Inboard Tank Attach Bracket

June 6, 2011

Prev | Next

Well, my order came in from Van’s today. Here are the goods.

It's like Christmas, but in June.

First up, a W-408-1R, NOTCHED NOSE RIB. Turns out, I ruined the other one by not making sure it was all lined up prior to drilling. I have a good idea on how to make this one work out, so stay tuned.

Also included in this order, my flop tubes, and some snap bushings, which I needed to order due to all of the holes I drilled in the wing ribs. (Oh man, now I want a steak.)

Leading edge rib, flop tubes, and snap bushings.

Then, the proseal (black death!), fuel tank leak test kit, and 25′ of black corrugated tubing that should fit nicely in the holes I drilled in the ribs (see steaky link above).

Black tubing, proseal, and test kit.

Even though I REALLY WANTED to break out the proseal and start slathering it all over my workbench, airplane, hands, clothes, and face, I decided to wait until my popsicle sticks and syringes come in from amazon.

So tonight, I decided to work on the right inboard attach bracket.

After studying the plans, I grabbed the AA6…I’m not going to type out the part number. See the picture below.

Yup. That's it.

(Insert silence here where I tried for 10 minutes to figure out what R1 is.)

I’m really sorry to admit this, but I started scouring the internet. Googled “VAF R1 TANK ATTACH BRACKET” and “R1 NOTE DWG 16A VANS RV-7.”

To no avail.

Then, someone’s build site (can’t remember who), admitted that they spent 10 minutes and some google searches trying to find out what the R1 stood for before they realized that it wasn’t a note, it was RADIUS=1 inch.


Okay, I’ve got some lines drawn.

Whose cute toes are those?

I think that is T-410 on the top of the picture. I used that to trace mirror images on the 2" side.

Then, I pulled a can of OFF from the shelf and used it to make a 1" radius circle. Then, connected the tangents after drawing a 1/2" line along each side of the bottom. (The drawing is half scale, and it was 1.4" on the drawing.)

After some sawing, I for some reason lost interest and broke out some of the snap bushings.

Two of the smaller size (SB375-4), and one of the bigger size (SB437-4).

Sweet. These will work perfectly.


Umm, who took this redundant picture?

Okay, back to sawing.

Hmm. This turned out to be annoying with the jigsaw. Maybe I need a bandsaw.


Insert about 30 minutes of deburring on the scotchbrite wheel….


So, then I put it in the nose of the inboard rib, and admired how nicely it fit. (Actually, it still needs a little trimming around the edges.)

Looks good.

Okay, I didn’t do a good job of taking pictures here, but basically, I drew a line 1 and 1/16″ back from the tip of the rib, and then drew a line parallel to the front edge, but 2 diameters of the final rivet size (1/8″) away.

Here's where I got the 1 and 1/16" from.

Then, I marked and drilled 5 of the 6 rivet holes, along with the center hole, which is the pilot hole for the 9/16″ hole that the flop tube fitting will fit through.


Here's a better picture. 5 plus the pilot drilled, and I've laid in the AN nut to see where I can put the sixth (marked) without rivet head interference.

This is me trying to figure out what size hole I’ll need for the fitting.

0.563? What fraction gives me 0.563?

Obviously 8/16″ is 0.5 and 5/8″ is 0.625. Let’s try 9 divided by 16.


Apparently I don’t have a 9/16″ bit, but I did work my way up to 1/2″ and then lay in some AN470AD4-7 rivets so I could show you my good spacing.

How's it look?

Here's the other side.

1.5 hours. Still need a 9/16″ bit, but that won’t stop me from getting into the tank stiffeners, drain flange, and filler cap soon.

I’m actually looking forward to it. Maybe this week.

Prev | Next

Matchdrilled Right Tank Ribs and Baffle

May 26, 2011

Prev | Next

Not many pictures tonight, but I did get the tank matchdrilled.

But first, I got some things ordered from Van’s today in preparation for the tank sealing process:

  • 60 x BUSHING SB375-4 Snap Bushings, 3/8 (1/4)
  • 1 x DUCT NT 5/8-25 Nylon Conduit
  • 30 x BUSHING SB437-4 Snap Bushings 7/16 (1/4)
  • 2 x IF-4/6 RV-4/6/6A/7/7A/8/8A Wing tank flop tube
  • 1 x MC-236-B2 Tank sealant with accelerator QUART KIT
  • 1 x FUEL TANK TEST KIT Fuel Tank Test Kit

Of course, once I placed the order, I remembered that I buggered up the inboardmost rib of the right leading edge and needed a new one. I need to remember to order that one, and BEG Van’s to send it in the same shipment.

