Mid Fuse Bulkheads - Fuel Tanks - Mid Fuse Ribs

Tons of progress yesterday, and today too! Picked up right where we left off last night and finished riveting the F-1004B Mid Fuse Bulkhead:

The completed F-1004B Bulkhead

F-1004B right side closeup - 30 rivet holes and 8 bolts on this piece, with a vertical line left open for now to accept ribs later on.

F-1004B left side, mirror of right

Two down, two to go! Next up was the F-1005 Bulkhead. This part was pretty straightforward to assemble, the only tricky thing being to take note of all the rivets to be left open for now to accept other parts later on.

F-1005 assembled, with a number of rivets left open per plans

View of left side of F-1005

Lastly, time to assemble the F-1034 Bulkhead. With only 24 rivets, it was done pretty quickly:

F-1034 Bulkhead complete!

Once the four bulkheads were assembled, it was time for "family" photo of the four of them stacked up:

All four bulkheads done!

This was exciting... we completed the first chapter of the fuselage without really breaking much of a sweat! TONS more to do, of course, but this was a great start...

With that, it was time to shift focus temporarily back to the wings, and re-test both tanks for leaks. Both tanks tested perfectly!

L tank holding steady 1 psi

While each tank was on the pressure test bench, I masked off the attachment flange and gave it a quick shot of primer to attach the VA-146 bearing and nutplate shims (from back in Section 18-5 Step 5). This completes the fuel tank section now too... woo! So, why not grab a few screws and bolts and attach them to the wings?

Fuel tanks attached - the wings look huge with everything bolted on!

Wings complete, minus wiring (80% done), bottom skins (40% done), and actuation (50% done)

Exciting! With that, we were able to get just a little jump start on the next chapter of the fuselage, Section 26 - Mid Fuse Ribs & Bottom Skins. This looks like a pretty big chapter, so I doubt it will be done in 3 days like the last one. Either way, here's the first few parts laid out:

The F-1016F-L/R inboard seat rib subassemblies coming together

These subassemblies go along the "tunnel" between the front and backseats, and have parts in them for front seatbelts and rear floor ventilation. Just a little final drilling and deburring, and it was time to call it a night. Awesome weekend of building, hope we can keep this up!!

Flaps - Ailerons - Fuel Tanks

Things are getting pretty hectic in the factory over this long weekend. I feel like we're simultaneously working on 3 or 4 sections at the same time, and all of them are only "half" done. We're halfway through the wing bottom skins but on hold to go any further until we're ready to seal up the wing, we're halfway through with the flaps, we're mostly through the ailerons (except trailing edge), we're mostly done with the tanks but still need to pressure test them... time to move some of these to "complete" status!

Not today, unfortunately. However, we did make leaps and bounds of progress towards this goal. Started this morning with riveting the L and R flap leading edge and top skins to the skeletons. We again installed the flaps onto the wings to check for straightness. They are much more rigid now but can still be influenced one way or the other, albeit only slightly. Still looking straight, which is great news! Then we took them back off the wings and started installing the bottom skins. The flaps are now to the same point as both ailerons: Complete except for trailing edge, and perhaps a few blind rivets that need to wait until the trailing edge is assembled.

With talk of the trailing edges comes talk of Proseal. With talk of Proseal, of course, comes talk of our fuel tanks, namely the goof-up we did with the R tank attach zees being all backwards. So, with the sealant all fully cured it was time to bust out the drill and attempt to carefully remove the seven zees and extract all the rivet tails from the tank. Surprisingly, drilling them out was quite easy (finally, something seemed to go right)! I was also able to fish out about 2/3 of the rivet tails with little issue. The rest of them are still floating around in there for now, but I think the best bet is to try to rinse them out once the tank is sealed up again. We'll keep count, and make sure we get them all.

With the R tank zees removed, cleaned up, and oriented properly, we mixed up a batch of proseal to do the aileron trailing edges and re-attach the zees in the correct order. Happy to say that both efforts seemed to go quite well, and now all that's left to do proseal-wise is the flap trailing edges.

Last thing for the day, it was the "moment of truth" for the L fuel tank. I had bought some fittings, tubing, and valves a week or so ago to make a pressure testing system to connect to my compressed air supply and pressurize the tanks to around ~1psi. This is a higher pressure than what the proposed balloon method allows, which I've read only pressurizes to around 0.5psi. That comes up a little shy of nominal tank pressures during flight when filled with fuel, so I decided to go with this method.

