Left Tank Vent Line

Super short session tonight.  I came back in town from being on the road, and wanted to get something done on the build to keep the progress going.  I left off with the left tank clecoed back together so I can start working on the last bits and hardware,  and this session I decided to get the vent line cut and ready to go.  I pulled out the stock of 1/4″ soft aluminum tubing which came with the wings.  Vans sends 19 feet of it most of which goes for the pitot system, but I am going with a different system for pitot and AOA, so I will have PLENTY of extra to play with.  I uncurled enough tubing to give me about a foot extra of vent line for the left tank. Then straightened it out and feed it through the holes in the ribs.  I removed the inboard rib since I need to drill a hole for the fitting.

Next up was to locate and drill the hole for the elbow fitting.  This is the plans for the fitting, and the rough location of where to drill the hole for it.

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So, I made a mark in the rough location of where it shows in the plans, and then drilled a #30 pilot hole.  Then opened the hole up to the proper size for the AN833-4D bulkhead elbow with a stepped drill bit.

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Since I am going to install capacitive senders in my tanks, I needed to notch out the bushings that the vent tube slides into in order to make room for the wiring.  I used my chainsaw sharpening file to notch out the lips in the SB437-4 bushing.  To make sure, I fitted the bushings on the vent line and inserted the wiring checking there was enough clearance.

I need 5 of these for the ribs in each tank, so I went ahead and notched out 10 of them, which is enough for both tanks.  Then, I snapped five of the bushings into the ribs for the left tank after I had deburred the holes for them.  After that, I threaded the aluminum tubing into the ribs, through the bushings so that I could get it lined up and cut to length and flared.  I need to pick up a tubing cutter before I cut to final size. My tool kit came with a nice Parker flaring tool but not a cutter. heh.  So, I’ll order a tubing cutter this week and get it ones its way.  Heres where I ended up tonight:

Thats where I leave it for the night.  I’ll get a tubing cutter on the way, but I can start working on the capacitive senders while its being shipped.  I left my tubing a little long to give me some room for margin, and I also have some scrap tubing to practice cutting and flaring on before moving on to my “production” parts.

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Google Photos Link: https://photos.app.goo.gl/zYoputXmk6761L2H6

Hours Worked: 0.75

Anti-hangup Brackets and Fixing the Trap Door and Anti-rotation Bracket

I told myself this was going to be a quick sesison,  just finish up the anti-hangup brackets and we’re done for the night…….it didn’t happen that way :-0 I actually ended up doing a LOT of work, 3.5 hours worth, but I am glad I got it all done.  At this point, I am ready for the fuel vent tube, and the capacitive senders.  I started this one off by making the anti-hangup brackets that keep the flop tube from getting stuck on the nutplates for the access panel.  Van’s wants us to make a simple one by riveting a piece of .020″ alclad onto the back of the reinforcement plate, but that would block any easy access into the tank if you ever needed it.  So, a bunch of clever builders came up with ways of making anti-hangup brackets that attach to the access plate, and come out with the access plate so as to give you full access through the hole when the cover is off.  Thats how I am doing mine.  It takes a little more time to do it now, but its worth it if you ever need into your tanks. I went through a few different iterations, and several pieces of scrap became smaller pieces of scrap in the process, like below:

But, eventually I came out with something like this below.  I used .025″ alclad, cut to about 3/4″ wide and long enough to fit from the top of the tank to the bottom with a little bit of clearance.  Then I made some Z-brackets out of the same alclad and bent them so they could be riveted on to the access plate, and give enough room that you could work the bracket into the fuel tank while it was attached to the access plate.  Here is my rough layup.  I am using packing tape to hold things together as I trimmed, and adjusted everything.  It worked pretty good as it was easy to move around and held things nicely.

Here’s what it looks like when the cover is in the tank, and the flop tube is resting against the anti-hangup bracket. You can see how well it holds the flop tube away from the platenuts and anything else that it could snag on.

Here’s a quick video of the layout process:

Once I had it where I wanted it, I left everything taped up and then drilled the holes for the Z-brackets into the access plate.  After cleco’ing those into place, I then drilled the holes to attached the anti-hangup bracket onto the Z-brackets.  I am going to use flush rivets for these to keep a nice smooth surface for the flop tube to ride against, so I will deburr and dimple these as well.

I decided to use flush rivets here to hold the ant-hangup bracket assembly to the access plate, so that I could easily get my long nose flush squeezer yoke in there to squeeze these rivets.  These rivets will also get prosealed since they are penetrating the tank.

I did go ahead and deburr all the edges and new holes on the assembly, as well as dimpling the Z-brackets and anti-hangup piece.  I then machine countersunk the access plate to accept the dimples from the Z-brackets.  I went ahead and riveted the anti-hangup to the Z-brackets since its safe to do so at this time. And this is how it came out!