I decided to go with 2 flop tubes. (Flop tubes allow the fuel pickups to flop around in the tank, and therefore sustained inverted flight.)

One school of thought is that if you have two flop tubes and they get stiff, you could increase your unusable fuel (they don’t flop good no more) in either the upright or inverted attitudes. People therefore put one flop tube in and one rigid pickup. This means you have to switch tanks to your “aerobatic” tank before doing negative-g aerobatics. (How often will I do sustained inverted flight? Probably not very much.)

Anyway, I weighed the pros and cons, and came to the conclusion that the aesthetics of not having a single tank for aerobatics, and therefore a checklist item or a special placard, outweighed the possibility that after 10 years, my tube wouldn’t flop as floppily as it did when it was young.

Every couple years, I’ll open up the tanks and verify adequate flopitude. They are only $38, so it’s probably worth replacing them every 5 years anyway.

So, now that I’ve settled on duel flopicity, let’s get back to building.

I decided while matchdirlling, it would be easiest for me to do it while it was on the spar, so up on the spar the tank went.

(Be careful though, Van’s notes to matchdrill off the spar to avoid damaging the spar. This is really only a concern with the baffle holes (about the 10 most inboard ones). Take the tank back off the spar do matchdrill those.)

No action shots today, but much cleco-moving.

Back off the spar for baffle drilling.

Next up is fuel tank stiffeners, then a lot of prep before assembly of the fuel tanks.

1 hour.

Prev | Next

Started Banging Rivets on the Right Leading Edge

April 22, 2011

Prev | Next




Well, even though my last post said I was getting back into the mood of airplane building, it’s been almost a MONTH since I spent time on the project.


Anyway, I had a day off today, and I managed to spend a couple hours in the airplane factory.

Let’s see if I remember how to take and post picture.

After a little garage cleanup, I got the right leading edge out and got back to deburring all of the holes. I think deburring took about 30 minutes.

My hand hurt after deburring all of these. I need to deburr more often.

Once done, I took the cradles off the skin and opened her up to do some scuffing.

I haven't totally finished the leading edge light installation, but I can do that after the ribs are installed.

Then, I broke out the c-frame and started dimpling. This actually takes awhile, because you have to be careful not to punch any extra holes in the skin.

Even though I can reach these dimples with my squeezer, I think you get better, crisper dimples from the c-frame.

Here's me doing the forward-most hole in the top of the leading edge skin.




Well, after 242 hours, and thousands of dimpled holes, I finally joined the club.

To tell you the truth, it’s really not that noticeable, except for the fact that it is on the top of the wing (AND YOU’LL ALL NOTICE IT)!

Anyway, I used some flat sets and pounded it flat, then filed it down a little, and dimpled the primary hole.

Here's the extra dimple pounded flat.

And the orginal hole dimpled. still needs a little filing here.

I could throw a fit and order a new leading edge from Van’s, or I could just build on, and cover this with filler and paint.

(I don’t think I can polish the wings anymore.)

Well, in the interest of building on, I decided to do a little riveting today. I had a couple ribs prepped (my legend: R2 and R3), so I got them prepped, primed, and clecoed in place. (Making sure to cleco one rib on either side of those so the leading edge was perfectly straight.

Here are the ribs clecoed in place.

Of course, I use my normal tape-over-each-rivet-head trick to minimize scratches, dings, and marring.

I shot and bucked every other one (no mistakes) and then replaced the clecoes with rivets, moved the tape over, and finished the row.

(Needless to say, I started with the bottom of the leading edge, so any mistakes due to out-of-practice riveting wouldn’t be so obvious.)

Gratuitous shop head shot on the lower surface of the first rib.

Gratuitous shop head shot on the lower surface of the second rib.

Wash. Rinse. Repeat. (Crap, I meant flip, cleco, rivet, repeat.)

Gratuitous shop head shot on the upper surface of the first rib.

Gratuitous shop head shot on the upper surface of the second rib.

Umm, did we not have enough shop head shots today?


Here’s the “club” rivet. I think I’m going to leave it like this, and just watch it for cracks, but someone will probably tell me I need to drill this out and replace it with some other solution. We’ll see.

