Riveting on Right Bottom Skins Started

I seated all the rivets for the bottom skins this evening and while I was doing this on the outboard skin I realized I had forgotten to drill the hole for the tie down ring. There was no good way to do this without taking the skin off as I would have drilled into the tie down threading. Oh well, I had to remove the rivets I had seated and remove all the clecos and just move the skin over a bit to get clearance for drilling and then I could safely widen the hole to 3/8". No problem but half an hour lost to this.


Riveting was fun as always but I couldn't do more than half of the rivets along the main spar and on the nose ribs. I also removed the clecos to open the holes to receive the next set of rivets. For now I leave them open though to not interfere with the air hose while I'm riveting the rear of the wing.
I probably do some more work on that tomorrow evening. It is supposed to get a bit warmer the next few days, so that'll help.

Finish Kit Ordered

Although I still have a fuselage kit sitting in a box untouched I thought it to be wise to get the order for the finish kit out before the end of the year to avoid some nasty increase in price along with the new year - only to order the finish kit anyway a few weeks into the new year. I guess I have room to store another box on the patio and the one that contained the wing parts is soon to be gone.
So I faxed out the order this morning. Another $9k practically gone :-(

Considering Paint Scheme

Getting closer to the fuselage I have to come up with some decisions about the paint scheme. At least I want to as I'd like to have an interior that looks good with the outside color in the area around the cockpit.
I am sure about the colors I'd like to use but the distribution is very uncertain. Everything I could think of so far appears to be a paint job for a pro if you want it to look good too. That was until I had an epiphany last night.
Inspired by some fancy paint schemes developed for WWI biplanes, I came up with this:


It should be fairly easy to paint and it would allow for an early start by painting the empennage first and get some experience doing it. It limits the masking to the tailcone and the rest should go on quickly.
I will surely revise this a bit and maybe add some stars in the blue part if it doesn't look cheesy but so far I like the idea.
Comments are welcome!

Bottom Right Skins Clecoed On

I fabricated the two wires for the landing light (I assume constant and flashing light function have separate wires) and ran them through the wing, along with a thread and the wire for the nav light that I had already lying around from when I made the wire for the left nav light.


Before I had started the wiring task, I had touched up the priming job on the skins and let them dry in the heated shop. So when I was done with the wiring, I assumed the skins to be dry enough to put them on. As I now have enough clecos I didn't worry about doing the skinning one skin at a time but put them all three on.
By now the sun had set and boy was it getting frosty. I'm sure that Dave is going to laugh at this line as his Ohio hangar is probably colder right now even with his running "cone of comfort" heater. Anyway, for me as a Southern Arizonan 40 degrees is way too cold to be comfortable. The halogen lights helped while working close to them but my feet didn't care about that at all.
I was definitely happy when I put the last cleco in and didn't even think about starting the task of setting the rivets. No way! That's up for tomorrow or another day.


All I could pursuade myself to do after clecoing was to mark the holes that shouldn't get riveted yet. Just in case I would forget to do that at the beginning of the next session.

Right Bottom Skins Primed

What an unusual day it was today. It started out cold but very sunny. The morning was too cold to shoot any primer as the minimum temperature for the primer is 45 degrees and the thermometer didn't make it that far up. So we went for a little hike up Sabino Canyon to lose some of the weight we gained over Thanksgiving. Walking back down the canyon clouds were building up quickly and the sunny day turned into a grey November day, accompanied by some nasty gusts.
When we got back home, the cloud layer covered 80% of the sky and the gusts kept on rolling so there was no thought of spraying primer. I am aware though that it will take some time until it is getting warmer again and I am really worried that I might run of usable weather to get the skins ready before it will be constantly below 45 degrees. As today was the last day of the weekend and my only chance to prime the bottom skins before next weekend (which I wanted to use for the top skins and get it over with), I needed an idea how to prime in windy conditions.
It was then when I realized that I don't have to use the HVLP gun to prime the skins. They explicitly say that you can use any method to get the primer onto the metal with Cortec-373. You can spray it, roll it, brush it and even dip it. So, I scrounged through my painting utensils and soon found a nice synthetic short hair roller that was perfect for the job. Fortunately the skins are all flat and perfectly suited for roll application. Good choice as it turned out because just when I started rolling the primer on, it then started raining on top of the gusts. And I was snuggly covered by the house and the patio cover working on the lee side of the wind. After two hours I had put two coats on each skin and now they are stacked in my workshop with the heat turned on to dry them.