Here’s a video after everything was completed, and showing why and how I did it this way.

One thing I noticed was that my anti-rotation bracket on the flop tube didn’t allow me to easily remove the flop tube if I ever needed to change it.  It actually held the fittings from turning, which meant I’d need to drill the bracket out if I ever decided to change the flop tube.  Now was the time to fix it, while it was easy and no loss.  So, I trashed the old bracket, and made a new one, placing it a little further down from the fittings that screw onto the 90′ elbow.   It was a simple thing to make, using some angle aluminum just like the first one.   I marked out some lines for my edge distance, and them trimmed out a section to fit around the red portion of the flop tube.  Then drilled two holes to attach it to the rib.

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Here’s how it works.  The red nut is where the flop tube rotates freely on its fitting.  We don’t want the fittings to turn when we tighten them down, nor do we want the flop tube rotating anything when its flopping around during acro.  The blue fitting is where we put a wrench on to tighten the flop tube down onto the blue 90′ elbow fitting.  with this setup, I can use a wrench, loosen the blue nut, and pull the flop tube up and out of the anti-rotation bracket, for easy removal if I ever need.   I like this setup WAY better.

After completing that part, I decided I wanted to remake my little trap door that holds the fuel in the inboard bay during acrobatic flight.  I wasn’t really happy about my trimming job on it, so I figured I may as well go ahead and re-do it while it was easy to do.  So, I drilled out the three rivets on the old little door, and cut a new piece from 0.25″ alclad per the plans dimentions of 1.75″x1.75″.  Then, since I already had the tank and ribs clecoed together in the stand, I thought it’d be best to go ahead and test fit my trap door with the skin and make it perfect.  The old trap door is the one on the bottom of the photo below.  I wasn’t happy with my trimming job.  The new one is the one in the top of the photo.

 

It fits WAY better now.  Sometimes its best to re-do your mistakes while its easy, even if they are not really a bad mistake in the first place.  My original, janky trimmed door probably would have given great service, but it bothered me everytime I looked at it. HAH!  I am much happier with this new version.  It sits really close to the skin so it will seal up great when I am doing acro.

   

I went ahead and riveted the top hinge to the rib, since I was 100% happy with the door.  I can simply pull the hinge pin out and remove the trap door and put it on the shelf until I am ready to close up the tanks.  The only other thing I done tonight was install all of the ribs into the fuel tank and cleco them in nice and tight.  I need to cut the vent line and install the capacitive sender plates, and I want the tanks assmebled to do that work.

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Google Photos Link: https://photos.app.goo.gl/2mXa67zZcnzU8E6eA

Hours Worked: 3.5

Right Tank Access Plate and Anti-Hangup Brackets

Picking up from my last session, I decided to go ahead and finish the right tank access plate.  I had already cut the access hole in the rib when I was working on the left tank in the last session, so I really just needed to do a little to finish this up.  I also started out on the anti-hangup brackets too. Since the right tank will be getting a normal pickup tube, I can place the fuel level sender in the stock location and use the T-708 tank access plate that is pre-punched for both the pickup, and the fuel level sender.  So, It’s just a matter of aligning it with the tank access hole, and clamping it in place.

I made sure to attach the fuel pickup, its fittings and anti-rotation bracket to the access plate so I could make sure i had everything in the proper orientation as well as in the proper locations so that the fuel pickup sat as low as possible.

You can see in the photo below, I have the pickup as low as it can go to pickup the most amount of fuel in the tanks.  I am using the pre-built fuel pickup from Van’s because its cheap, well made and simply fits into place with zero effort.  It’s a no brainer!

Once I had the access plate in place, I used it as a template to back drill the screw holes into the rib.  This was just the same procedure as my last session.  I’d drill a hole, and then stick a cleco in to make sure nothing moved, and everything was tight and aligned.

Once I had the rib back drilled, I removed the access plate, and then clecoed on the T-407 reinforcement plate, as I needed to use it as a template to back drill into the rib for the platenut attach holes.  So,  I cleco’d it on, and then drilled the #40 holes into the rib using the plate as a guide.

Once I had all the holes drilled, it was time to deburr everything and then dimple the holes in the rib, and machine countersink the holes in the reinforcement plate.  For details on this see my previous post on the left tank…same process here.  Then, I re-assembled the reinforcement plate onto the rib, clecoing it on with its platenuts, so I could rivet them.

The squeezer made quick work of these guys, and after a few minutes, it came out looking great!

Since this work didn’t take long, I decided to go ahead and start working on on the anti-hangup brackets in the left tank for its flop tube.  We need these little brackets fabricated so that the flop tube won’t get hung up on anything in the tanks as its flopping around.  They are simple to make, and the plans calls for them to be made like this:

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So, I re-assembled the left fuel tank, using the 3 most inboard ribs to hold the shape so I could get these made correctly.  You can really see why we need those brackets here! There is potential for the tube to get hung on the nutplates, and between the rib and stiffener on the outboard side.