The results were good overall, I'd say. The tank initially held the 1psi pressure, but over the next 10 minutes I noticed it was definitely dropping slightly. A soapwater spray of the tank's exterior quickly revealed the apparent only leak-- at the outboard-top corner where the end baffle meets the aft baffle. Van's points this area out as a common leak source (all four corners, actually), but this particular corner is a sort of "best case" scenario for leaks, as it is the top-most part of the entire tank and theoretically needs to be the least leakproof, so to speak. From the looks of it, we should just be able to goop a bit more proseal on that corner and it should resolve the issue. We'll see if it's that simple... fingers crossed!

Now we wait for some proseal to cure... maybe tomorrow we'll get started on Section 23 - Aileron Actuation! That would be cool, because it's the last chapter of the wing kit! (Except tips, which we're putting off for now...)

Stay tuned!

Ailerons

Finished the ailerons tonight! Well, except for prosealing and riveting the trailing edges, which I think we'll probably do as a batch job with the flaps and the R fuel tank. Oh yeah, the R fuel tank. Guess what I just discovered we did while I was standing here admiring our work on the tanks?

One of these things is not like the other one

While assembling the baffle for the R tank, I laid out all the attach zees in the correct order and orientation to start from the *outboard* side and not the *inboard* side. So the result? They are all backwards (the L tank pictured on the left above is correct). Grrrrrrr. That was an embarrassingly dumb mistake, and I get to take full credit for it. While we were originally putting these together, Sarah had relinquished her responsibility for the orientation of these parts because she didn't want to mess them up, and trusted in me to get it right. That will teach her...

I guess it's not the biggest deal in the world, things could be way worse. Looking through the forums I found more than one case of a builder doing the exact same thing. It's just going to be a time consuming, frustrating, and tedious ordeal to drill out all of the Zee rivets (12 solid rivets along the exterior flanges and 30 blind rivets for the interior), fish out all 30 of the blind rivet ends, regroup, and re-rivet them into place in the correct order. The hardest part is going to be to ensure we recover all 30 rivet ends. I think this is doable as long as we first wait for the proseal to cure, and take our time getting each piece to come out through the fuel fill opening.

Anyway, that was basically the only real excitement tonight, if you can call it that. Otherwise the ailerons are basically done, and we're ready to begin work on the flaps! We've got a number of plans, mostly related to flying over the next couple of days, so we may not get much more work in until the weekend. Oh yeah, and the fuselage kit should arrive at some point this week!

Fuel Tanks - Proseal bottle #7

Finished the tanks tonight! Well... for now anyway. We'll still need to test them and repair any leaks, as well as finish priming and installing the bearings and a few nutplates that we've deferred for now. For all intents and purposes, the tanks are "done".... wooooo!!! That was one of the longer and more painful endeavors so far.

Today after work we mixed up our seventh and final bottle of proseal and installed the baffle for the R tank, in a duplicated effort from yesterday when we did the same thing to the L tank. I have to say it went quite well and didn't take too much time, maybe an hour and a half or so for the entire job, which included about 200 flush rivets on the top and bottom aft flanges and 40 pop rivets to hold the attach zees and baffle to the tank flanges.

With that, it was time to set the tanks aside to let them cure for I'm thinking at least two weeks. That should give us about the perfect amount of time to build the ailerons and flaps, and get them attached to the wings before the fuselage kit arrives. Speaking of which, this is "the week" Van's says the kit will ship, so I can tentatively plan to see the crate here by maybe next week sometime? We're very excited to see it arrive!

Since we got done with the R tank so quickly, we had just a bit of time left to clean up and pull the parts for the ailerons. After some cellophane-peeling and parts-labelling, we had a surprisingly small stack of parts that need to be cut, filed, drilled, deburred, dimpled and riveted together! I snuck in a few minutes in with the bandsaw to separate the A-1005, A-1006, A-1007, and A-1008 bits (pictured below) but other than that didn't do any real "work" on anything. Still plenty more cutting, sanding and filing left to do!

