Started Riveting Bottom Wing Skins (1/20/11)

4.0 Hours –

It’s been a couple of days since I’ve worked on the plane, so I was happy to have the day off work with little to do other than spend time in the garage.

To start the work session, I applied some blue RTV to each of the ribs/conduit.  Van’s recommends using either RTV or tank sealant, so I opted for the RTV just to avoid tank sealant whenever possible.  The purpose of the RTV is to prevent the conduit from moving or vibrating too much.  I applied sealant on both sides of each rib, but only on the aft side of the conduit.

I placed some blue RTV on both sides of each rib to prevent the conduit from moving.

Next, I put the inboard bottom skins back on the wings and worked on a plan for how to rivet them. I’ve opted to keep the wings in the cradle while working on the bottom skins.  Between my long arms and some gentle bending of the skins, I decided I could make it work.  Eventually, I broke out the rivet gun and went to town on the left wing.  I followed the plans as closely as I could (they’re not very clear here), and started by riveting the skin to the aft spar in the wing walk area.  This was a little tricky/awkward because it was a long reach up to the aft spar, and even more of a challenge to place the bucking bar blindly.  Once this section was riveted to the aft spar, I started working my way down the wing walk ribs.  The closer I got to the forward spar, the easier this became.  Once I finished the entire length of these ribs, I went back to work on the aft spar and riveted to the next rib.  At this point, I’d been working for four hours and decided to call it a day.

A couple of dings, but overall, the first half of the inboard bottom skin looks good.

Tomorrow, I’ll be heading back to the Burnet, TX, to do a little more tailwheel flying in a Super Cub.  If all goes well, I’ll have my tailwheel endorsement by the time I return to San Antonio on Saturday!

Bottom Inboard Skin Prep (1/17/11)

3.5 Hours –

Today, I finished prepping the bottom inboard skins for both wings.

I picked-up where I left off on the left skin and finished dimpling.  Once this was done, I scuffed, cleaned and primed the inside surface of the skin. 

An action shot of some dimpling.

As the primer dried on the left skin, I returned to my ongoing task of pulling wiring conduit through the right wing.  I don’t know what it was, but for some reason I was able to pull the conduit much faster today.  After 15 minutes, I had the conduit completely pulled through the 4 ribs of the wing walk area.  Once the wing walk area was done, the rest of the wing was easy.

It took me two weeks, but the conduit is now completely installed in the right wing.

After the primer was dry on the left bottom inboard skin, I temporarily mounted it to the wing with a few clecoes (mainly to get it out-of-the-way).  Then, I turned my attention to the same skin for the right wing and started the whole process over…deburr, dimple, scuff, clean, prime.

More priming...this is the inside of the bottom inboard skin.

Once primer was on the right skin, I turned my attention to the pitot/AOA tube.  The pitot/AOA tube is the only other thing that I need to install inside the wing before buttoning it up.  It could be installed after the skins are riveted, but it is easier now.  The first decision to make is where to install it.  If I follow the instruction from Safeair, it will be installed on the outboard side of the first rib outboard of the bellcrank.  Since the bellcrank and the tie-down ring are at the same position, some RVers have found this location to be problematic as tie-down ropes may interfere with the pitot tube (the stubby wings of an RV often cause tie-down ropes to point towards the cockpit instead of away).  To prevent this interference, some builders have moved the pitot tube inboard of the bellcrank.  I need to do some research to see how far inboard people have moved it.  From what I can tell, screw for the fuel tank will interfere with more inboard mounting unless I modify the pitot mast somewhat.  In the meantime, I went ahead and installed all of the snap bushings in the wing ribs for the pitot and AOA lines.

A possible location for the pitot tube is in the bay outboard of the bellcrank in the left wing.

I installed the snap bushings for the pitot/AOA lines. However, I'm not sure where the pitot tube will be, so some of these may come out.

Started Bottom Skin Prep (1/16/11)

1.8 Hours –

I was hoping that the time between riveting the top skins and preparing to rivet the bottom skins would be a little longer, but the time has come.  Today, I started the final prep of the bottom skins.

Since the inboard skins go on first, I started by removing vinyl strips from those skins.  As with the top skins, I’m removing vinyl along the rivet lines only.  I’ll prime the rivet lines on the inside of the skin, then remove all of the vinyl from that side before riveting.

A picture of me removing blue vinyl from the bottom skins...I feel like I've done this before!

After “de-bluing” both bottom inboard skins, I deburred the left skin (edges and holes).  Then, I hand countersunk the nutplate attach holes around the access holes for some “oops” rivets.  Although I’m prepping the access areas now, I won’t attach the nutplates until after the skins are on the wings.  If the nutplates were put in place now, I’m afraid they would wreak havoc on my arms as I reach into the wing to buck rivets.  Access for riveting the nutplates later will be easy anyways. 

Finally, I set up my squeezer with a #40 dimple die set and started to dimple any holes in the skin that the squeezer could reach.  I made it through most of the squeezable holes in this skin before deciding to call it a night.

I started dimpling the left inboard skin and then called it a day.

