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

Match Drilling the Right Fuel Tank

Had a really good build session tonight, and made some really great progress on my fuel tanks.  To pick up from where I left off last, I needed to back drill the tank ribs to the baffle and into the tank attach brackets.  I used my 12″ long #30 (1/8″) bit to back drill all the holes.  This worked well and I had plenty of room to work.  at 16″ probably would have been much better.

Next, I needed to remove the blue plastic from the inside of the T-701 tanks skins so to start the match drilling process.  I started on the right tank, and pulled the plastic off, then cleco’d on the tank stiffeners.  Just a side note, when you are cleco’ing the stiffeners on, dont use the very edge holes on the stiffeners and the clecos will give you a hard time around the ribs.  I had to move my clecos to make slipping the skin on a little easier. I also numbered the stiffeners and their location on the skins to make them easier to get in the right spots on re-assembly.

Then I slipped the skin over the ribs and clecoed it down.  PRO-TIP:  Start clecoing it down from the BOTTOM side of the wing, working your way from the center outwards and then around the leading edge and back down the TOP of the tank working towards the spar.  I fought with trying to do it the other way and it was a hassle!  Starting on the bottom side made it much easier. Heres the left tank clecod on as an example.  I only had enough clecos to do one tank at a time though.

Once the skin was compeltely clecod down to the ribs and baffle, we needed to back drill the W-423 plate using the tank skin as a guide.  We use a #30 bit at first to get the holes where we want. You can see the newly drilled holes in between the row of clecos in the photo below:

Once we have those holes drilled, we take the tank off the spar, completely assembled.  So, I unbolted the tank attach brackets from the spar, and moved it over to my bench to avoid match drilling into the expensive wing spar!  As is the usual process, I used a reamer to match ream all the pre-punched holes in the skins to the ribs and the baffle.  This worked out pretty nice as the bench had it at a good working height.

The next step we need to do is machine countersink the rivet holes that attach the skin to the baffle.  We do this so that we can easily and cleanly slide the baffle into place with it gooped up with Pro-seal. Dimpling would make this a much harder process.  I fired up the micro-stop countersink and confirmed the depth.  Per the instructions, I left the baffle clecod on to serve as a stable pilot hole for the countersink.   This took some time as there are a bunch of holes!! My countersink got pretty warm during this process, so I had to give it (and my hands!) a few breaks in between.

After countersinking the baffle row, I removed the baffle, as I needed to shift some ribs and flanges a tiny bit to backdrill the last few holes.  I didn’t snap any pics of this process, but I simply had to work the ribs around with my hands till the holes lined up and then ream them to size.  After that, the plans has us drill the W-423 screw holes as well as all the spar attachement screw holes up to a #19 size.  I got this done on the right tank.  After that, we mark all the parts so we can get them back in their places on assembly, and then disassemble the tank for deburring, and edge finishing.  Heres my right tank, and all its parts on the shelf waiting for this finish work:

That completed the layup for the right tank, and I had a little more steam left in me, so I started on the left tank.  I followed the same process as above, but I didn’t quite get to the match drilling portion yet.  I was able to get the left wing skin clecoed onto the baffle and ribs, the W-423 holes back drilled, and then the tank removed and on my bench waiting on the match drilling and countersinking to start. That was a good stopping point for the night, and a good place to pick back up on the next session.  Heres a photo of me with my wings to prove I’m the guy building it 🙂

Here’s a link to the Google Photos album for tonights work:  https://photos.app.goo.gl/gnJS9QctFQNqoJAr7
And heres all the photos for tonight:

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    IMG_0564

Hours worked: 6.25

Making the Tank Stiffeners

Tammy and Acacia went on a “Girls Night” with my mom and sister to Knoxville, and they’ll be gone overnight, which freed me up to do some work on the RV-7 tonight.  The work for tonight started with making the tank stiffeners from the provided punched and notched stock.  These are the T-711 A through D stiffeners for each tank.  They were pretty easy to cut from the stock using a pair of snips and going along the notches to indicate where to cut.  This is similar to the stiffeners used in the control surfaces, so its very familiar work.

