Horizontal Stabilizer Complete!

A few short hours later, and I was rewarded with the completion of the biggest part yet on this journey! It's really incredible how strong (and light) the HS feels once it's all together, especially after feeling how flimsy all the pieces are by themselves... it truly is a real-life example of a whole being more than the sum of its parts...

The completed HS, right side.

The completed HS, left side.

Today was also a pretty exciting day because I got to see a real live RV-10 up close! Our local EAA chapter's flight advisor, Dave, who has a remarkably long list of accolades as both a pilot and a flight instructor... just so happens to have built one himself, and regards it as his favorite airplane. He was kind enough to invite Sarah and I up to his hangar and give us a full walkthrough... along with opinions, advice, and words of encouragement. Hopefully sometime soon we'll have a chance to go flying in it! For now, here's happy Mike sitting in the same model of plane he is building, for the first time:

Horizontal Stabilizer Assembly

Wow there are a lot of rivets on this part! The dimpler got a good workout today, that's for sure:

The homemade C-frame dimpler in action

After dimpling the skins and prepping the rest of the parts, it was time to begin actually assembling the HS.

The skins set in their cradles, ready for final riveting and assembly

The nose ribs, riveted into the skins.

First, the nose ribs were riveted to the skins, after which the whole front spar, rib, and stringer assembly went in as one part. A few hundred rivets and many hours later, I had about half of the HS assembled. Dinner plans with friends brought the day to a close, which was probably good since I was starting to get very tired of the monotony of the whole riveting process!

HS Front Spar Assembly

As promised, work continued today on the HS. I finished priming the parts for the front spar and ribs, and began assembling the front spar. This included riveting the main attachment brackets to the doubler and spar with a healthy number of rivets... this thing has to be strong, and what do you know, it is!

The HS front spar, just after riveting

The spar, doubler, and attachment brackets, laid over the instructions calling out the appropriate rivets.

That's all for now... next thing will be to assemble the ribs to the stringers and start putting the whole assembly together!

HS Rear Spar/Trim Tab Work

A lot of the project is on hold until the first coating of primer that I applied yesterday has had 48 hours to cure so I can finish the job. However, the HS Rear Spar was already fully primed and could be assembled, so I focused on that. I riveted it and its parts together per the plans in sections 8-2 and 8-3. I also added two grounding nutplates near the number 2 and 4 elevator hinges, in case I want to add static wicks in the future.

 The #2 elevator hinge bracket, with the grounding nutplate just inboard of it.

 The #4 elevator hinge bracket, mirror image of what was done to the #2 bracket above.

 

The #3 (center) elevator hinge, with all rivets holding the doubler in place shown here.

The other side of the HS Rear Spar, with the hinge bolts torqued properly into place.

While waiting for things to do on the HS, I turned my attention briefly to the rudder. The proseal had cured enough to move on to riveting, and I thought it would be best to rivet the trim tab trailing edge first, since if I messed that up it would be easier than redoing the whole rudder! I had the rivets alternate directions to make things more even (probably for appearance more than anything) but I think it did help it stay straight too. There are a lot of posts online that warn builders of this step, so I was going pretty cautiously... It actually turned out to be a lot of nervousness over nothing, it went together very easily thankfully!

The rudder trim tab, with the trailing edge riveted together.

I'm not sure if the picture does it justice-- looking at it now, it appears to be a little wavy, but it actually came out very straight. There is one spot near the bottom corner that we'll need to fill in slightly though, because the corner got rounded off too much on one side, but I'm pretty confident it won't be that big of a deal. I'll see if I can take a better picture of it once it's all assembled together.

Sarah found the mother load of primer across town today, and so we bought 6 more cans... hopefully that should be enough for the rest of the empennage! Now we wait until tomorrow to finish priming and then begin the final assembly of the horizontal stabilizer.

Horizontal Stabilizer - Day 4

Tonight was a fun night! We continued onto section 8-9, adding the stringers and rear spar to the HS assembly, and clecoing the entire skin into place. Now comes the fun task of final-drilling every single hole in the skin, through any combination of ribs, stringers, and spars. Sarah and I decided to split sides and each work either the top or bottom skin. First, though, we needed to figure out which drill was the lightest one so that Sarah could use it ;-)

Ergonomics [and Chivalry] 101: Sarah determines which DeWalt 14.4V drill is lighter using the epoxy-mixing/postage scale.

After an arduous drill-usage negotiation, I took my 2.1kg drill to the bottom skin while Sarah took her 1.8kg drill to the top skin, and we spent the next several hours final-drilling every hole in the horizontal stabilizer. Just as drilling was coming to a close, our friend Brannen stopped by to watch and help with the process. After disassembly, all the holes needed to be deburred and then dimpled, which everyone including our dog Mesa was happy to watch:

Everyone, even the dog, was told to act serious while Mike works.

The dimpling process is getting pretty familiar by now. I've learned that putting one handle of the squeezer into a vice makes it a lot easier to run it through each hole in each part in the least amount of time. An hour or two of dimpling later, and it was prime time!

The HS bits, 97% primed

Unfortunately, I ran out of primer around midnight. This mostly affected the HS front spar, but many of the parts could have used a little more attention to the corners, etc. I quickly hopped over to Walmart (dressed to the 9's, of course) in the hopes that they would have some more in stock, but alas they were still out from the last time I had checked a couple weeks ago. This means that I'll have to wait two days before priming again, since the instructions say that additional coats must be applied within 1 hour or after 48 hours. Time to call it a night!