Right Bottom Skins Prepped

I finished deburring and prepping the right bottom skins using my trusted Cortec-440. Splashing with water (and subsequently getting wet) is really not that much fun end of November, even here in Tucson. Fortunately, we had quite a warm day and I could do the splashing part of the job on the Western side of the house so I had some sun shining in my face (and dried quicker).

Finished Section 15

After the cold morning had been warmed up by a sun shining from a beautiful blue sky, I set up the priming job. 12 nose ribs had to get shot and I knew with those low temperatures the drying process would take much longer than usual. Despite the wait the job was done within 2.5 hours and the ribs were put in the sun for deeper drying.


After about 2 hours of "tanning" in the sun I riveted the ribs to the wing. I also riveted the stub spar onto the nose ribs, so that the wing is practically ready for the skins - if only they were ready.



So now I'll have to get the bottom skins ready. More scrubbing and priming ahead!
But Section 15 is done. Overall time for this one was 50 hours.

Right Rear Spar Riveted

Besides finishing prepping the last 2 nose ribs I also clecoed, match drilled and riveted the rear spar of the right wing. Then I had to go back inside and help my wife with the Thanksgiving cooking. But there wasn't anything else to do before priming the nose ribs anyway. That will be the job for tomorrow.

And another 6 down!

Another 6 nose ribs that is. We got off early today and so I used the extra time and the warmer temperatures during the afternoon to scrub 6 more nose ribs with Cortec-440. 2 more to go which I will probably do right before priming.

Scrubbing Away... Again

In the cooler temperature it's not that much fun anymore to do some prep work on the ribs during the evening but it doesn't help complaining either. The work has to be done. I got 4 nose ribs done tonight and 8 more to go before I could prime them. I guess I should be able to do 4 more tomorrow and then 4 on the day when I prime before setting up gear.

Right Wing Started...

... or Back to Section 15. Whichever you like more as the title for the second chapter of todays work.
I couldn't help myself! It seems I am over this nasty stomach bug and full of energy after this week of an unwanted break. And with all that vacated space now that the left wing was moved to the cradle, I just had to get started on the right wing.
This time, knowing what I was supposed to do it went even faster. 2 hours and the main ribs were riveted to the main spar.


Not much more to say, I guess. I can see how I will be held up by those not yet primed nose ribs though. Oh well, Thanksgiving Weekend is coming up ;-).

Left Wing in Cradle

Today I moved the left wing to the cradle with the help of my wife Elizabeth. I had to cut out the section of the carpet that would press on the stall warning tab as the cradle was covered with carpet over its full length.
No problem getting it in and somewhat balanced with the CG in between the coasters. Now I'm ready to get started on the right wing!


It is getting a little crowded on that patio now!

Nav Light Ready for Final Installation

Installing the wiring was pretty simple and quickly done. This stomach bug is still wearing me out and so it took me much longer than it should have. First I had to learn how to crimp Molex connectors as there wasn't anything in section 5. Taking a closer look at the AeroLEDs installation manual that came with the nav lights hinted to a PDF file on their website. The direct link to it is here.
The crimping tool they recommend is not necessary. The company they refer to sell it from is out of business since July 2010 anyway, so just get a similar crimping tool at HF. The A and B positions work with that one too. I wanted to give you the HF number but it appears they haven't listed it on their website - at least not under 'crimping'. I'll make a photo next time I'm in the shop.
After installing the wiring and testing the light, it was time for final installation when I stalled. The reason is that they want you to seal the nav light fairing where it contacts the wingtip with Pro-Seal. When you mix Pro-Seal you have to use it up or it will cure and you lose the unused rest. Well, one fairing is really not needing a lot, so besides me thinking that Pro-Seal is overkill to get the seal waterproof I don't want to waste a lot of that stuff either as it is not really cheap. I will let the final installation sit until I have at least both fairings ready for installation or when I come up with a more economic way of sealing the seam.