Riveted Flap Braces and Aileron Gap Seals (1/15/11)

3.0 Hours –

In the morning, I set up a 2″ Scotchbrite wheel in my die grinder and used that to deburr the lightening holes in the flap braces.  There are quite a few holes in each part, but deburring went fairly quickly.

Once the flap braces were deburred, I scuffed, cleaned and primed both the flap braces and the aileron gap seals.

Yes, yet another priming picture. I definitely prefer the NAPA 7220 self-etching primer over Duplicolor.

Later in the day, I returned to the garage and riveted the flap braces and aileron gap seals to the wings.  The flap braces went on first and I had to buck/shoot all of the rivets attaching the flap braces to the aft spars.  fortunately, they were all set well with no drill-outs or other problems.

The flap braces are riveted to the aft spar. The other side will be riveted to the bottom skin and flap hinge.

After the flap braces were on, I riveted the aileron gap seals to the wings.  The gap seals were riveted to the aft spar first.  Most of these rivets could be squeezed, but the rivets that attached the gap seal to both the aft spar and a rib had to be bucked due to the rib making access with squeezer challenging.  After the rivets in the aft spar were set, I squeezed the rivets that attach the gap seal to the top skins.  Once again, I lucked out and had no bad rivets on the gap seals!

The inboard portion of the aileron gap seal after it has been riveted to both the aft spar and the top skin.

The outboard end of the aileron gap seal.

The next step in plans is to rivet the bottom skins to the wings.  However, I’m wondering if I should delay this until last and build/fit the ailerons and flaps first.

With the flap braces and aileron gap seals riveted, its time to work on the bottom skins.

Countersunk Flap Braces (1/14/11)

0.8 Hours –

The title says it all…today I countersunk the holes on the bottom of the flap braces where the bottom skins will attach.  The corresponding holes in the bottom skin will be dimpled.

I also deburred the edges of the flap braces, but I still need to deburr all of the lightening holes.  A small Scotchbrite wheel in my die grinder should make quick work of these.

The flap braces are countersunk on the skin side.

Deburring, a Little Dimpling and Some Countersinking (1/13/11)

1.0 Hours –

A local RV-9 builder came over this evening and picked up my wing stands.  I’m happy that someone else will be able to use them, but I’m even happier to have freed up 16 sq. ft. of floor space in the garage!

As for work on the plane, I continued prepping the flap braces and aileron gap seals.  I deburred the edges of the aileron gap seals using my Scotchbrite wheel and some strips of emery cloth.  While working on the Scotchbrite wheel, a couple of large strips on Scotchbrite came flying off.  At the price of these wheels, it’s almost painful to see that much fly off, but at least there is plenty left.

These two chunks came off my Scotchbrite wheel while I was deburring the aileron gap seals.

You can see where the chunks came off. Good thing there is still a lot of Scotchbrite left!

Once the edges were deburred, I dimpled the #40 holes that attach the gap seals to the skins.  I also dimpled the corresponding holes in the top wing skins.

Next, I started working on the flap braces again.  The flap braces attach to the aft spar and to the bottom, inboard wing skin.  The flap hinge also attaches at the same flap brace/skin holes.  Because of this, the bottom skin gets dimpled, the flap brace gets countersunk, and the flap hinge is only drilled.  If you don’t think about this ahead of time, you’ll end up dimpling the flap brace and then having to fix it by flattening the dimples and countersinking or by dimpling the flap hinge.  I probably would have missed this as well, but I happened to have read about this problem on a couple other builders’ websites.

Since the flap brace material is thin, I knew that I needed something to guide the countersink pilot.  With this in mind, I drilled and clecoed the flap brace to a piece of scrap 2″ x 4″.  The holes in the wood will serve as guides for the countersink cutter.  I setup my electric drill with a #40 countersink cutter and made one countersink in the flap brace.  Using a rivet, I check that the countersink was the proper depth and then decided to call it a night…it’s cold in the garage!

I drilled and clecoed the flap brace to a 2" x 4". The wood will serve as a guide for the countersink cutter.

Gotta love it when a plan works.

Flap Brace and Aileron Gap Seal Deburring (1/12/11)

0.9 Hours –

Once again, no pictures from this work session.  Who wants to see pictures of deburred holes anyway?  That’s all I did this even…deburr holes for the aileron gap seals and the flap braces.  I deburred both the parts themselves, as well as the corresponding holes in the wing aft spars and top skins.  The edges of the parts still need deburring, but then it will be time to dimple/countersink, prime and install.

Flap Brace and Aileron Gap Seal Work (1/11/11)

1.5 Hours –

Nothing too exciting in this work session.  However, it did last about twice as long as I planned.

I finished drilling the aileron gap seals and flap braces to the skins.  To do this, I had to partially reinstall the bottom skins, which took some time to install and remove.

