Still dragging my way through the wings

Spent most of the long weekend working on a project for my brother… He wanted to make some replica B-17 nose art.  So I fabricated a 26″x26″ fuselage section.  It’s curved with two ribs and two stiffener and some AN470-4 rivets.  It came out pretty nice — it just took a bit longer to build than I hoped.

Then I got back to work on the aileron control rods.  I primed the main rods and started to assemble.  I was short some of the cherry max rivets, so I had to defer further work (and get an order out to Aircraft Spruce so I can have them by next weekend!).  One of the mandrels got stuck in my puller, so I had to break out my father-in-law’s trusty puller that worked like a champ.

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So I started working on the gap seals.  The blue plastic was really clinging to the aluminum.  This does not bode well for when I pull all the old stuff off.  I had to strip off the adhesive with a large dose of acetone.  The worse news was that when I went to go dimple the seals, I found that my trusty Main Squeeze’ cam had broken.  It just doesn’t reliably go up and down.  So that meant that I had to bang out another order to Cleveland Tools since I don’t see a way to make much further progress without a good hand squeezer.  I did make some progress  by dusting off my pnuematic squeezer, but while it was fine for dimpling, I found that was having problems actually squeezing rivets (it may be because my air compressor seems to max out at 90 lbs pressure these days).  Sigh.  At least the new tools and replacement rivets should arrive before the weekend.

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I had to do some work to actually fit the seals onto the wing.  The new aileron attach brackets are a bit larger and beefier, so I had to trim one end and make sure there is no interference (and no stress corners).

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So, next week I’ll hopefully have the gap seals on and the aileron rods in place.  I made sure that I will have all the AN hardware (I ordered some extra from Aircraft Spruce to make sure).

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Lots of little things to finish on the wings

I’m still working on the wings.  There are a lot of little steps that I skipped past when I did this kit out of order.  Now that I have the wings mostly in one piece, I’m catching up and getting to them.

The wings are in a wing stand now.  I built a new one because I wasn’t happy with the old one and didn’t want to use the “sling” style to hold the wing up.  I just assembled the wings flat on my tables.

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When done, I tipped them into a lower stand made out of 3×4 plywood ends.  My son stopped by the hangar after his flying lesson and helped cut them out.  I just used a rib end and the leading edge tipped on its side to get the outlines.

Then I just added some 2×4’s to hold it all together with some castering wheels from the old stand and voila!

With the wings together and accessible, it was time to clear some of the backlog…  The wiring harnesses look deceptively simple to install.  They do pretty much just thread through the ribs in the grommets I installed oh so long ago, but you also have to correctly isolate and install a couple dozen wires into Molex connectors.  So, it involved lots of staring at the wiring diagrams and tugging wires to make sure I had the right white wire for pin 12!  Eventually, I got everything in the right place and did some initial zip tie work.

Another thing that was left hanging was addressing SB 16-03-28 which covered a potential for cracks in the spar at the aileron attach bracket.  This is one of those “inspect and fix if found” annoyances, but I wanted to be in front of it (in part because it is hard to inspect and a royal pain to fix if found.  With the bottom skins off, however, it is relatively easy to accomplish because I had access to both sides of the spar for drill out and for squeeing new rivets.

First up, I removed the old brackets and recovered the bearing (it gets reused in the new bracket).  The old bracket had a thick aluminum piece sandwiched between two thin bent pieces.  The new bracket has two thick pieces and super thick angle irons and a doubler plate and a secondary brace.  Even just clecoed in place, it is much stiffer with no discernible flexing.

Of course you have to go through the whole, cut out the pieces, file, deburr, etc… shenanigans.

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It was a bit tougher to squeeze the rivets than I thought it would be.  The clearance was really tight.  For the first one, I built the full bracket and then tried to rivet to the spar.  This didn’t work well because the bracket rivets interfered with the spar rivets.  I smiley’d three rivets with the squeezer and the offset rivet set before I got wise and ground down the squeezer yoke.  This got me 7 of the 8 rivets.  I had just purchased a 5.5″ yoke that I was able to use to get the last one.

