunk, deburred, dimpled, and scuffed... ready for primer!

The L top skins in place and ready for riveting

L top skins from the other side

Wings

Started off this morning not working on the plane directly, but wanted to make some improvements to my dimpling tool. When we started this project, I decided I wanted to make my own C-frame dimpler embedded into the work table. I've seen the commercially available ones, and of course the DRDT-2, but for me I couldn't justify the cost if it didn't do 'exactly' what I wanted. So... I got to work on an idea I had a while back to make the best dimpling device ever. If I failed, I told myself I'd just break down and get a DRDT. To my own surprise, I think I succeeded! Total cost? $0.00! An aviation first! :-)

The idea was to attach an air hammer (or rivet gun) to a swinging arm that could go up and down towards the very edge of the workbench. On the gun would be the male half of a dimple die, and then the other half of the die would be placed into a very heavy steel block, slightly recessed into the work table at the very edge. This way, the dimpler can accommodate very large sheets (i.e. wing skins) and process them very quickly and consistently, since the air hammer will always be held straight and level by the swinging arm. Also, since the lower block is embedded into the edge of the table, it will be perfect for dimpling the leading edge curves using the gun and dimple die by hand.

The dimpler was built using some leftover 1" x 1" square steel stock from the first dimpler, some angle iron, steel plate, hose clamps, and an old air hammer that I've had for a while and still works great. It felt very MacGyver-ish, only I didn't need to use a paper clip or duct tape. The air hammer isn't as "precise" to control as the rivet gun, i.e. there aren't numbers printed on the air control valve but otherwise I still can't tell the difference between the two for the life of me, other than the price (Maybe that's what the "3x" means? ;-)). Anyway the air hammer is perfect for this. I test-ran it on some scrap running the gun at 35-40psi with a 1-second or so burst and the dimples came out 100% perfectly coined! I think if someone wanted to go out and buy all the parts new for this they'd spend less than $50. Here's the completed setup:

Some steel stock, angle iron, and hose clamps and a couple bolts attach the gun to the swinging arm.

The gun, arm, and attachment to the table. It does have some side-side slop, but as long as you don't really torque on it, it is quite easy to line up with the die. You can also see the patch job I did to cover the previous hole where the old C-frame dimpler was set up. Not the prettiest, but it works.

Straight and level from all angles. I put black carpet over the lower block because it was an ugly mess of steel bars and cut-up 2x4's, this makes it look a lot better.

When you're not using the dimpler, you can swing it up and out of the way. I should probably put some sort of up-lock on it so that it doesnt get bumped and come crashing down. Maybe a spring too. We'll do that in v2.0.

Anyway, on to the actual work for the skins. We final-drilled all the holes in the top skins, and I also countersunk/dimpled the areas of the top skin that needed to be while still on the wing. No pics, since it pretty much looks the same as it did yesterday. Towards the very end of the day, I was able to pull the L top skins back off the wing for the exciting task of deburring/dimpling. I got through the wing walk doublers and the inner skin (the smaller of the two), and decided to call it a night. Good news though, the dimpler works perfectly!

The MikeyJ-2000 dimpler in action on the W-1002 top wing skin!

Dimpled, scuffed, and ready for priming!

And that's all for this weekend, folks! Hopefully this week we'll get through the top skins on both sides and be ready to tackle the leading edge!