And here’s the pile of stiffeners, cut out and ready to take to the bench grinder for deburring:

I spent about 20 minutes or so on the bench grinder working these stiffeners on the scotchbrite wheel to deburr the edges and smooth out the cuts I made. They came out looking pretty nicely.  Since these are going inside the tank, they will NOT get any sort of primer or alodine.  I will clean them with acetone before I bond them with proseal and rivet though.  Next the plans tell us to cleco the stiffeners to the tanks, and match the drill the holes.  All of these are different sizes (A through D) but Vans offsets the rivet holes making it a simple task to find the right ones and get them in the right spots.

After I had those all match drilled, the next thing was to put the T-701 tank skins onto the baffle and check the fit on the wings. I did this a little differently, as I wanted to make sure I had all my holes lined up on my baffles.  I clecod the baffle to the T-701 skins and then mounted the assembly onto the wing checking alignment.  I then clecod the skin assembly to the main spar to make sure it was steady.

Then I reached in from the side, and marked the holes onto the tank attach brackets using the baffle as a guide after I made sure the centerlines from the tank attach brackets were showing in the center of the pre-punched holes in the baffles.  I marked as many holes as I could reach, and pulled the assembly off to check my alignment:

 

It’s not EXACT, but its very close! Once I was happy with the alignment, I clecoed the baffle back down to the tank attach brackets and then backdrilled into the brackets using the remaining holes in baffle as a guide.  I ONLY drilled the center hole in the brackets, leaving the other 4 holes for later, as prescribed by the plans.

Now that the baffle had enough holes to cleco it down to the attach brackets, it was time to start cleco’ing on the ribs!  Once the ribs are on, I will backdrill the ribs, baffle, and tank attach brackets together using the rib holes as guides.  I clecoed on the ribs, double checking their placement with the plans.

I was pretty spent after clecoing the ribs on, so I decided to call it a night, and do the backdrilling when I was fresh.  Of course, I did this same set of procedures on the other wing, I just simply showing photos from one wing in the blog post 🙂 . Heres all the photos from tonights work:

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    IMG_0506

Google Photos Link: https://photos.app.goo.gl/z1bQgQJa14SmSxr19

Hours Worked: 3.5

Tank Attach Brackets Part 2

WHAT? I’m actually getting something done on the RV-7?  Yep.  Thats right, I found some more time to work on the airplane tonight. This new position at work has been keeping me busy, but I think I am going to have more time to work on the airplane since I will be traveling a lot less.  I have been briefing up where I left off this past week, so I am not adding those hours into the build.  I need to get these tank attach brackets finished up so I can continue with the tanks.  So, I pulled the brackets off the wings so I can drill the nut plates and deburr them.  I marked the locations so I could get them exactly returned to where they came from, and then started on the nut plates.  I don’t have a nutplate jig, so I had to make do with my tools on hand.  I used an AN3 bolt to thread into the K1000-3 nutplates so I could line up the “ears” on the nutplates with the centerlines I had drawn on the brackets.  Then, while holding the nutplate in this position, I drilled one of the holes.  After the first hole was drilled, I stuck a cleco in to help hold it all squared up for the last hole to be back drilled.

I used some clamps to help hold the bracket on my table as I drilled. Eventually I turned this into an assembly line:

Once I had all 12 (6 on each side) of the tank attach brackets drilled for the nutplates I moved on to deburring all the holes, as well as all the corners and edges to make them nice and smooth.  On the front side of the nutplates, they are attached with AN426 flush rivets, so I needed to countersink the holes for a nice smooth fit on the side of the tank attach brackets that gets bolted to the main spar web.  I used my clamps again to hold the brackets to the table, and then fired up the micro-stop countersink and adjusted the depth so the rivets would sit nice and flush.