I went digging in my scrap bucket again for some .025″ alclad to make some brackets, measured out a ~1/2″ wide piece and started forming it to make the ant-hangup brackets. I ended up going through three iterations before getting this right, as the alclad would crack when I’d go to bend it to the shape needed.

 

These are my first two iterations, headed back to the scrap bucket!

I wound up using some clamps to hold it in place on the stiffener while I made the bends and checked everything.  Then I drilled a #40 hole in the piece mounted onto the rib where I’ll rivet it in place during final assembly.  I did the same on the bracket through the stiffener, which will get riveted during final assembly.

And that was all I had the energy to do tonight.  Tammy was making a nice smelling dinner (Taco Soup!), and I couldn’t resist anymore.  I went upstairs and ate dinner with the family.  I’ve got some plans for the anti-hangup bracket on the access plate, but it’ll take some fabricating so thats a good start for the next session.

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Google Photos Link: https://photos.app.goo.gl/hhhbfBJ4Sez1Utez9

Hours Worked: 2.75

Fuel Tank Access Plates

I had to pick up a tool to help with cutting the access plate holes for the fuel tanks.  Vans recommends using a fly cutter to cut the access holes, and I thought I had one.  Turns out, the fly cutter I had was for cutting holes in drywall, and would not work on metal.  So I swung by Ace Hardware and picked out one of these for about $22 bucks:

It’s designed with a carbide tip thats suitable for soft metals.  And its fully adjustable.  It’s well worth the price.  So, to get things ready, I spent some time aligning the T-408 reinforcement ring and T-411 access plate per the instructions and making sure I had all the right clearances and measurements.  Then I traced out a line of where I wanted to cut the hole in the rib, to give me a reference to use for the fly cutter.  After chucking the cutter in my drill press, I used a piece of scrap plywood as a backer for the rib and to give the fly cutter something to cut into, instead of my drill press 🙂

Then I adjusted the fly cutter to line up with the blue cut line, making sure to slowly turn the chuck by hand to make sure I had the rib centered up on the cutter.  This took me longer than it should have, and I am sure there is a better way of finding and marking the center of a hole, but this worked.

Then I set my drill press on its slowest speed of about 240 RPM.  You don’t want to use a fly cutter at high rpms!  Once I was ready to go, I slowly and gently pressed down on the fly cutter and let it do its work.  It makes a HELL of a racket, so just go slow and gentle with the quill pressure and it will make a nice neat cut.

 

I went ahead and cut the access hole for the left wing tank as well, since I already had the cutter chucked and adjusted.  I did it the same was as the right, and it came out great as well. Next up, we need to back drill the screw holes for the T-411 / T-708 access plates.  I decided to start on the left wing tank, since I need to finish up the flop tube anti-hangup brackets, (more on that in a few posts).  Since I am using a flop tube in the left tank, I wont be mounting the fuel level sender on the access plate as per the plans.  So, I am going to use a T-411 access plate on the left wing, which is a standard plate that does not have pre-punched holes for the level senders, or fuel pickup tubes.   So, I got the part from stock, and lined it up on the rib making sure the flat part of the plate faced the little bump on the rib as per the instructions.

Once it was lined up, I clamped it down tight and then used the pre-punched screw holes in the T-411 plate to back drill into the rib, clecoing the new holes as I went.

Once I had them all drilled, I removed the T-411 access plate, and then clecoed on the T-407 reinforcement ring using the new holes in the rib for alignment.  We need to drill the #40 holes use for the nutplates.  Straightforward this part.

I used the larger, black colored clecos to hold the T-407 in place so I could back drill the #40 holes using the T-407 as a guide. Eventually I wound up with the rib fully drilled. The next thing to do was deburr all these new holes, and of course deburring the sharp edges of the newly cut access hole with some scotchbrite.  I also ran the T-407 and T-411 on the bench grinder to get those edges nice and smooth as well.  Next I dimpled ONLY the #40 holes that are used to hold the nutplates in, making sure to get the dimple going in the right direction.  We have to machine countersink the T-406 to accept these dimples due to its thickness.

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The instructions tell us we can go ahead and rivet on the nutplates without sealant because there is a cork gasket that will be used on the outside of the access hole that seals this section.  So, I clecoed on all the nutplates and started squeezing them with my squeezer.

And here is where I made two mistakes for the night, and had to drill out some rivets.  The first mistake was I squeezed a rivet, without making sure it was actually going through the hole in the nutplate!  Such a boneheaded move. HAH.