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I still need to put the skirts on here and those will need a minor trim job to fit around the larger brackets.

Finally, I got to work on the aileron control rods!  It took a long time to dig out all the parts.  The wing kit parts had become a bit scattered over the last two years.  Plus I have already unpacked the fuselage kit which adds to the clutter.  I finally dug out all the rod ends and found the 1 1/8″ and 1/2″ tubes and the torque tube collar piece.

I cut the rods to length using a chop saw with a metal cutting blade.  The 1 1/8″ tube is thin walled aluminum and cut easily.  The 1/2″ powder coat tube, however is steel, so cutting it gave me a spectacular shower of sparks.  With the cuts made, it was time to pilot drill the 6 holes on each end.  I used a cheapo Harbor Freight V-block in my drill press.  It worked great.  It would  have been difficult to control without the block.  Once the pilot holes were done (and roughly deburred), I slid the rod end pieces in to match drill them the same way.

With that behind me, it was time to final drill to #30 and swap the silver clecos for brass ones.

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The tubes and rod ends are raw aluminum alloy and need to be primed — inside and out.   Another builder I saw online was clever and taped off the end of the tube and poured in primer and then inverted the tube to let it drain out.  I did this, though I had a catastrophic containment failure when the tube end tore my glove and lacquer poured all over my hand.  I also primed the rod ends (after carefully labeling them so I could get them back into the right tube).

Next week is a long weekend, so I should have some time to finish out the aileron actuators.  I should also be able to get the gap fairings installed.  At that point, I really only have to finish the bottom skins for the wings.  I’m going to defer that until I really have to.  It’s nice having good access.  Plus, once I cleco the skins on, I’ll have them out of the way so I have enough room to start work on the fuselage.

Wings finally coming together

It’s taken a while, but the wings are finally coming together.  With both tanks finally finished (there was a trivially easy to fix leak in the second tank in the corner where the tank attach bracket met the inboard rib… I just syringed some proseal into the gap and it closed up nicely), it was time to move on with getting the wings together.   I had a couple of projects on the leading edges that I had to finish.   While still in NY, I waited to finish the landing light covers because I didn’t want to finish them in the sub-zero temps.  Well, here in Houston, it was a balmy 94 degrees.  No more excuses.  The fit is OK, but I feel that I could have gotten a better seal.

 

I was thinking about building over the 4th of July holiday, but instead spent a nice day down at the Lone Star Flight Museum.   They had the B-17 open for tours.

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With the lenses in place, I fitted the stall warning switch.  I debated leaving this off since I’m planning to install a Dynon heated pitot with angle-of-attach sensing.  However, it is such a simple device that will help more than hurt, so I left it in.  I can always disable it or remove it if I find it burdensome.

With that, it was suddenly time to start assembling the wings.  The leading edges are permanently installed (rivets for the ribs, driven rivets for the skins).  I started with the LP 4-4 and LP 4-5 rivets that hold the inner ribs in place.  It is a tight squeeze, but it is so much easier to do this without any proseal clogging things up.  I used my father-in-law’s pop rivet gun here because it has a very narrow head which let me get in right next to the ribs.

Then I started to get the fuel tank in place.  Here, I only have a few bolts holding it in place, but it really looks like a wing now!

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Next week, I’ll finish the left wing (bolts and screws for the tanks and the rivets that I can reach for the leading edges) and get started on the right.  I’m building a new wing cradle that can better hold the wings at this stage and prepare for riveting the bottom skins and applying the spar strengthening service bulletin.  I’ll leave the bottom skins off until closer to wing attach point.  It is much easier to initially fit the aileron controls, for instance, with the skins off.  Same with getting servos and pitot masts and and other things fitted.  It will move up the day to start on the fuselage as well!

After a long hiatus… tanks — a lot!

I’ve haven’t blogged anything in almost 9 months, but I’ve been very busy.  I spent a lot of time working on the my RV-12.  The condition inspection (more specifically, my updating the radio and adding ADS-B In/Out (a new GPS antenna and a new ADSB-In antenna) really kicked my butt.  It dragged on and on.