Nav Light Ready for Wiring

So, today I took a closer look at the cured epoxy built-up on the nav light fairing. As I thought, way too much epoxy! I went everywhere, trying to escape the sticky crowd when I put it on the wingtip to shape it. Unfortunately it also clogged up area where it was not supposed to go and I hadn't put wax on there as I just didn't anticipated it would be able to get there. I'm speaking of the holes for the attach bracket which will get a nut on the inside of the fairing and that nut wouldn't be happy sitting on anything but a flat surface.


You can see the tool of choice in the right of the picture. I will use this to remove the excess epoxy and to carve out a flat surface for the nuts.

Voila, a bit too much removed but I can rebuild that easily.


Which I did in the following picture. Along with taking a look at the final appearance with the light mounted. Really good looking! BTW: I checked the nav light at that point in time with a 12V battery. It works great! It would even work better if Van's had me run 3 wires through the wing instead of just one. The unit supports separate control of strobe and position light as well as a synchronization wire for the strobes, so they would fire at the same time. While the latter is not really necessary (cuter though) having separate control of the strobe portion would be desirable. Oh well, the string is in there and I can add that if it really bothers me.


And finally I thought it was a good idea to glue those stop nuts to the epoxy to be able to tighten screws that would get loose over time (despite the stop nut feature). So I added some more epoxy to the inside to keep the nuts in place. The main reason was that I noticed when playing around with the light that it would NOT slide onto the attach bracket if on of the front screws was a bit too tight. If I find out about that after I riveted the fairing on then I wouldn't have any way to loosen (or tighten) that screw for making the perfect fit for the light.


Well, that was it. On to the wiring part...

Nav Light Coming Along

Right around the last weekend I must have caught a nasty stomach bug that brought me down on Monday. I swear, I never felt that tired in my life. All I could do was sleep the whole day and then some. So there was no way I could have done anything in the shop the last few days.
Today was the first day I got a tiny bit better. At least I wasn't so sleepy anymore. So, I tried to do a little something on the nav light installation and if it was just to get my mind off that achy stomach.
I trimmed back the fiberglass to the scribe line. I wasn't really sure how to do it. The manual says to use shears within 1/16" of the scribe lines and to sand down the rest. Well, when I tried to use the tin snips on the fiberglass I could immediately see how hard it is to cut a precise line and also that the fiberglass was delaminating around the cut. Both didn't look really appealing to me as either one could mess up the part for good.
What I did was to sand it down entirely with the high speed die grinder. A messy and dusty job but no delaminating and pretty precise too. The last 1/16" or less I sanded down with some 100 grid sandpaper pulled on a 2x4". That worked pretty fast and the result looks good. If anybody has a better idea how to do this with less dust, please let me know.
Having removed the outer brim of the part I fitted it to the wingtip and removed some more material with the sandpaper and then drilled the holes through the outer flange into the wingtip. There's not really a good way of clamping the part to the wingtip as there is no flat surface anywhere that would take a clamping force without slipping off. So I suggest to first drill the hole through the fiberglass part and then holding it firmly in place on the wingtip to drill through the metal. That way it is less likely to slip. Then cleco as you drill along.