Shortly after that, I smushed a rivet over because I didn;t have the squeezer set squared up and centered.  Thankfully, I have gotten pretty decent at drilling out rivets by now, so I simple drilled these mistakes out, and cleaned up the holes and fixed those mistakes pretty well! The blue lines are where the bad rivets were at 😉

That finished up the left wing tank access holes.  After making those two mistakes, I figured it would be best for me to call it a night to prevent more from being tired.  This is a good stopping point, and I’ll pick up on the right tank access plate next time.  Then I’ll move on to building the flop tube anti-hangup brackets.

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Google Photos Link: https://photos.app.goo.gl/HsMA36nfyKSgNr3U8

Hours Worked: 2.25

 

Installing the Flop Tube

After a quick break and bite to eat, I went back down to do some more work.  I decided to go ahead and get the flop tube installed for now, and do the capacitive senders in the next session.  I’m only doing a flop tube in one tank: The left tank, so I’ll be sure to placard the fuel selector as “Acro on Left Tank Only” just for the cool factor of it.  The real reason is that there is a good bit of extra work to get the flop tube installed, and you have to move the float fuel level senders out from the access panel to one of the inner fuel bays, making it damn near impossible to service it if needed.  Thats one reason I am also installing capacitive fuel sender plates in my tanks, they’ll give me a backup fuel level source, and they are pretty easy to install during assembly and they need zero maintenance.  So, I’ll install both capacitive and float senders in my tanks.  The right tank will have the standard Vans fuel pickup, and it’ll be standard assembly as well.

The session starts of with trying to find a good location on the tank attach angle brackets to drill the 9/16″ hole for the flop tube bulkhead fitting.  I tried to center mine up as much as possible, while also trying to keep the flop tube as low as possible, but it was a compromise.  Here is where I decided:

I made a circle using the inside of the blue bulkhead nut as my guide to find a spot.  Then I drilled a pilot hole using a #30 bit.  This hole went all the way through the T-405 tank attach angles, the T-703-R rib, and the T-410 reinforcement plate.  Then, I chucked up my step drill bit in the drill press and drilled the holes out to the proper 9/16″ size.

  

I put some masking tape on my flop tube to keep trash and debris out of it, and also to protect the little rubber o-ring bumper during the assembly process.  I wasn’t very happy with the way the anti-rotation brackets from Vans worked out, as I didn’t have enough room to fit one of them. The plans don’t call for an anti-rotation bracket on the flop tube, but does have us safety wire that fitting.  That safety wire will only keep the fitting from rotating, it wont stop the actual bulkhead from rotating as the flop tube…flops. So, I decided to fabricate my own bracket.  They are simple enough to make, and I had plenty of stock angle to work from.  This actually took me longer than I had thought it would to make, and I went through several iterations before I had one I was happy with.  Thank goodness I had plenty of angle stock to work with!

I angled my flop tube and its associated anti-rotation bracket slightly downward so that the fuel pickup would rest as low as possible in the fuel tanks.  It will still flop around perfectly fine and pick up fuel in the inverted and knife-edge flight attitudes.  Here is the anti-rotation bracket clamped down and getting drilled into place.

And below is what I eventually ended up with.  The rounded section goes against the rounded shoulder of the bulkhead fitting with a few 16ths clearance, while the squared end is roughly 11/16″ which is just slightly bigger than the flats on the fitting.  This way, when I tighten the flop tube up on its fittings, I can rotate the flats to line up with the bracket, which will serve double duty:  Keeping the flop tube from rotating around the where the bulkhead goes, as well as keeping the fitting from rotating counterclockwise and loosening itself off the threads. I actually notched the bottom of the bracket so that the points of the fitting would sit nicely down in it, giving me good clearance.  I am actually pretty proud of this little bracket!  It’s really simple, but took quite a bit of learning and work to create.  I will be much better at making them if I ever decide to build another RV 🙂

I wish I had snapped some more photos of the actual process of making this silly thing, but I kind of got into the “zone” and forgot to take some until it was nearly done.  The little black marking on the upper left of the bracket is where I needed to trim the corner ever so slightly to make room for a rivet that is in a nearby hole.  I did indeed make that trim and then tested it for fitment.  Next up was to fabricate the trap door that holds the fuel into the inboard fuel bay so it doesn’t drain outboard when you are inverted or doing knife edge flight.  The plans tell us to make this out of some 0.020″ alclad thats 1.75″ x 1.75″ and a piece of piano hinge. We have this to go by in the plans as well:

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Which is pretty easy to go by.  So, I went digging in my scrap bucket for some 0.020″ alclad, marked up a little piece and snipped it out with my snips. I did the same for the piano hinge, luckily I had a piece almost the right size in my scrap bucket.

Then I measured for edge distance, and marked a reference line, broke out my rivet fan spacer and marked up three rivets holes, then drilled them.