The A-1005 thru A-1008 bits that make up the guts of the ailerons

Aileron skins, spars, stiffeners, and counterbalance

We're hoping that after coming off a big project like the fuel tanks, we should be able to make quick work of these, followed by the flaps which appear to be a fairly similar process, only slightly bigger of course. One thing we'll need to keep in mind is that it is critical to keep these parts straight and square when final-drilling and assembling them... apparently a number of builders have accidentally put a "twist" into them which carries through to the final product. I have read that unless the twist is extreme, it doesn't affect flight characteristics much (it can usually be trimmed out) but it is a definite cosmetic issue. Also, of course I'd rather not build a twisted *anything*. We'll see how well we can do it!

Fuel Tanks - Proseal bottle #6

It was an emotional moment today installing the baffle and closing off the rear of the L fuel tank, effectively entombing all of our hard work on the tanks so far. The last few steps including the vent line, capacitive and float fuel sensors, and wiring seem to have gone excruciatingly slow. The good news is that we're past all that now and ready to close these babies up!

Started today off quadruple-checking all the rivets and sealant bead lines and then blowing out the tank to clear away any dust, metal flakes, etc that might have gotten in there. The proseal from previous rounds has pretty well cured by now, so we had a good read on how it's going so far. It seems to have cured properly and makes a continuous seal that appears to be quite strong and leak-proof... I guess we'll see if that actually ends up being true. One thing that bugged me a little is I found a couple metal shavings stuck in the sealant that I had to wedge out with a fingernail. We've tried like hell to keep shavings out of there but in the end it's just not possible to keep them all away with all the drilling and cutting going on, and a couple must have fallen in. I'm pretty confident they are all gone, but it might be wise to run some extra fuel filtration for the first few hours of operation to make sure everything is out of there.

Last thing was to adjust the L tank float level sensor so that it would have the same Z-bend in it that we ended up with in the R tank. The travel seems much better this way, and the resistance readings are much closer to the desired amounts:

L tank full - 31.7 ohms

L tank empty - 247.1 ohms

After that, it was time to break out our mini-bottle of CS3330-B2 "Access door" sealant to seal up the fuel level sender and the custom fuel tank access panel. I was a bit disappointed that although the unmixed sealant is pink, once it is mixed up it turns almost the same color as regular proseal, with maybe just a dim shade of red.

The access panel (bottom) and fuel level sender (top) sealed and screwed into place.

Then it was time to break out the "real" proseal and final-attach the vent line and fuel tabs to the fuel cap flange. This went pretty well, and we ended up with a configuration like this:

L tank fuel cap flange, tab, and vent

R tank fuel cap flange, tab, and vent

I think the vent is in a near-ideal location and should allow for maximum tank capacity. Although we would have loved to sit and stare at our work, with the proseal clock ticking away it was time to start attaching the rear baffle. We ran a bead of sealant along the top and bottom aft rivet lines on the skins, on the aft rib flanges, and put big globs at each of the four corners as the plans suggested. We also buttered the baffle itself with a thin bead of sealant, and then plopped the piece into place. Using the holes in the skins that had not yet been countersunk, we installed clecoes to secure the baffle into position and got to work installing the pop rivets as well as wet-setting the rivets for the skin-to-baffle seams. It went pretty quickly but seemed kind of messier than usual.

L tank after baffle installation

We pondered doing the right tank, but decided this was enough work for the day. Tomorrow, hopefully we can find time to do the same thing to the R tank!

Wings

Deburred the L wing ribs for bottom skins, and all four bottom skin wing box stiffeners. This EZ-Burr makes things about as simple as possible... still, a thousand holes is a thousand holes, and it still takes some time. It definitely isn't exactly an edge-of-your-seat kind of activity. Good news is, the ribs and stiffeners are all done now, just need to do the skins themselves.

Once that was done, we shifted back to reviewing everything left to do on the tanks. We realized we still had to attach nutplates to the Zee attach brackets. There are a total of 36 nutplates that need to be installed, which is a perfect task to bring into the living room and do while you're watching TV and sipping a tasty beverage. So, that's what we did, and where we left off for the day. Still looking like Saturday will be a good time for baffle installation... stay tuned!!