I again, turned this into an assembly line, by clamping several brackets to the table and doing the countersinks all in one run 🙂 Once I had all the countersink done, I decided to go ahead and Alodine these parts.  I’m not going to prime them, since a good Alodine coating will be plenty of protection.  I got my dunking tanks out and started the process. First up, cleaning them with Alumaprep 33:

Then after a quick rinse to rid then of the Alumaprep, I dunked the in the Alodine bath for about 10 minutes:

Heres a shot of me doing the work to prove I am the dude building the plane.  You might notice that I have lost a good bit of weight!  Nearly 83 pounds to date, all from eating 1800 calories per day and doing a ketogenic diet.  It feels pretty amazing, but this blog isn’t the place to discuss dieting, unless we are measuring the gain in useful load 🙂

Now that the parts are Alodined, i went ahead and riveted on the nutplates.  I clecoed one hole of the nutplate to hold it, while I used the Numatix rivet squeezer on the rivets.  This made quick easy work of them, and in not time, I had 12 tank attach brackets all ready to go!

The plans tells us to go ahead and bolt these onto the main spar web using the AN304 bolts, and a washer (the size escapes me currently, but I did find the correct size on the plans).  I am not sure why we bolt all three bolts for each bracket, as they’ll need to come off again to rivet them onto the baffle.  So, I just used two bolts per bracket and got them snugged up onto the spar web for alignment purposes in the next step,  These will be coming off in the near future when we seal up the tanks.  I’ll reinstall them with all the bolts and apply proper torque values and then some paint some torque seal on them.  Here’s how they look for now:

This was a long working session!  Even though it doesn’t look like much was done, there was a lot of work in those nutplates! From here I’ll fit the baffle and the tank skins.  Heres all the photos from tonight:

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Google Photos Link:  https://photos.app.goo.gl/ccsAmu7qk7K5dn8k6

Hours Worked: 4.75

Drilling The Tank Attach Z-Brackets

Time to drill the tank attach Z-brackets.  I swung by Ace and picked up some cheap 10-32 bolts, nuts and washers to temporarily hold the brackets to the spar for back drilling.  These will get tossed for the final assembly, they’re just used to help steady the bracket for precise drilling.  I actually had my little helper Acacia tonight for a little while.  We stuck a bolt, and washer in each bracket and then put them on the spars.

Then I squared up the brackets to the spare to make sure they were perfectly aligned.  My little helper gave up and got bored so she went back upstairs to play with her dolls.  But I managed fine on my own. HAH.  I used the cheap nuts and bolts in the center hole to tightly hold the bracket to the spar so they wouldn’t move when I was back drilling them form the other side of the spar.

I used a small square to make sure the brackets were lined up perfectly perpendicular with the spar.

Once I had all of the brackets installed and squared, I tightened the bolts down and then double checked them with my square to be sure they didn’t move.  I did the same to both spars.  Next up was to back drill the other two holes in the brackets by using the pre-punched holes in the spars as a guide.  Unfortunately, I didn’t snap a pic of the back drilling process, nor the final results.  I’ll get a photo of them in the next build log.

I wanted to make sure I had things correct before moving on to the next step, so I slipped the baffle onto the right tank skin and then placed the assembly onto the wing so I could check that the prepunched holes in the baffler were lining up with the centers of my tank attach brackets.  Heres the baffle installed on the skin, in my jig.

And here’s the assembly cleco’d onto the wing.  The alignment was really good, and the prepunched holes were lining up nicely on the center of the tank attach brackets.  Its starting to look like a real wing now!  Now, you can see the bulging in the skin where the fuel filler is.  That is because I do not have the internal ribs installed.  This was merely a test fit to see if the baffles lined up on the center of the tank attack brackets.   The tanks will come off before I do any more drilling 🙂

I was pretty happy with the results so far, and decided to call it a night.  I’ll take the tank assembly off in the next build log, remove the attach brackets and drill their nut plate holes.  Once I have all the nut plate holes drilled, I will probably prime them, and then install them onto the spar for the next steps.

Heres the Google Photos album: https://photos.app.goo.gl/8tAeECZ8mQ5VSsi36

And heres all the photos from the build session:

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    IMG_20190915_183913

 

Total Time spent: 2.75 hours