     

Once I had the trap door drilled, I trimmed my piano hinge and fitted it where it would work best, trimmed it to the right size and bent the little tang to serve as a stop to keep the flap from flopping all the way up. I also decided to cut a little spacer of 0.020″  to go behind the top hinge to help the trap door sit totally flush against the rib.  If i hadn’t done this, the top of the hinge would have been sitting right against the rib. while the bottom of the hinge would have been angled slightly because of the flap riveted to it.

Then I dimpled the flap and the hinge so I could use flush rivets to help keep the flap sitting nice and flush against the rib.

Finally, I riveted the flap onto it’s section of hinge using my squeezer and some AN426AD3-3.5 rivets and clecoed it onto the rib with the spacer behind the top portion of the hinge.  You can see how it works now.  The spacer is the same thickness as the flapper on the trap door.  This keeps the hinge pieces at the same height, and lets the trap door flapper swing very freely, and sit totally flush against the rib.

I also trimmed around the flapper a little towards the bottom, to keep the flap from getting hung up on any stray proseal that may happen to get down there when its time to seal it up. I want this little door to be able to swing totally freely, and then close completely when needed.

I decided to block off the hole in the inner rib.  Some builders do this, and some don’t.  For me, I want that inner fuel bay to be sealed off so I can do sustained inverted or knife edge flying.  If I left this hole unblocked, that would allow fuel to drain back to the outboard side of the tanks, away from the flop tube in some flight attitudes.  In addition, it looks like the flop tube may actually get caught in the hole in some situations.  So, closing it up is pretty simple:  a 4.5″ square of 0.020″ alcald and a few rivets.  I measured and cut some of my scrap alclad, and marked up the rivet holes with edge distance in mind.  Then I drilled the holes in the plate.

Once the holes were drilled and deburred, I went ahead and dimpled the blocking plate as well as the ribs so I could use flush rivets on the inner side of the fuel bay, giving even more less things the flop tube could catch on.   I used some AN426AD3-3.5 rivets to attach this blocker plate to the rib, making a nice flush surface for the flop tube to rub against, while at the same time, blocking any fuel from leaving my inner fuel bay when flying knife edge, with the left wing low, and the trap door flapper closed.

I’m really pleased with how this came out. I spent a good 4 hours or more just fabricating and fitting these parts.  I still need to fab and install the anti-hangup straps that go in the tank to keep the flop tube from hanging on certain bits.  But, I was out of steam for the day, and figured that would be a good “Part Two” for my next session.

 

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Google Photos Link: https://photos.app.goo.gl/iTp5eMERkYinN43e7

Hours Worked: 4.25

Drilling the Tank Angle Attach Brackets

Short session to start today.  I wanted to get the tank attach angles drilled, and after doing some reading last night, this actually seems straightforward.  Vans gives us a rough idea of where to drill the rivets for the angle attach bracket in the plans with this drawing:

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We just need to be cautious of edge distance, so I used my square and made a few lines to give me plenty of edge distance, and then drilled the brackets with a drill press to get the holes nice and straight since these are chunky bits of metal.

Then I deburred these holes, and placed the bracket into the rib and lined it up and nice and square so that I could use the bracket as a template to back drill the holes in the rib.  I used some clamps to help hold it in place.  Notice that I left off the reinforcement plate that goes on the back side of the T-703-R/L rib. I did that on purpose so it would be easier to line up.

With the bracket lined up and clamped, I simple back drilled into the tank rib using the bracket as my template.  Once I had the rib drilled, I removed the bracket and then placed the T-410 reinforcement plate on the inside of the tank rib, and lined it up.  Once it was lined up where I wanted it, I clamped it down and used the newly drilled holes in the T-703-R/L tank ribs to back drill into the T-410.

Now that all three parts were drilled, I clecoed everything together to make sure it all fit, and then double checked alignment.  It looked pretty good, so the last thing to do was to deburr all thees new holes and then move on to the outboard rib.

The outboard ribs were much simpler to do, since we don’t have the T-405 angle attach bracket to worry with.  We simple just need to align the T-410 reinforecment plate on the leading edge of the rib, on the inside of the tank, and then choose 3 to 4 rivet holes and drill.  Again, vans doesn’t give much guidance here, so I simply measured for edge distance, gave myself another 1/16″ for a buffer and then tried to space the rivets out in a decent pattern, then drilled the holes through both parts while they were clamped.

Once the outboard side was drilled, I removed everything and deburred the holes.  I think I did the left tank first, but after I had one tank done, it was time to move on and do the opposite side in the exact same manner.  Like always, the second time goes much faster, and I didn’t take any photos of it, since its the same as the other side.  Time for a quick break for a bite to eat, and then I’ll do another session tonight.  Probably either the capacitve senders, or the flop tube.  These are the fun parts of the build!