After this step, they make you drill into the wingtip closeout and the lower flange of the fiberglass part. Again, cleco as you drill these. The next step that reminded of my old days when I was building RC model airplanes, was to fill the void between the outer flange of the fiberglass inner area and the wingtip with floxed epoxy. You add as much epoxy as required to make it not run from the mixing cup, which means it is practically kneadable. Never add the flox to the resin before you thoroughly mixed the hardener with the resin as the flox will prohibit a good mix.
Unfortunately I didn't have a slower curing epoxy. I was even running to Home Depot to get some 20-minute epoxy only to find that all they had was the quick curing stuff around 5 minutes. To avoid insane HazMat shipping charges on something so simple as a 20-minute epoxy I got another set of bottles of the 5-minute stuff and vowed to just work faster.
So, I prepared everything at the wingtip, applying car wax ahead of time, getting the fiberglass part ready, putting wipes and alcohol next to the wingtip, putting release agent (car wax) on the tips and mechanics of the clecos, etc. Then I mixed the stuff and added the flox. Boy did it cure fast! I barely had enough time to apply it to the outer flange before I could feel the heat coming from the mixing pot. I rushed to the wingtip and put the part in place, pushing hard to squeeze the excess (thick) epoxy out to the sides. The clecos went in and I quickly wiped off the spilled epoxy from the around the wingtip. Wow, just in time. The curing kicked in and I could feel the heat coming from the nav light fairing.
I noticed that I had to do another run as I had applied the epoxy filler only in the region the manual had told me. The far front and aft of the fairing where not touched but I could see a small gap in the front and aft section as well and particularly in the front I didn't want to have that. When riveting that gap will put stress on the fiberglass part and it might crack over time.


So after a while I took the part off, cleaned off the wax in the aft and front areas of the outer flange and prepared for another run. That went on quickly and let the part sit for a couple of hours to let it cure.
Taking it off after that showed that there was way too much epoxy used on the first run. It built up a shelf inside that added a lot of unnecessary weight to the part. When finally cured I will have to sand this off again. Van's said to mix 2-3 fluid ounces of epoxy which I think is way too much. Take it easy and build it up in multiple stages if you really have to. Chances are 1 fluid ounce is sufficient for the whole flange.

That was it. Sounds like a lot happened but everything was done in about an hour.

Left Wing Complete

With that fresh motivation from my visit to Denny yesterday, I was going to work today to finish the left wing.
First step was to create the bending tool to bend the tabs on the wingtip closeout. Fortunately I had a scrap piece of 3/4" wood lying around. This was quickly turned into the required tool.



With the help of a digital protractor that provided the reference for the angle to bend, the tabs of the wingtip closeout were bent in a few minutes. Nothing really complicated and don't fuzz around trying to bend them to 1 degree of precision. This is certainly one of those Oregonian jokes that they try to slip in once in a while.


Trial fitting it showed that everything fit just fine, except for the one on the nose that had to be bent 116 degrees. It was easy to just bend it as required to match the shape of the nose skin. Clecoing it into place was the next step.


Except for one spot in the nose area of the closeout I was pretty happy with the fit. This one spot has to be addressed though as it looks like a nasty spot which could create some nasty noise.


And from the side view:


Now it was time to seat the rivets and ready for the fun part.


Here's another spot that I don't really like. I'll look into that when getting ready for painting and I might just fill this gap with some caulk or Pro-Seal to allow the paint to cover it up. This is located at the lower end of the main spar.


And there I was with a riveted wingtip closeout!


Not much more to do than to fit the last part in. Some match drilling is required here, although it fit in just perfectly.


BTW: For some reason Van's is very casual telling you which holes to rivet and which not to rivet on this last page. You'll have to figure it out yourself by looking ahead and understanding in advance how the pieces are supposed to go together. Also they don't tell you how to overlap the parts on this page. Try to think aerodynamics to make a good decision.
Then take a look at the previous image and note that the triangular piece is sharing one hole in the front with the wingtip closeout part!

Match drilling (without turning the wing over) and riveting was quickly done.


Leaving me with a finished left wing! 4 hours were spent today, bringing the total of section 17 to 53 hours so far. No bad, considering that I am priming. Let's see how the right wing goes ...

Some conclusions. The nose area thtat appeared to need some trimming is not so bad after riveting. Just a slight overlap that can be filled before painting.



For the nav light you should not rivet three holes. Unfortunately the manual doesn't tell you that and you have to figure this out yourself. Or drill out the rivets after failing to do so, which is what I did on one hole. So look at the following picture and note the empty holes. One is enlarged from drilling out the rivet to aggressively. This will be covered by the fiberglass of the nav light. Am I lucky or what?