(big. depressed. sigh.)

Seriously, I need to control myself with this camera.

Oh, and I was having trouble counting rivets today, which was weird.

So I just started writing them down. Can you guys check my math?

3 hours, 58 rivets, 1 figure-8. Boo.

Prev | Next

50% Clecoed Right Wing Skins

February 7, 2011

Prev | Next

Well, my order of clecos showed up. It was in a pretty small box on the front step, but that little tiny box was deceptively heavy.

After unpacking the box, I noticed that this bag is a bag of 500 clecos.

They actually opened the bag and removed 100 clecos to get to my order of 400. I wish I had known, I would have ordered another 100 just to save them the trouble of counting them all out.

Bag o' clecos!

Anyway, I emptied them into my (now empty) silver cleco bin (an old tupperware container).

I even left the automatic flash on so they would shine a little extra for you.

These things are brand-spanking new. And made in the USA.


Some people on the forums were pointinng out that I got a heck of a good deal at $0.35 each, and they suspected they were not going to be the new, USA-made clecos.

Well, these are new.

This next picture shows a few of my different kinds of clecos. From left to right:

1) Clekolok USA, new today (from Innovative Tool Supply)
2) Kwik lok USA, purchased about a year ago (from the Yard)
3) Kwik lok USA, purchased about a year ago (from the Yard’s used bulk area)
4) Unknown, purchased about a year ago (from the Yard’s used bulk area)

New to old, they all work the same. I haven't noticed any degradation of holding power.

Anyway, I then spent the next half hour sticking these new clecos into my right wing.

Based on a conversation with Bill Repucci, I’ve decided to mitigate all of my alignment concerns by just 50% clecoing the wing. (50% meaning every other hole, as opposed to 25%, which would be the Van’s suggested everth fourth hole.)

I have to admit, that thing is rock solid now.

The right top skins with a cleco in every other hole.

I looked at my new cleco stash and realized I was about halfway through them already.

Crap... those went fast.

After another half hour of every other hole clecoing the right bottom skins, I reached in my cleco bucket and only had two clecoes left.

Uh oh.


I almost made it with 600 clecos.

There are a few missing clecos along the rear spar (towards the bottom of the picture).

When I get to that area during matchdrilling. I’ll just move some of my clecos from other areas.

1 hour of clecoing fun.

Contrary to what other builders have to say, my hand isn’t that tired, and I therefore don’t intend on spending $200 for a pneumatic cleco runner. Take that!
Prev | Next

Riveted the Right Rear Spar to the Main Ribs

January 23, 2011

Prev | Next

Well, today was a crappy day. I had mucho problems with riveting the right rear spar to the main ribs.

I’ll walk you through what happened.

I started with the inboard side of the spar. The plans call for an AN470AD4-8 rivet. As you can see below, this is a little for a good shop head.


Here's an ...AD4-9 rivet. This looks better.

After some gymnastics with my good squeezer, which only has a 4″ no-hole yoke on it, I realized that I needed the holed yoke, and therefore needed to use my economy squeezer. Bummer.

(Back in the empennage, I stopped squeezing AD4 rivets altogether because I kept messing them up; the economy squeezer just didn’t have enough oompf.)

Anyway, I managed the wingwalk rivets with the smaller squeezer. Here’s 9 rivets squeezed.

I couldn't reach the top-most rivet in 3 of the 4 wingwalk ribs. (The other open hole in each of the rib attach points needs to wait for the flap brace.)

I moved my way outboard from there, two rivets in each rib.

Halfway there, I bent over both of the rivets in the aileron pushtube doubler area, and drilled both of those rivets out. Then, the aileron gap seal switches “open” rivets (compared to the flap brace) so of course I set a two rivets there that had to be drilled out.

When I got to the end, I noticed things weren’t lining up very well.

Duh. Forgot to dimple the aft side of the outboard rib.

That's better.

I still couldn’t reach the one rivet (shown on the left here), but I got the other 3 set properly.

The apparent gap between the two flanges isn't really a gap, its just the shadow.

Let me bring you back to the very first rivet I set. The camera is upside down here (so the part is right side up).

The upper, leftmost rivet bent over (it was the first one I set with the economy squeezer). After drilling out, the hole was englarged.

With only slightly enlarged holes, sometimes you can just squeeze another rivet (a little longer this time) and it will expand to fill the hole nicely.