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Google Photos Link: https://photos.app.goo.gl/WkDGgx4wffPUXRXM7

Hours Worked: 2.0

Fabricating the Tank Attach Angles

Its time to fabricate some parts! I got home from having dinner with some friends and my family, and felt like knocking out a little bit more on the project, so I decided to tackle fabricating the T-405 tank attach angle brackets.  The plans are a bit vague here, as the instructions tell us to simply fabricate the brackets using the drawing in 16A and this is all we have to go on:

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So I went digging in my parts shelf and pulled out the 2 x 2.5″ 3/16 angle stock that Vans includes in the kit.  Then I marked off a 3 and 3/4″ section and cut it out on the band saw.

Next up, I wanted to cut the radius part out.  This is the part that goes onto the fuselage to bolt the tank on to the aircraft, and after reading a few other builders blogs, it appears there is some flexibility in how these are mounted so we don’t have to worry about alignment issues per se.  To cut the radius, I first marked off the center of the bracket as a reference.  Then I measured the 1″ radius as the plans call for as “R1″ by marking down from the tip of the bracket 1″ This gave me a crosshairs to form my 1” radius around.  I placed the point of a compass on this crosshairs, and started at the top of the bracket and marked with my compass until I was slightly passed a 45 degree angle on each side of the middle line.  This is sort of eyeballing.  Once I had a rough radius, I simple used a straight edge to mark from the stop of my radius down to the corner of the bracket.  It looked like a good angle when I marked it all up, and it looked very similar to what the plans was calling for.  See for yourself:

That took care of the TOP portion of the bracket, but I still needed to mark the bottom portion so it would fit snug against the curve of the ribs.  Vans gives us a T-410 reinforcement plate that is already cut perfectly, and it makes a very nice template to use on the tank angle brackets.  To make sure everything was squared up, I found the center of the T-410 to be right at 2″, so I marked the centerline of that bracket.  The T-405 angle bracket is slightly smaller, and its center line is at 1 and 7/8″ as seen in the plans, so I marked that centerline on the angle bracket.  Next it was just aligning the centerlines of the T-410 and T-405 to make sure they were squared up and in the proper orientation, and then use the T-410 as a template to mark my cuts for the T-405 angle bracket.  Here you can see how I did this using some cleco clamps to hold everything.

And here is what the copied line looks like on the T-405 tank angle bracket after you remove the reinforcement plate that was used as a template.

The next step was to cut these parts along my lines on the band saw.  I used a scrap piece of wood 2×4 to help hold the angle and keep my hands clear. I wished I had gotten some photos of this process, but I didn’t have any free hands, and I was concentrating on making these cuts.  However, its pretty simple and easy to do on the bandsaw, but I’d recommend not letting these be the first thick pieces of metal you make a curving cut on a band saw with if you have no experience.  I’m not a novice with a band saw, but I have made some complex cuts with one on metal, just take you time and go slow so as to not bind the blade.  Remember you can always work you way into the cut pieces at a time if you need to.  I also started OUTSIDE of my marked lines, so I’d have a little extra material to work with on the grinder to finish with.  After I had my rough cuts made, I finished up the parts on the grinder, working away the extra metal until I was right at my marked lines.  Here is what it looks like:

And after a few test fits, and visits back on the grinder I had a part that fit fairly good!  Once I was happy with the fitment, I went back to the grinder and rounded and smoothed all of the edges for the T-405 tank attach angle brackets.  These look like some sort of machined part with the crazy curves they have, but its a simple angle cut and smoothed 🙂

The only thing I am worried about is how I am gonna get to the rivets in the holes around the edge of the brackets (see photo above).  There isn’t much room for the rivet tail in there between the flange inside and the tank angle bracket.  I’ll do some research and see what other builders have done, as well as read ahead in the plans to see if this is going to be an issue.  It may be that I just notch out a little section for the rivet tail to fit into and call it a day.  After getting one bracket made up, I went ahead and moved on and did the same thing for the right tank brackets.  These were pretty much mirrored of each other, so the second one went a little faster than the first.  The plans tells us to go ahead and drill the rivet holes for these parts (T-405 angle bracket, T-410 reinforcement plates and the T-703-L/R ribs), but I am going to wait on that until I am sure about what I want to do about notching them first.  I’ll call it a night for now.

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Google Photos Link: https://photos.app.goo.gl/77eEx2AzRojMogfLA

Hours Worked: 2.0

Finishing the Leading Edge Ribs

My Vans shipment came in while I was on vacation with the family.  The leading edge ribs I needed were in this shipment, these are the ones that will replace the ribs that had the edge distance issue from where I mis-drilled them.  I also had some proseal, 50ft of nylon conduit and a few other things I wanted to pick up; including the Vans lighted sign 🙂  I’ll build that later, dont want to use up my time on the RV-7 building the sign.