Horizontal Stabilizer - Day 3

Made it through almost 4 pages of the plans today! While yesterday dealt with parts going on the HS rear spar, today was all about the HS front spar. I started by making the HS-1013, HS-1014, and HS-1015 spar caps and stringers out of their raw materials:

Starting Section 8-4

The familiar process of measuring, measuring again, cutting, coarse sanding, coarse filing, and fine filing began. Sarah was away today, flying to KPRO (Perry, IA) in a Cardinal with some friends to attend a meeting with (and join) the 99's. Super excited for her, and jealous that she got to ride in a Cardinal :-)! In her absence, my friend Roy stopped over and helped keep me company with the fabrication process. The spar caps then needed to be clamped into the HS front spar and match-drilled to the specified holes. About 4 hours later (including a quick trip to Sears to buy more 3/32" drill bits), I had these parts in front of me:

At this point, we were in the middle of section 8-5, which called for the temporary assembly of the HS front spar, doubler, caps, and HS attachment brackets. I got a kick out of the fact that the plans called out to use "something flat" to align the brackets square against the spar.

The plans for temporarily assembling the HS front spar components

My "something flat" was a scrap 1"x1" piece of square metal stock, left over from when I built my C-frame dimpling tool.

It turns out that a total of nine holes are necessary to rivet these brackets to the front spar (only 4 had been drilled when the above photo was taken). Needless to say, the drilling process had my full attention! Anyway, some time later I had completed everything in this section except for the riveting portion, and was able to move on to the ribs in section 8-6 thru 8-8.

Even though Sarah was away today, I still need to give her credit on this step, since in anticipation for this section she had already unwrapped and deburred all of the HS-1004, HS-904, and HS-905 ribs a few days ago during some downtime, allowing me to blast right through an otherwise lengthy and tedious deburring task. All that still needed to be done was cut out the special parts of four of the center ribs, bend the flanges to spec, and then make some wooden cradles to hold the HS upright as it is assembled. A short while later, I had the HS skeleton clecoed together, along with the skins set in place in their cradles:

The HS skeleton, next to the R and L skins set in their new cradles.

Today ended with clecoing the skeleton to the inside of the skins. Now for the first time, we have something that looks like a horizontal stabilizer!

Last pic of the day: End of section 8-8, step 8!

Horizontal Stabilizer - Day 2

Spent some time up at KIIB today to attend a free ground school they held on weather. We had a great time hanging out with everyone up there as always, grabbed some lunch and didn't make it back until well into the evening so today was another relatively short day of work... but made some pretty cool parts! Since I am skipping the riveting steps for now to save them for later, I moved on to Section 8-3, assembling the inboard elevator hinge and fabricating the front spar attachment brackets out of raw angle aluminum. These brackets took several hours to make, and I have to say I'm pretty proud of the result!

The spec for the HS-1008 brackets

HS-811 Inboard Hinge, and HS-1008-R/L Brackets

Fabricating the two attachment brackets paved new ground for me, for sure. As I started on this step, I wasn't quite certain what part I was actually making, or what it would eventually be used for. However, it seemed that the thickness of the angle aluminum (AA6-187 x 2" x 2.5") combined with the exacting tolerances (to the 1/32nd of an inch!) specified in the plans meant that this must be a pretty important part. The realization slowly started to sink in, oh yeah, these are the two brackets that will attach the HS to the rest of the plane... don't mess these up! With some slow and careful measurements/cutting, combined with a lot more patience than I usually exhibit with small 2 square inch parts, I think they ended up coming out pretty darn close to spec. :-) Oh yeah, also, it turns out aluminum makes a great heatsink! Cutting these with the bandsaw resulted in some pretty toasty parts at times-- the word "yeeeeow!" may have been heard once or twice in the garage tonight...

Rudder Delay - Starting on the Horizontal Stabilizer

Indeed yesterday was one of the most perfect days to fly yet this year. We took the 172 up for a few hours, visited some friends up at KIIB and did some t&g's to try and brush some of the winter rust off... I haven't flown nearly enough these past couple months. It felt great to be in the air on such a beautiful day though, it reminded me why I'm doing this project in the first place!

I started out today by inspecting the Proseal on the rudder since it's been two days, only to discover it was still quite wet. This concerned me at first, but then I went online and did some research to discover the stuff I had bought from Aircraft Spruce was actually of the "B2" classification (see this helpful link) and needed at least 4.5 days to cure in ideal conditions (not two as mentioned in Van's plans). Anecdotally, there are a number of posts online that indicate it can sometimes take a lot longer if the temperatures aren't warm enough, and since it's been fairly cool/cold here in the garage when the furnace isn't on, it will likely need even longer than specified. So I re-clamped the whole thing back together and brought it all down into the basement where it's out of the way and warmer than the garage. Looks like I'll be giving it at least a week or so down there to make sure it's cured... so in the meantime, on to the Horizontal Stabilizer!

No pictures from today-- lots of deburring/prep work but no real visible progress worth taking pictures of. Finished section 8-2 steps 1-4, which was mostly just the initial prep work on the HS rear spar and doubler: match-drilling, countersinking, and deburring as specified. I plan on holding off on the riveting portions for now, so that I can assemble a pile of parts to scuff, acetone, and prime all in one sitting. Lots more to do on the HS!