And finally a picture that shows how I let the wing skin overlap that little triangular end piece. Look closely at the corner were the rear spar and the wingtip closeout meet. That were I put the forward piece of the triangular closeout underneath the wing skin. Looks nicer I think.

What a Great Airplane!

No build activity today but instead I flew up to Phoenix to meet Denny Myrick, getting a ride in his recently finished RV-12 and updating his Dynon to V5.4.
Boy, what an experience! I flew in with my dragster RANS S-12S which I thought to be light on the controls and fairly responsive. Once I had my hand on the RV-12 that impression changed immediately. The RV-12 is so light on the controls, you can easily maneuver it with just two fingers on the stick slightly pressing in the direction you thought you want to go and it responds instantaneously. As soon as you let the pressure on the stick go, the plane stops moving. Simply an amazing experience, seriously.
I think this short flight today gave me the will to go through the inevitable longeron bending process and other less enjoyable tasks!
And by the way, I really don't understand what all the fuzz about that Dynin D180 is that you read on the forum these days. The unit behaved perfectly without any hic-ups or anything and the update process was as smooth as it could have been (besides being a bit lengthy going through that RS232 bottleneck).
All in all, a perfect day. I logged 3 hours in my S-12S and secretly some 15 minutes of stick time on the RV-12. I definitely had an RV smile on my face the whole flight back to Tucson - and I wasn't even sitting in one.

On Last Page of Section 17

I put 3 more hours in today and got myself onto the last page of section 17. The wingtip is almost finished.


I started on the bottom which was easily accessible as the wing was still bottom up. Riveting the little strip and the outboard aft rib and the grip handle into place was quickly done.


Way too quickly it seemed as now I had to determine how to proceed. The next steps would have required to turn the wing bottom down to get easy access to the top where more parts were to be riveted on. I tried to do it alone but decided after some time that it would be too dangerous to damage the wing in the process. On the other hand I didn't want to call it a day after less than 30 minutes of work that I had put in so far and wait for my wife to come home and help me turning the wing.
The only way to continue seemed to work head's up. So, I tried to cleco on the parts.


and the upper (or lower) part of it as well.


That wasn't too hard! So I went on riveting while lying on my back, using a mover's dolly as a rest for my back and to insulate me from the icy ground,



Now it felt like my muscles started to cramp because of the unusual load and the awkward working position I was in but I kept pushing on. This was the hardest part, now the edge ribs were going on and I could work from the side not fully lying on my back.


The rear spar had to get trimmed a little bit to allow the rear rib to slide over it. The manual said this was ok to do.

That one was quickly riveted on and I continued with the forward edge rib which had to get heavily fluted to match the curve of the wingtip. After three attempts that one looked fine and riveting was just as easy. The only thing that took some time was to determine if the forward edge rib went OVER the rear edge rib or UNDER it. Unfortunately, the manuals are not clear on that and the drawings are so small that it is hard to determine it. I finally decided to put the forward one over the rear one as it seemed to look better and made more sense from an aerodynamic standpoint. I don't think it would matter a lot, one way or the other.


FInally a shot from the lower (upper) side.



And all that without turning the wing. Now, let's see how my back feels tomorrow. I expect some delayed but nevertheless obvious objection... I hope it won't be too bad as I am flying to Phoenix in the early morning to meet Denny Myrick to update his Dynon to version 5.4 and also to get a ride in the -12.

I'm really excited!

Wingtips Ready for Assembly

On Veteran's Day I didn't get that much done. All I could do was to wipe the wingtip parts with acetone and prime them. This time with the larger jet and I'm not sure how to read the results. The overall difference was that I shot the coats much wetter than usual. This allowed the paint to settle and flow before drying. The relatively cool weather in Southern AZ helped with that too. Unfortunately that also screwed up my rhythm and I spent quite some waiting for the paint to dry before I could remove the parts from the spraying rack.
What was still the same with the larger jet was that I had to use a relatively high pressure to get a usable paint spray of 50-55 psi at the gun and I still get some paint built up at the air holes on the nozzle. So, right now I'm a bit undecided about the result of this experiment and if this was actually an improvement or not. Any suggestions from the gentle readers of this blog?