This is after setting another rivet.

This one did not properly expand, and by the time the shop head was formed, it kind of formed in the hole.

Hmm. I know this is a critical piece, so I’m going to have to call Van’s and ask them what the best course of action here is.

I’m hoping I can step up to a AN470AD5-9 rivets, but I’ll need to drill the rivet and hole out to 5/32″ and I’m worried about edge-distance in the up direction.

We’ll see what the guys at Van’s have to say.

January 31st update: Ken S at Van’s wrote back.

A 5 rivet should work ok. If you can fill the hole with the original rivet, that’s ok too –even with
a slightly undersize head. Just be sure that the rivet engages the entire circumference of the

Alright. I’ll have to add AN470AD5- rivets to my next order from Van’s or Aircraft Spruce. In the meantime, I’m going to keep working on other stuff.

U-G-L-Y, you don't have no alibi, you ugly! {clap, clap} You ugly!

1.5 hours and 28 stupid rivets set (my arms are tired from the economy squeezer); 8 of those drilled out.

I’m going to have to buy a new yoke ($$$) and probably do some surgery on the offending rivet in the last picture.

I’m stopping this post and starting another one (click next below) because I moved on to the skins. I really needed to end on a good note today, and the skins actually did the trick.

Prev | Next

Left Spar Arrived from Vans

September 21, 2010

Prev | Next

I was home at lunch today randomly (so I could pick up more propane for tonight’s planned grilling session), when I passed a FedEx Express van.

Hmm. That’s weird. Last Thursday, I got an email from Jessica at Van’s saying they had shipped my left spar back to me via FedEx Express, and it was supposed to arrive tomorrow.

Using some critical thinking skills (and the realization that I had NOT been diligently tracking my package over the weekend), I figured the FedEx Van was in the neighborhood for me. I flipped around and followed the driver back to the house. (It’s amazing how incrementally excited I got after each turn back toward the house.)

Anyway, the spar arrived, and it was, in fact, a new, undamaged spar.

Came in its own cute little crate.

No damage!

I didn’t post a lot about my left spar before, because I wanted to see how it would end up before posting to the world, but here’s a quick summary. My left spar, as received in the wing kit, had a pretty small dent in the lower inboard flange. While it was probably airworthy, I was concerned that I didn’t know how much margin on top of limit load I had lost (if any). Also, would there be any residual stress in the area of the deformation, and what long-term stress cracks should I anticipate based on this dent? Do I have to disclose this damage if I ever sell the airplane?

(Background: The airplane is designed for +9/-6 Gs, and the limits placed on the airplane are +6/-3 Gs. The idea is that a spar with damage might really only be good for 8.8 Gs now, or maybe 8.5 Gs (or, admittedly, 8.999 Gs…it was a really small dent).

(Philosophical question: If you could quantify the new margin, and a spar was good to a known 8.5g instead of 9g, and you were still limited operationally to 6g, would you accept it? I still don’t know the answer to this. I think an 8.5g spar would meet the design intent of the airplane (but Andrew! what about 8.4g?!), but what if I accidentally over-g the airplane, something breaks, and I am falling helplessly to the ground. With a “perfect” spar, at least I know it was all my fault. With a dented spar, I’d be cursing Van’s the whole way down.)

(Dear Mom. There is no way I’ll ever over-g the airplane. Stop worrying. It was just for discussion purposes.)

If we could quantify what I’ve lost if I continue to build with the damaged spar, I may be okay to proceed with enough residual margin, but I have a hard time putting a spar in my airplane knowing it isn’t perfect structurally and not being able to quantify what I’ve lost. For the record, I’m an engineer… this has nothing to do with the small scratches and scotchbriting everyone has on their spars. I’m talking about material deformation.

Anyway, Gus and I talked (about loads…bending, drag, torsional, etc., but I’ll leave that out of here for now), and they really don’t have the capability to do an analysis on a spar flange like that, so he agreed to send me a replacement spar if I could send the other one back. (They can do an ultimate load test on a completed wing, just for future trivia.) Luckily, since this was shipping damage, ABF has picked up the shipping tab. (ABF customer service was less than optimal).

I feel a little guilty about standing ground about the damaged spar, but I think some of that has to do with work (if a spar had come into work like that, we would have either immediately rejected the part and sent it back, or performed enough engineering analysis to deem it acceptable as-is or with a repair). I want to be able to take my airplane to +6/-3 Gs and not always question whether my margin is the same as everyone else’s.