But through it all, I kept grinding away at the tanks.  It was really slow going.  Mostly I think that this was mostly mental.  I knew that I would have to break out the ProSeal and I kept prevaricating and didn’t get to the end.    Well, finally, I just decided it was time to dive in, so I did.  There aren’t a lot of pictures because my hands tended to be covered in grey, icky goo most of the time.  These pictures will cover many months work.

 

The fuel and drain fittings went in much more smoothly the second time through.  I was finally getting the hang of working with the sealant and got my riveting groove back after being out of practice for so long.  I got a nice squeeze out and made sure to thoroughly cover all the possible places it might leak.

For some reason, I was really looking forward to getting the fuel caps installed.  Maybe it’s just the nice contrast between the anodized red filler and the (not so) shiny aluminum.

Next, there is a lot of back riveting to do.  I tried masking off the areas around the stiffeners, but found that (1) it didn’t really help keep things clean and (2) it made it hard to form a nice bead of sealant.

I took the leading edge stands and built a little rotating adapter that I strapped to a low bench.  This proved very handy for getting a good angle for the riveting work.  This put the wings at a comfortable height and allowed me good access to both sides.

Another thing that proved handy was having small plywood backing boards.  These fit inside the ribs and made them straight and stiff for inserting whilst covered in sealant.  Also, if I needed to, I could give them a gentle tap with a dead blow hammer to get them to sink into place.  I highly recommend making a pair.  They just flip over to do the other tank.  One is long (for tapping) and the other sits inside the flange to give some strength when bolted together.

I also cut another piece of plywood cut slightly bigger than a rib.  This was useful for gently spreading the skins apart when I was sliding the ribs in.  It helped get the skin into the right shape and made just enough room to slide the next goopy rib into place.

 

The riveting was very messy.  I got everything together though and obsesses over covering each rivet head.  The J-stiffener was pretty hard to get in with enough sealant.  The instructions suggest that you can slide it in without touching the skin, but I found that I dragged off some of the sealant anyway.  I added a little more on the insertion side and it seemed to achieve good squeeze out.

 

I needed to fabricate the vent line.  One open end sits at the highest corner of the fuel tank (near the filler cap).  It comes back to a fitting on the inside rib (where the flare fitting is).  It was my first flare (I used my father-in-law’s flaring tool, so I didn’t have to buy one).   It came out very nice with no cracks.

 

In April, I was headed out to a conference near Portland, so I had to stop in at the mother ship.  It was a Friday, so the factory floor was empty, but I still got a nice tour and got to sit in the original 14A!  It was much roomier than I expected (and a bit taller).  It certainly reinvigorated my desire to get working again.

When I got back, I finally got around to fabricating the fuel floats.  I know some people put in capacitance senders, but this seemed so simple and basic that I didn’t want to stray from the plans.

   

Then it was time to seal up the rear baffle on the first tank.  I was pretty nervous.  I checked everything multiple times.  I had a lot of trouble, though, with the pull rivets.  I kept getting sealant in the puller which would then seize.  My trusty Stanley puller gave up the ghost, but I finally got everything pulled.

I took the first tank home to do the leak testing.  I put the balloon on and it seemed to hold air.  I took a dip in the pool and checked back a couple hours later and found that it was totally flat.  That weekend, I got some bubble juice to try to track down the leak.  It was at the balloon joint itself.

So off with the pink balloon and tube and on with a directly connected green balloon.  I added a little Gorilla tape to buffer the clamp so that it wouldn’t cut the rubber.  This one held for 24 hours.  One tank done!

So I did the second tank last weekend.  Brought it home.  Put a lucky green balloon on and….

There was a definite leak at the corner of tank inboard rib and the tank attach bracket.  Sigh!

It could be worse.  I think that I can vacuum in some thinned sealant to get a better seal (or maybe some LockTite).  If that fails, I can reach it by taking off the fuel level sender (yuck), but at least there is a hole that I can reach it through (or a tube attached to a syringe anyway).