Fuel Tanks

We're getting so close to being done with the tanks I can smell it! Or maybe that's just the proseal, acetone and MEK. Anyway, whatever it is we're almost done. Tonight we soldered in the connectors for the capacitive fuel sensors and rough-installed the Stewart Warner float fuel senders. Bending the float arms was a little trickier than I imagined it would be, because the floats have to clear both the upper stiffener and the vent line-- there isn't much more space there than the width of the float itself. Additionally, on the R tank, where the float attaches to the rod there is a 'barb' on the rod that could potentially catch on a rivet, sticking the float in the "up" position. This would be bad for obvious reasons, so I was forced to put an extra "Z" bend in the rod on the right side to ensure it would stay clear. The extra bend changes the geometry slightly between the up and down positions, so I may try and replicate that bend so both sides behave the exact same way. For now, here is the position and measured resistances for both floats in the full and empty positions.

R tank empty - 246.4 ohms

R tank full - 30.4 ohms

L tank empty - 256.5 ohms See Update 5/3/2015

L tank full - 56.4 ohms See Update 5/3/2015

Seems ok to me, except the geometry in L tank (without the exta Z-bend) doesn't allow the sensor to swing all the way to the "full" position, resulting in a slightly higher resistance (56.4 ohm) than the desired 30-ohm. The R side with the extra Z-bend came out perfectly, so I'm thinking we'll be adding that same bend to the L side.

Otherwise, once that was done we got out my new favorite tool, the EZ-Burr, and started deburring the wing ribs for the bottom skins. Got all the way through the R wing!

Tomorrow we'll probably deburr the L wing and get everything ready for baffle installation... looking like Saturday will be the last day we see the inside of these tanks!

Fuel Tanks

Tonight we got the tanks pretty near complete before installing the rear baffles. This basically involved painstakingly triple-checking each rivet, and inspecting all the proseal bead lines for consistency and removing any metal chips that might have gotten stuck in there with tweezers. Lastly, it was time to install the capacitive probes I had made. I've chosen to go 100% custom with these, and the plates I've made are similar to (but smaller than) the kit that Van's sells for the RV9 that several others have adapted and converted to work on the RV10. I'll also be designing and building my own controller for these, but that will come at a later time. Basically, installed into each tank is a pair of 1-1/4" wide strip of aluminum sheets positioned vertically near the baffle. One strip attaches to the inboard-most inner rib (#2), and the other attaches to the outboard-most inner rib (#6). They are fastened with three #10-36 nylon screws going into #10 nutplates installed in the ribs, and a few nylon nuts/washers serving as spacers so that the plates are approximately 7/16" away from the ribs. The nylon screws provide electrical isolation from the rest of the tank. On each plate is another #10 nutplate, used to attach a ring terminal and 22-gauge wire to connect the plate to the electrical connector. For the connector, I've chosen a Switchcraft 17280-2PG "Micro-Con-X" available here from Digikey. These are weatherproof/waterproof connectors constructed of nylon, which is not affected by gasoline. After installing the plates and roughing the wires into place, we ended up with this:

The R-inboard capacitive plate installed on its rib

Photo showing the separation of the plate from the rib

The backside of the rib, showing the nutplates with nylon screws coming through

All that's left now is to solder/crimp these connectors into place, and then install the float senders... and we'll be ready to close these babies up for good!

Fuel Tanks

We took a couple days off from building to let the proseal cure and get our next steps in order. In particular, we've been scratching our heads about the fuel tabs, and making a proper mount for the vent line. Both seem like pretty trivial things, but the problem is once the rear baffles are installed, everything is sealed in there "for good" so it's better to take some time now and make sure everything is as it should be.

As for the fuel tabs, I cannot be thankful enough to the folks on VAF, in particular the people who responded to my post about the fuel quantity/height. I didn't have any bites at first, but then all of a sudden we got a number helpful responses, with one guy who actually went out to his hangar and snapped some photos and got me the info I was looking for... Thanks so much to David C (9GT)! There's a Spotted Cow with your name on it at OSH15 if you can make it :-)

Anyway with this new information, I learned that dihedral affects the fuel tanks a bit more than I had estimated it would, and the 20-gallon mark inside the fuel tank is actually 4" up from the bottom, as measured from directly beneath the inboard side of the fuel filler. Since the height of the tank near the baffle is 9", we need to come 5" down from the top skin. Accounting for a 1/8" thick fuel cap flange, that leaves us 4-7/8". So, I got to work fabricating two new tabs of that length.