Since I had broken down my skin crate when I made the wing cradle, I had the skins (and a few other parts) just sitting on my workbench.  For longer term storage, I decided to build a little shelf in the cradle between my wings.  Nothing fancy, just a couple lengths of  2” x 4” nailed to the top of the cradle about half an inch apart.  The skins slide vertically between these and also rest against the vertical angled support of the cradle.  If nothing else, it keeps the skins out of the way, yet easily accessible.

Once I had everything drilled, I removed the bottom skins, as well as the flap braces and aileron gap seals.  With these off, I could access a rivet in the left inboard aileron bracket that wasn’t set well and was bothering me.  When drilling out the rivet, I slightly enlarged the hole, so I replaced it with a 5- rivet.  After this rivet was set, I also installed 4 other rivets (two in each wing) through the aft spar, reinforcement and rib, that I originally left open because I thought they were used for the flap braces.  However, after I test fit the flap braces (and double checked the plans) I realized that these rivets could have been set previously.  Oh well, a few hits from the rivet gun and they were in.

Flap Braces and Aileron Gap Seals Drilled (1/10/11)

0.7 Hours –

Nothing too exciting on the plane this evening.

I clecoed the aileron gap seals (W-724 L&R) to the wings, then final drilled (#30) the gap seals and flap braces to the aft spar.  The gap seal to skin and flap brace to skin holes will have to wait for another evening since I’ll need to reinstall the bottom inboard skin in order to drill the skin attach holes in the flap braces.

The right aileron gap seal test fit to the wing.

Inboard end of left aileron gap seal. I need to drill out and replace the aileron bracket rivet on the bottom right of the picture.

I also finished pulling conduit in the left wing.  By starting in the middle and working out to both ends, it was much easier to install the conduit.  On the right wing, I still have about a quarter of the conduit to pull through.

I finally managed to get the conduit pulled through the left wing...still have a ways to go on the right!

Wings In Cradle, Aileron Brackets, and More (1/9/11)

2.7 Hours –

After lunch, I recruited my girlfriend, Amber, to help me move the wings from the stands to the cradle.  I removed all of the clamps, bolts, etc, that held the left wing to it’s stand.  Then, I moved the cradle closer to the wing and had Amber position herself on the outboard end.  We lifted the wing off the stand, took a step towards the cradle, flipped the wing over, and gently lowered it into the cradle.  The cradle fit the left wing perfectly!  Could I be so lucky for the right wing?

With the left wing in the cradle, I moved the stands out of the way and nudged the cradle closer to the right wing.  The right wing was a bit more awkward because we had to lift it over the stands.  However, we got it into the cradle, and the fit was, once again, as good as I could have hoped for!

Next, I placed two 3/8” bolts through the wing/fuselage attach holes at the inboard end of each main spar.  Before inserting the bolts, I wrapped their threads with some duct tape so that the threads didn’t damage the spar.  The bolts will prevent the inboard end of the spar from sliding off the cradle.  I had seen this trick on several build sites, so I’m not sure who to give credit to.

Now that both wings were in the cradle, I was able to rearrange the garage a bit.  Wow, so much more room with the wing in a rolling cradle and the original stands tucked into a corner!

With my girlfriend's help, we wrangled the wings into the cradle and they fit perfectly!

The inboard end of the wings/cradle.

The outboard end of the wings/cradle.

I placed duct tape over the threads of some 3/8 bolts and slid two of them through each spar to block the wings from sliding off the cradle.

Back to construction…

Since I had previously assembled the aileron brackets, all I had to do was final/match drill them to the aft spar and rivet them on.  It sounds simple, but it took a lot of time.  Three of the four brackets didn’t fit well and needed modification.  The top edge of the brackets didn’t fit the curve of the aft spar, causing the brackets to not sit flush on the spar.  To fix this, I used my Scotchbrite wheel to taper the upper sides of the brackets.  Curving the edge of the brackets was all it took to get them to fit the aft spar correctly.  Now I could cleco them in place and drill all of the holes.

After deburring all of the holes, I started to rivet.  I was hoping my squeezer would work on these, but it seems to struggle with longer 4- rivets.  So, I set up my rivet gun and started shooting.  I had a couple rivets bend over on me, so there was some drilling out and re-riveting that had to be done, but, overall, this riveting session went well. 

Each bracket has one rivet that is a flush rivet, so pay careful attention to the plans.  For some reason, my squeezer didn’t have any problem with these, so I was able to quickly set the four flush rivets.

An inboard aileron bracket. The bottom outboard rivet is flush.

Another view of an inboard aileron bracket. Note the single flush rivet.

An outboard aileron bracket. The inboard bottom rivet is flush on this one.

The outboard side of the outboard aileron bracket.

Finally, I pulled out the flap braces (W-721 L & R) and started work on those.  The braces have a small section that needs to be removed from the inboard end.  As usual, Van’s put a couple of notches in the pieces for use as cut guides.  Connect the notches with a line and cut on the line…simple.

The flap braces have a small section that has to be tapered. As usual, Van's provides some notches as a cutting guide.

Once I cut the flap braces, I clamped them to the wings for a test fit.  Looks good and I’m calling it a night!

Test fitting the flap braces.

The inboard end of one of the flap braces.