In preparation for attaching the tanks and leading edges, I worked on finishing the leading edges.  I had skipped fitting the landing light lenses because it was cold (in NY!) when I last touched these.  It was a balmy 96 degrees F in the afternoon, so I was less worried about cracking.  The first lens has a small gap.  I hoped that I would get a better fit.  I’ll just use some silicon or something to make it watertight after final install.  The second on went on very nicely and I achieved a nice fit around the leading edge.  I changed my technique for the second one and drilled and clecoed the holes directly into the lens after the first rough cut (3/4″ margin).  This let me push harder on the lens from the inside and get that tighter fit I was trying to get.

So next steps are to patch the leaky corner in the second tank.  I’m hoping that it won’t be too hard to get to.  It takes a while though between iterations since I have to let the sealant cure a bit before testing.

Next, I will do the first rough assembly of the wings and fab the control rods.  There’s also a service bulletin that I need to get to that increases the doubler at one of the control mounts. I may even get the pitot mast mount installed.  I’ll wait to close up the bottom skins for a while so that i can get started on the fuselage.

 

Fuselage is here!

Not a lot to post, but my fuselage kit was just delivered… Of course I thought the wings would be almost done by now.

I was supposed to get a call from the trucking company to give me an hour heads up before the delivery, but the call never came. I headed out to the hangar at 3:30 because the kit was supposed to arrive by 5pm and traffic was building.

Finally, after 3 calls to dispatch, they got a hold of the driver who had been delayed by an exploding pallet.

Got it off the truck and into the hangar. Then I had to run because the wife and I had tickets to "39 Steps." Made it with time to spare!

A not very auspicious start to the tanks…

My wife was out of town for the week, so I figured to get some extra shop time in.  I spent a couple of evenings finishing up the prep work for the tanks.  My hangar neighbor John was going to help me get started.  He was an F-16 crew chief and had some familiarity with the grey goo they call tank sealant.  It seemed better to have a go at this with someone who used this before.  The Rans Raven he’s building has a roto-moulded tank, so he had it a lot easier!

The tank skins were slightly deformed from sitting out so long.  The nose was decidedly more pointed than round, so I did a dry fit of the ribs to see if it would come back into shape.  That part worked out, but it was slow going just to get the ribs to line up.  I made a rib shaped spreader that helped some and I polished and pointed my bent up 3/32″ pin to make a drift pin.  With the ribs in place, the pointy-ness disappeared and I got a good fit.

I still had a little prep work to do on the end ribs.  I riveted on the nut plates (used to secure the fuel tank float).  They didn’t need any sealant because I’ll form a tank sealant gasket when I do the final install later.

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Then I cleaned up the edges of the anti-rotation collars that hold one of the fuel fittings in place.  I decided that it would be a good idea to check to make sure that the nut fit into the collar correctly…. It very much did NOT!  I had to file and clean the edge quite a bit to get a good fit.  This would not have been very easy to do once the fitting was installed on the rib (would likely have had to drill it out and re-mount it!).

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That gave me all the parts I needed to get started!  In anticipation of John’s arrival (he is SO not a morning person), I got everything prepped and laid out.  I pulled the sealant out of the fridge (keeping it frozen or cold prolongs the shelf life), set up the C-frame to rivet the tooling holes closed, and got my dixie cups and popsicle sticks ready….

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At this point, I don’t have a lot of pictures because my gloved fingers were covered in sticky grey goo.  But I can tell you, it did not go well at all.  We started by trying to rivet in the VA-141 fuel flanges.  I tried a squeezer, but the rivet set caught on the edge and I couldn’t get a straight shot at the rivets.  I tried shooting the rivets instead, but I ended up clenching them AND distorting the flanges.  We tried drilling out the rivets, but we ended up messing up the holes.  We declared the whole adventure a total loss.  I’m ordering new parts from Van’s and we’ll try it again.