Similar to the last prototype, these tabs are made from 0.050" 2024-T3 stock and measure 3/4" wide by 1/2", 4-7/8", 3/4" lengths.

The tab mounted inside the tank. With the custom fuel caps, there isn't a ton of room before it would begin to interfere with the baffle, but a slight trim is all it will need to fit just perfectly.

The tab indicates 4" up from the bottom of the tank. The measurements I'm working with came from the inboard side of the fuel flange, as opposed to the outboard side where this is actually mounted, but I can't imagine a lateral inch or two making any noticeable difference.

So that's a huge relief... we now have fuel tabs that ought to indicate pretty darn near 20 gallons! Next was to install a holder for the vent line. This is a perfect example of how deviating from the plans with something even as simple as a different gas cap can lead to further complications that need to be dealt with (The original flange is smaller, and the plans have you just mount it to one of its rivets-- this is not possible with this setup). This is obviously a pretty trivial complication, but even so it takes more time than you'd think just to invent and create a simple mounting bracket, taking all things into consideration. Anyway, after a bit of deliberation, drilling, deburring, and riveting, we had two vent mounts fabbed.

L tank fuel tab and vent holder. Before baffle installation, this piece will be bent to continue following around the fuel cap. This ought to cause it to end at nearly the absolute highest point in the tank, which is the ideal location.

Same setup on the R fuel tank.

Next, we had our first "first" for a while during the build: flaring aluminum tubing. I have some experience bending and flaring brake lines for cars, and I guess I'm ok at it... and this is very similar. But, it's still new to us and the stakes are a bit higher, I suppose. I wanted to document this as well as I could, so here goes (lots of pics):

The Rol-Air 37-degree flaring tool and a bottle of Boelube to be used on the parts while flaring

Tube protruding 5/16" through the top of the clamp, with the flaring die just making contact with the inside of the tube. The instructions say to twist the handle 6 to 7 half-turns from this point to complete the flare. Remember to put the sleeve and nut on the tubing BEFORE creating the flare... last chance!

The end of the tube after flaring.

Once the tube is flared, it fits very snugly over the nipple on the AN832 bulkhead union. Make sure the tube aligns straight with the union to ensure a good seal.

The sleeve is what translates tension force from the nut to the fitting itself once it is all tightened together.

The completed and tightened fitting!

That was pretty much it for tonight, I still need to wire up the capacitive fuel probes I'm building... I've been putting that off long enough! Other than that, I believe we're just about ready to install the rear baffles... exciting times!

Fuel Tanks - Proseal bottle #5

Started off this morning with our fifth bottle of proseal! We installed the T-1005 tank attach brackets and T-1003B aft-inboard ribs on both tanks. This used more sealant than I thought it would, and we actually got pretty close to using the whole bottle on just those four pieces. I used the leftover to install the fuel feed and return fittings, vent fittings, and then drilled out and redid a small handful of rivets we had marked with a sharpie that didn't come out to our liking-- maybe 5 or 6 or so.

L and R tanks, respectively after the last of the ribs had been installed

Close-up of R fuel tank inboard rib. From left to right, you can see the vent fitting, return fitting, and feed flange; as well as custom access panel cutout (bottom) and fuel sender cutout (top)

Close-up of L tank, mirror image of R tank above

Inside of R tank inboard rib

Inside of L tank inboard rib

Once that was done, I got out the coil of vent tubing and realized... doh! We were supposed to install the vent line before riveting the inboard rib into place to facilitate feeding the line through all the ribs. Actually, it wasn't very difficult to feed it through anyway, it just went slower and took a little more care. Next thing to do was get started on a fuel tab. Although it's not in the plans, I figure it would be really useful to have tab sticking down into the fuel tank from the filler neck to mark the 2/3 full point, like you see on some production aircraft. The trick is, how far down from the filler neck is really 2/3 full? Given the angles due to dihedral and angle of incidence the plane sits at on level ground, plus the airfoil shape of the tank itself, this isn't an easy question to answer. I had posted a question on VAF a couple days ago but haven't heard any responses... I suppose it's sort of an odd question and it would take someone to have to go out to their plane and measure. So, I'll have to take a stab in the dark on this. Ready for some Kentucky Windage? Here goes:

Given that the tank is about 9" tall at the baffle, if we were dealing with a square and level tank we'd want our mark to be 3" down from the top. Dihedral causes more fuel to settle near the root than at the filler location, but incidence angle/airfoil shape will affect it also. Best guess, 3.5" down from the filler neck should give us 2/3 full, within say 1/8 tank plus or minus. We'll see how good this guess was in another year or so, I suppose!