First things first:  In this shipment was one of my missing K1000-3 nutplates that I needed on the aft spar web of the right wing, so I spent a few minutes riveting that nutplate on using the back rivet method.  Once I had that done, I needed to get these new ribs ready to be used.  That meant straightening the flanges, and fluting them, deburring, and all that good stuff.  So, like so many posts ago, I set about deburring the edges of the ribs using my bench grinder, and then a combination of scotchbrite, sanding paper and emory cloth to get all the tiny gaps in the flanges.  Then I used a deburring tool and a scotchbrite to deburr the edges of the lighening holes.   Once they were nice and smooth, I used this handy tool I made a while back to get the flanges to 90 degrees.

   

Before correcting the flanges

After correcting the flanges

Then it was time to do some fluting to get all the warping out from the forming process. I outline this in detail in previous posts, but here I am using my wifes granite countertop as my flat surface to check the fluting process against:

You can see a big difference!  The top pic is after its been fluted and all corrected. Once I had them all straight and ready to go, I marked the centerlines of the flanges so I could line them up with the prepunched holes in the leading edge skin to make sure I got the correct edge distance, then I back drilled into the ribs using the skin as a guideline.

It’s not 100% perfect, but its close, and there is plenty of edge distance now, so I am happy with the outcome.  I tossed the old ribs into my scrap bucket, maybe I’ll find a use for them in the future?  I then removed the ribs and the reinforcement plate and deburred the holes on both the rib and the plate.  I’ll leave these parts off for now, because I need to alodine them before final assembly.

I wanted to get a little more work done, so back to the tanks! It’s time to make the tank attach brackets.  I separated the T-407 and T-410 from the assembly so I could work on them.  Then I deburred all the edges of these parts on the bench grinder / scotchbrite wheel and labeled them for each fuel tank.

That was it for this session.  Here’s another pic of me, to show I am the guy building the airplane:

And heres an album of all this sessions photos.  I’m headed out to meet some friends for dinner with Acacia and Tammy, and if I get back in time tonight, I’ll continue working.  Next up will be to make the heavy tank attach brackets.

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Google Photos Link:  https://photos.app.goo.gl/hUMoEMcm4FR6FEYB9

Hours Worked: 3.25

Fitting Tank Drains and Fuel Caps

Tonight was a fun build session!  Since all the tank structure is pretty much fitted and done, I needed to knock out the last few little bits of tank parts:  The tank drains (sumps) and the fuel caps.  I’ve been sort of looking forward to doing this work to be honest.  I decided to start out with the easy stuff first and then work till I was tired.  That meant fitting the tank drains (aka “sumps”).  We need to center the VA-112 drain flange over the pre-punched drain hole in the tank skin and use the flange as a guide for back drilling the tank skin.  I didn’t want to eyeball this, so I pulled out my assortment of center punches and found one that was almost the same size as the hole in the drain flange and used it as a guide to center the flange on the skins hole.

Once I had it centered up, I used some vise grip clamps to hold it in place so I could back drill the skins rivet holes using the flange as a guide.  I’d drill a hole, and then insert a cleco immediately in the hole and then move across and drill another hole and repeat the process. This assured I’d have the flange nice and flush on the tank skin and everything lined up.

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After I had the flange drilled, I removed it, and then deburred the rivet holes with a deburring tool, and done the exact same process to the other tanks flange.  The flanges shipped machine countersunk, so I didn’t have to do any countersinking on them, but I did check their depth by inserting a rivet and making sure the head would be nice and flush.  I decided to start working on the next cool part:  The fuel caps.  I had ordered the upgrade Newton style “Deluxe” fuel caps when I ordered my wing kit, from the suggestions of many other builders, and these things are AWESOME!

They ship with a nicely machined flange that is shaped to fit the inside curvature of the tank skin, making fitting them pretty easy.  On these, the tank skins have pre-punched holes for both the fuel filler hole, as well as the rivet holes that is used to rivet the machined T-406B flange onto.  I decided to put my tanks in the stands and cleco in three of the outboard ribs to help the skin hold its correct shape, that way I could get the machined curve in the flange exactly right.

Now it was a matter of lining up the machine parts of the flange with the curve of the tank skin and then using the actual fuel cap as a guide to help center everything up on the pre-punch fuel filler hole in the skin.  Once I had everything lined up, I used some C-clamps to help hold the flange in place so I could get the first holes done.

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After I was happy with the alignment, I then started back drilling into the T-406B flange using the tank skins pre-punched holes as my guides.  Like always, I’d drill a hole, then insert a cleco into that new hole to help hold everything tight before moving on to drilling the next hole.  I only removed the clamps at the very last moment.

And VOILA! This his how it looks when its all said and done. I can’t tell you how good and how flush these fuel caps are!  They are really sexy and are very well made.  I’m also very happy with just how well sized the pre-punched filler hole was in the skins, as I didn’t need to do any sort of work on the skins hole to get everything lined up. It really made this look like a completely professional install.