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So, with that out of the way, we moved on to the really expensive parts!  There are 11 stiffeners to install on each skin.  You have to make sure that each rivet is well coated in goo before pushing through the holes.  We used clear packing tape to hold the rivets in place and back riveted the stiffeners in.  This was the first time John had seen back riveting.  I like it because I always get such nice, clean rivets.  The first 10 stiffeners went really well.

Now all this time it is really raining as a huge storm cell passed right over head (much better building day than a flying day).  I closed the big hangar door because the rain was pushing inside.  John went next door to close up his.

While he was over there, I set up the 11th stiffener, prepped the holes, taped the rivet line, slipped the stiffener in place…. Then I looked down.  There was water FLOWING though the hangar.  It was pouring through the bottom of the wall seam and running a half inch deep in places.  This was not a good day to have my electrical cords down on the ground!

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Then the power went out!

The power came back on again a couple minutes later.  I was just prepping to rivet the last stiffener anyway (air powered!) with a headlamp.

So I spent the next hour pulling boxes and electrical off the floor and sweeping water out of the hangar.

Sigh!

I’ve ordered new end ribs and flanges.  They’ll come with the fuselage kit that will show up in early August (it also contains a new horizontal stabilizer skin — the old one had a big ding in it from an early back-rivet fail).

I won’t get a chance to get back to the shop this month since I’m taking a trip out west for my niece’s wedding.  It will be nice, some day soon, to do those trips in the RV-14!  But for now, it will have to be commercial.

When I do get back, I’ll rivet the stiffeners into the left tank, seal the rivet lines, and get ready to start putting ribs in place.  They’ll be tanks soon enough.

Tank attach brackets

I finished up countersinking the fuel cap brackets and moved on to the tank attach brackets. These have a bearing, some shims, and three different kinds of nutplates that need to be attached.

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As always, first I had to find everything.  I had put the shims by the brackets themselves when I was hunting up everything at the start of the chapter, but it took a while to dig out all the nutplates.  The MS21051-L08’s in particular were a bear to find.  They are in bag #3015.  They are the only nutplates in there.  The spreadsheet of parts was very helpful! I separated the shims on the bandsaw and carefully deburred the holes (the instructions note to do a good job with this, particularly on the #8 screw holes).

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The shims have to be trimmed to match the ends of the attache bracket.  The narrow shim in particular has a very slim edge clearance to the outer nutplate hole.  I carefully sanded them down on my sanding disk to get the a close clearance.

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I marked the “primer line” on the attach brackets and started clecoing the nutplates in as I found them.  I’m substituting K1100-08 for the K1100-08D because I’m going to use “oops” rivets instead of dimpling the tiny shims.  I’m afraid that the shims will warp badly in the dimpler.  The hole on the end, in particular, is way too close to the edge for my to think about dimpling.

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I filed the cut marks off of the brackets before running them through the Scotch  Brite wheel.  The initial edge was a little sharp.  So I donated a few more drops of “Blood, toil, tears, and sweat” to the project.

The RV-12 was feeling a bit neglected.  The early low clouds had finally risen.  My son Ryan came down for the afternoon, so we fired up 3EN and did some pattern work.  He is getting ready to start his flying lessons, so I let him do one of the takeoffs and one of the landings.  He did a great job!

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I primed up the external parts of the brackets and shims and countersunk the brackets.  The picture shows a test fit.  The bracket lays tight to the skin and the shims have sufficient clearance.

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The final step for the day was to rivet the flange bearings onto the brackets.  This is where I really like working both right and left together.  I’m able to make sure I’ve got everything set up correctly.  The nice mirror image gives me some assurance that dyslexia didn’t bite me here.  I don’t show the riveting, but it came out pretty nice.

I have a few more things to finish up before diving into the Proseal.  I have to rivet some nutplates to the shims and then the shims (with more nutplates) to the brackets. I’m using the NAS 1097 rivet trick here rather than dimpling to avoid warping the shims.  I got the light countersinks done, but then had to jet to meet my wife for BBQ at Killen’s.