Here's a shot of the wingtip parts after priming:

More Wingtip Preparation

Finally a picture of the wingtip cutout for the nav light. This is for the left side.


The left wingtip parts are ready for priming, so I worked on the right side tonight. I prepped them all except for the wingtip closure part that still needs the trimming for the nav light. I figured that by the time I need that one I had a lot more priming happening as the skins haven't been processed yet either.
The parts for the right side are drying now and tomorrow I will shoot the primer. This time with a different jet and I'm curious if this will result in a smoother layer!

Preparing the Wing Tip

I spent two hours tonight to prepare the parts for the wing tip. Mainly deburring of edges and holes of the skins. I also marked the cut out for the nav light and cut it out. I used a #19 drill to start a hole, widened it with the step drill (all the way through) and then used the nibbler to roughly cut out the hole. Fine trimming was done with the angle die grinder and a pink die. This resulted in large burrs that I removed with a file and smoothed the edges with a 1" Scotchbrite wheel. Turned out to be pretty good - yet I forgot to take a photo. I'll add that when I get back from work tomorrow.
By the way, I've noticed something funny about the Lighting Kit. As it was one of the optional kits coming out way after the all the other kits, the manual is laid out for adding it to an already built RV-12. Now, that I am adding it while I go, I could do it much easier and faster but as I don't have a manual describing this approach I have to read section 40 and fully understand what the purpose of each step is and apply it to my situation. This takes significantly more time and voids the advantage of adding it during the build completely. I wish there were two sets of manuals available. One for adding it later and one for adding it during the build with updated pages for the sections.
Tomorrow night I will probably start the surface prep on the wing tip parts as I finished all the deburring tonight.

Just a Little Deburring...

Sunday was my day off from building, but I guess you know me enough by now to know that I still had to do at least a little something. And that little something was taking that ugly concave hatch off and bend it to shape. It now blends in with the curve of the wing just perfectly. I let it off for now though as I want to prime the inside with the next stack of aluminum.
The other thing I was doing was getting ready for working on the wing tip. The bigger sheets had already been primed but there area handful of small parts that I hadn't touched yet. So I retrieved them and started the deburring process on the holes and edges. I also bent the outboard wing handle insert for both wings and started to wonder how I am going to get paint evenly sprayed into that hole they are going to create...
The rest of the day I was busy assembling all the new "toys" I bought at HF. Among them a workbench that I mounted the 6" Scotchbrite grinder on to get it out of the work shop and with it all the dust it creates when I use it. It's now outside in front of the work shop and needs much less clean up after a deburring session as the wind is taking care of what I had to do with a vacuum before.
As outlook for this week. It appears that I will focus on finishing the wing tip and get the nav light installed as well. I hope to be able to completely finish off the left wing and put it in the wing cradle. I am not sure how to celebrate this major construction step when I accomplish it. Any ideas what to do???

Left Wing Almost Done

So I went back to the wing doubler that I had left in the evening. The fit was really off and I decided to remove it. After reading a bit about other experiences with the doubler on the Van's Airforce Forum I decided to work around the problem of the pre-dimpled holes by clamping the doubler in a vise with wood as a buffer and bent it right behind the line of rivet holes, about 3/8" from the edge. This worked pretty well and a visible crease was created that ensured that once the rivets were set, the edge would still be in touch with the skin.



So I went on clecoed the doubler back in place and also got ready to finish the rest of the nose skins.


The riveting didn't take a lot of time and soon the wing looked like this:


Now it was time to turn the wing over again and get the inspection hatch installed. 10 nutplates had to get prepared and riveted in. A bit less than an hour later the hatch was installed.


That's how I left it. The wing would fly right now although the outboard area sure wouldn't look good. So, I'm not quite done just yet, but almost there.
BTW: Later I noticed that I will have to remove the hatch again and do some more work on it. It is currently slightly bulging inside and I want to bend it to follow the shape of the wing more. I might have to add a stiffener on the back if it wouldn't stay in its shape. Currently it just doesn't look nice.