  

 

 

 

 

 

 

 

 

 

You can see how well the flange’s machine curve fits against the skin! I also marked the flanges against the skins so I could get them returned to their correct orientation when it comes time to rivet them on.

And here’s a quick little video of how well they look and work:

Once I had all the holes back drilled into the flange, I went ahead and deburred the new holes in the flanges, and then used my micro stop countersink to countersink the holes in the TOP part of the flange so they could receive the dimples that will be going into the tanks skin.  I adjusted the countersink so that it would do a little deeper into this part as its very thick, and I wanted to give plenty of room for the dimple in this .032″ tank skin, and also leave room for some proseal to goop in the dimples for sealing.  Once I had one tanks fuel cap done, I did the same exact process on the others wings fuel tanks.

The last little step I enjoyed pretty well.  I needed to fabricated the T-714 clip for the vent line out of some 0.025 x 1/2″ wide sheet.  I dug in my scrap bucket, and found a nice sheet of alclad in 0.025, and marked out a 1/2″ wide strip along the edge, and then cut it off with my snips.

Once I had my strips cut, I had to form them into the shape that is denoted on the plans like this:

Next I marked a centerline on the strip so I could get the rivet hole just right, and then placed the centerline on the T-406B flange rivet hole to mark the hole onto the strip where I’d need to drill into it for its mounting hole.  Then drilled it with a #40 drill bit to match the flange, and formed a rough bend line to get an idea of what I should do.

Before going to far, I deburred the edges using my bench grinder and then rounded all the corners to prevent any stress cracks. For the bends, and even for the loop in the clip, I used a handy set of forming pliers to get nice and straight bends.

I then formed the loop in the T-714 clip using the aluminum tubing that will eventually be the vent line, as well as the forming pliers until I was happy I had a nice loop to hold the vent tubing.

Once I had one completed, I went ahead and done the other tank’s T-514 clip in the same manner, making sure to deburr the rivet hole and deburr the edges.  These turned out better than I had expected, and I am a little proud of how they ended up looking!  Too bad they’ll be in the tanks where no one will ever see them.  Hah!  That was enough for tonight.  That completed the cap and drain system for the tanks.  I still have a little more fabricating to do on some other tank parts, but thats for another session!  Here’s all the photos from tonights work:

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Google Photos Link:  https://photos.app.goo.gl/QACsSYvKd9Rra7877

Hours Worked: 3.5

Match Drilling the Left Tank

More Fuel tank work!  Tonight I wanted to get the left fuel tank match drilled and then disassembled so that I could begin working on deburring the parts and getting them ready for final assembly.  I already had the left tank off the wing and on the bench from my last session, so I started in by match drilling all the 3/32″ holes.

Once I had those done, I then started on countersinking the rivet holes that run the length of where the skin attaches to the rear baffle, as per the instructions.  We countersink these so that its easier to slide the baffle in place with the wet sealant during assembly.  If we had dimpled these, it would be much more difficult to do this evenly.  The micro-stop countersink was already setup for the proper depth, so I made quick work of those holes.  Next up was to open the screw holes that attach the skin to the spar and the W-423 strip to a #19 hole.  Once I had all the holes match drilled, I labeled where the parts were clecoed, disassembled the tank and set its parts on the shelf to be later deburred and finished.

There was one more step I needed to complete before moving on for the night, and that was riveting the nut plates to the spar web that are used for the most inboard tank attach bracket.  These are placed on the BACK side of the spar web, so that its easier to bolt the tank into place.  There are three pre-drilled holes in the spar web; one for each nutplate.  I simply clecoed them into place and match drilled the holes.

We need to attach these with AN426AD3-4 rivets so the head will sit flush on the spar web, so that the tank attach bracket can sit against the spar web.  So I used the microstop countersink, as it was already setup for the tanks depth and countersunk the holes.  Except I ran into an issue:

As you can see in the photos above, there wasn’t enough clearance between the spar reinforcement bars to get the pilot into the holes on the upper and lower nutplates.  So I got a bit creative.  I used a deburring tool in my power driver and very gingerly countersunk the holes, checking the depth every so often with a rivet until I had the rivet sitting flush:

This worked pretty good.  Then I clecoed on the nutplates, and riveted them using the backrivet method.  I used the back rivet tool in my rivet gun to press against the tail of the rivet from the inside of the wing and then the bucking bar on the flush head and bucked from the top.  This worked out really well.

 

I finished up the left wing, then moved on to the right wing, when I noticed:  I am SHORT by one K1000-3 nutplate!  I didn’t have enough to finish the last hole.  I need to get an order in to Vans anyways to get some proseal and other things on their way, because we are very close to sealing up these tanks!  So thats where I left it for the night: One nutplate short!

Google Photos Link: https://photos.app.goo.gl/vZy9N7VWABo1qbz78

Hours Worked: 3.25