(I’ll leave out the more philosophical discussion about whether the margins on top of the posted limits are equal given the widely-ranging construction practices and skills that appear to be out there in the build community. I have to assume the airplane is designed to fly with plenty of margin after being built by a below-average builder, but can still pass Tech Counselor and DAR/FAA inspections.)

Ultimately, Van’s did a great job managing my concerns and communicating quickly and effectively about the whole problem. I really do appreciate their commitment to customer service, and their willingness to listen to my engineering concerns about the defect.

Thank you, Van’s.


Back to building!

Prev | Next


June 22, 2010

Prev | Next

After getting stung by a wasp two times in the last two days trying to mow the lawn in the backyard, I gave up (shows determination and perseverance, huh?) and retreated to the comfort of my garage for some airplane work (the floors can wait until tomorrow).

Back to the tab. Before I do any more cutting on the elevator, I want to get the tab hinge drilled so I know exactly where the outboard edge of the tab will swing. I am doing this before they really tell you to in the directions (the directions have you actually finish the elevator, then start working on the tab.

Anyway, you are supposed to draw a line 1/4″ from the loop edge of the tab, and first matchdrill that to the tab. (I started with the elevator side, which eventually bit me in the ass. Read on.)

I decided to mark both sides with the 1/4" line. Hmm. Doesn't look like there is going to be a lot of edge distance.

Then, I took the hinge apart (you can see the hinge pin in the next photo) and clamped the elevator side to the elevator, lining up my 1/4″ line in the first prepunched hole, and aligning the first hinge loop where I thought it looked good (making sure this fit with the plans).

Hint: If you take apart the hinge, you can easily clamp the hinge half to the elevator (and tab, with the other half).

Next, I lined up the outboard side. This tab hinge is nice and square with the edge, and with the holes.

Let’s drill!

Here are 6 holes drilled (I'm working inboard to outboard).

All done with the elevator side.

Next, I reassembled the hinge and spent a few minutes just kind of getting everything lined up.

I wish this were the final product, but this is just me mocking things up before drilling.

With the greatest of coordination, I managed to hold a straight-edge against the inboard edge, line up the inboard pre-punched hole with the 1/4″ line, and line up the trailing edge of the tab with the trailing edge of the elevator, AND take this picture. Boo-ya.

Looks good so far.

Then, I drilled the inboard hole. The inboard side is perfect. (Can you tell that some other part may not be by the way I phrased that?)

If you look closely (lower left corner), you can see that the tab trailing edge is further aft than the elevator trailing edge.

I was pissed. I lined up the hinge with the elevator edges and holes, and with the tab edges and holes. This means that either the elevator or the tab isn’t perfectly square.

I thought about just moving the tab forward, but then there would be slightly different distances between the skins from inboard to outboard. I measured it…it would have been about 1/32 difference. No one would have noticed except for me.

But…I can’t leave it alone. I’m going to reorder the hinge and try again. This time, I’m still not going to follow the directions. If you make the hinge perfectly square to the tab, it’s going to be off on the elevator side. I’m going to have to split the difference between both by first clamping the tab in perfect position, then clamping the hinge in place and matchdrilling a few holes.

Admittedly, I should have followed the directions by starting with the tab edge, but it wouldn’t have mattered, it still wouldn’t have been a perfectly square hinge line after I was done.

The tab hinge is AN257-P2 according to the materials list in Section 4, but the part shows MS20257-2.

I also think, given my edge distance worries (must be okay because it is per the plans? I don’t know), I am going to order the MS20257-3 (or AN257-P3, which is 1 + 1/4″ wide instead of 1 + 1/16″). I checked with Van’s, and they want $9.70 (plus $4 handling, plus $12 shipping or something) for an 24″ piece of AN257-P3.

I checked aircraft spruce, and they wanted $4.75 for a 3′ piece and $1.73 shipping via USPS.

Which one do I choose?

Duh. $6.48 for my first re-ordered part. Bummer. (It’s better than a $60 elevator skin, though!)

Here are my edge distances.

I love this kind of building. Thinking, playing, mocking up, etc. The normal matdrilling dance gets old…this is the stuff I really like.

1.0 hour tonight. Frustrating, but fun.

Prev | Next