The fuel tab, 3/4" wide with lengths of 1/2", 3-1/2", 3/4"

Tomorrow, time permitting, we'll make the second tab and install them to our custom fuel cap flanges, along with the vent line holder!

Fuel Tanks - Proseal bottle #4

Well, we didn't get to do nearly as much work on the plane this last week as we had hoped... I was on travel Mon/Tues, then Wednesday we were both pretty tired and decided to skip a day. Then Thursday our friend Martin offered to give us a ride in his Bonanza to MCW for "Third Thursday" fly-in BBQ and had a blast. It was our first visit to this event, we'll be back next month for sure! Fridays we usually take off from building, and then this morning we went up to IIB for a fly-in pancake breakfast at Walter Aviation. Unfortunately, only Sarah got to actually fly up due to one of the two rental planes our group of 6 was using had a dead battery due to the previous renter leaving the master switch on (aaarrrgh!). Have I mentioned before we can't wait to have access to our own aircraft?!?!? Really frustrating. So we ended up re-shuffling the group and the 4 lightest people still went in the one operational plane. That left me out :-( but I still drove up and re-joined the group for some pancakes and hangar flying. Sadly, shortly before we got there a Cessna 195 had ground looped on landing (~15-20kt direct crosswind) and although the airport remained open, the mood was soured a little bit due to that incident, and we didn't stay and chat as long as we sometimes do.

A sad sight to see, just glad no one was hurt!

No one was hurt thankfully, but it's still a pretty bad day when you wreck a very beautiful and sought-after (not to mention expensive) aircraft.

Anyway.... after we got back home, it was time to shift focus back to the project!

Our friend Alec stopped over again to hang out and witness the "joy" of proseal. We installed the remaining ribs and stiffener into the L tank, which almost perfectly finished off the 3.5oz bottle. So far, four bottles have gotten both tanks to the same stage: ready to install vent line, fittings, and inboard ribs. Hopefully, we'll get to that tomorrow! For now, here's a few pics from Alec, who was on photo duty for the day :-)

Sarah and I posing for a perfect "action" shot building the tanks

Our dogs Dag and Mesa watching the fun

Alec and Sarah being silly... he loves to peel the blue cellophane off the parts, but apparently if he does it too much it gets stuck to his glasses...

Fuel Tanks - Proseal bottle #3

Woke up earlier than normal for a Saturday morning, feeling energized and ready to take on the world. Nothing can ruin that feeling faster than deciding to dive into another round of proseal :-)

In all seriousness, I guess you could say I'm coming around with this stuff. It really isn't THAT bad, it just takes some preparation and organization to keep the mess under control. Also, we're definitely getting into the rhythm of working together on the fuel tanks, and for the most part the assembly process is going quite smoothly. I'm still pretty nervous about leaks though, and that fear hasn't been diminished any by reading all the horror stories on the forums. I think once we finish with all the ribs and are ready to install the baffle, we'll run another fillet around all the seams and any potential leak spots just to keep our 'i's dotted and 't's crossed.

Today, this third bottle of sealant got us through the remaining R tank ribs, as well as two more ribs on the L tank. I think the fourth bottle should finish off the ribs and remaining stiffener for sure.

L tank ribs 2&3 riveted into place

R tank ribs complete!

R tank outboard end rib with fillet

R Outboard tank bay

R tank outboard end rib, from outside

We then spent the rest of the day making a Harbor Freight run for more disposable gloves, had an afternoon family birthday party, and finished off the day with a quick joyride flight to Platteville, WI and back. It was too beautiful of a day to not go up, even just for a bit.

Sort of off-topic, but had to post this here. Last night we went out for a beer with some friends after work, and Sarah's story of drilling through the tank J-stiffener into her finger came up. In order to re-enact how it happened, she improvised a tank skin and J-stiffener using a napkin and a piece of celery. Brilliant use of props!

Sarah demonstrates her technique drilling through a napkin skin and celery stiffener

Tomorrow, maybe more proseal? We'll see....