Matt's RV-7 Project » Vertical Stabilizer

Misc stuff

Matt — Mon, 26 Mar 2007 01:33:54 +0000

I spent the whole day in the garage but didn't take many pictures. I guess I didn't actually get all that much accomplished – mostly I puttered and cleaned up the garage. It was great to be outside in the nice weather though.

One of the pre-tail-mounting chores I've been meaning to do is drilling the holes for the strobe and nav light wires that will go through the vertical stabilizer spar into the rudder. I picked the same location as Dan for much the same reasons – with the taildragger there aren't many other good choices for where to run these wires. I drilled a 5/16" hole for the strobe cable and a 3/16" hole for the nav light wires. Both holes are a little oversized so I can use a few layers of shrink tubing and some RTV to protect the wires from chafing.

Another day, another round of filling and sanding empennage fairings. I'm just doing a little bit every work session, fitting the glass work in between other tasks that are more fun.

I rearranged the garage a bit, and made a little table out of a sheet of plywood and a couple sawhorses. This is where the canopy is going to sit while I work on it. Yes, I've decided to work on the canopy some more before I put the airplane on the gear and mount the engine. Matthew convinced me that it'll be easier to get to it while it's down low and not high up on the wheels. Plus it seems to be warm enough these days to start thinking about working with plexiglass again.

I got out the canopy frame to make sure it still fits – yep:

Belt and suspenders

Matt — Fri, 11 Aug 2006 02:29:30 +0000

Back from a short vacation. We did a bit of rafting and a bit of hiking. Here's us on top of a mountain. It was very windy.

Just for grins, I called Van's and asked if there were any issues with the edge distance on the top two bolts versus the tailwheel weldment. Ken Scott said, roughly, "As long as you have any edge distance whatsoever it's no problem at all, but if you're a real belt and suspenders type of guy you could put another AN3 bolt in the middle." Belt and suspenders? Sign me up!

So here I've put an extra 3/16" bolt in there to help me sleep better at night:

Man, there's all kinds of stuff in there. Actually the whole tailcone is filled with dropped washers, nuts, clecoes, and metal shavings galore. After I get the empennage attach chores done I'll have to clean all this out.

Working on empennage attach some more

Matt — Sat, 05 Aug 2006 20:47:59 +0000

On an impulse, I bought this cool angle drill that was on sale at Brown Tool. I didn't get a chance to use it today though, since I need to replace the air fitting and it's really stuck on there tight. It'll have to wait until I reattach the vice to the bench.

I carefully positioned the F-781 forward spar attach plate so it was lined up vertically and on the centerline of the aircraft, then drilled it to the horizontal stabilizer spar. The vertical stabilizer spar is just floating there in this photo, it's not clamped or attached at the moment. You can also just barely make out the 0.032" shim I made to go between the plate and the spar, since there was a gap there. It's held in place with scotch tape in this picture.

I used a metal straightedge to make sure the aft end of all three rudder hinge points were in line, then I dropped a string down through the bolt holes just to double check. Small movements at the front end of the stabilizer have big effects back here in terms of getting the hinges to line up.

Once everything was good and lined up, I match drilled the holes in the attach plate through the VS spar, or at least as many as I could reach with the angle drill. I also drilled and reamed the pilot holes through the attach plate and HS spar up to 3/16".

I removed the stabilizer from the airplane to finish drilling the remaining rivet holes.

There is a tooling hole in the aft bulkhead exactly where the plans call for you to put the lowest of the three 1/4" bolts that attach the bottom part of the VS rear spar to the aft bulkhead and tailwheel mount. I center punched and drilled a #30 pilot hole right in the middle of that tooling hole, through the tailwheel mount.

Then I put the vertical stabilizer back on, bolted everything down, and back-drilled through the pilot hole into the stabilizer spar. Then I drilled the resulting hole up to 3/16" for temporary fitting.

I unbolted everything and took the stabilizer back off, then marked and drilled the other two bolt holes through the lower hinge bracket, using the dimensions on the plans.

Then I bolted the stabilizer back in place yet again, drilled and reamed all three bolt holes up to 1/4", and put some temporary bolts in.

Here's an inside view. There is acceptable edge distance on both of the upper bolts – I was worried about this – but they're a little closer to where the radius of the bent-up edges start than they probably should be. On the left side, I may have to grind down the washer a tiny bit to get it to lay flat. If I'd moved the holes inboard about 1/8" each from where the plans have you put them, it would have been perfect. This is okay though. This entire area has you measuring and drilling blind, so if it comes out halfway decent you've done about as good as you can.

This looks a lot like it did a few days ago, but now all the holes are drilled and the vertical stabilizer is actually bolted in place. This thing is completely solid – you can grab ahold of the end and give it a shake, and it won't budge. I suppose that's a good thing for a 200 mph aircraft.

I just have to deburr, prime, and rivet some stuff, then it can be bolted in place for good. Actually though, I will probably take it off again and just put some smaller bolts through the tailwheel mount instead. That way I can roll the fuselage around without the tail, to save space in the workshop.

But first, off to Colorado for a mini vacation.

Still working on vertical stabilizer attach

Matt — Tue, 01 Aug 2006 03:05:00 +0000

I measured about fifty times to make sure the vertical and horizontal stabilizers were absolutely perpindicular, then I drilled and bolted the up elevator stop to the fuselage and the VS spar.

I still have to fit and attach it in two other places, but this is a start. It's also all I have time for tonight!

Working on vertical stabilizer attach

Matt — Mon, 31 Jul 2006 02:49:18 +0000

Well, I got back from Oshkosh. Was busy working most of the time, but I did have a little time to sneak off and check out the latest gadgets. I also did some engine shopping. Anyway, tonight after the incredible heat subsided a bit, I spent a little time on the project. Here is the up-elevator stop prior to cutting:

Here it is all cut and with pilot holes drilled.

Here's the up-elevator stop being fitted to the aft fuselage. This piece is also one of the three places where the vertical stabilizer attaches to the rest of the airplane. I wasn't quite ready to commit to one particular stabilizer alignment yet, so I didn't drill the other set of pilot holes (from the elevator stop through the VS spar) tonight.

This whole process of fitting the empennage is very fiddly. Must go slowly to avoid building a crooked airplane.

Working on empennage attach

Matt — Mon, 24 Jul 2006 03:00:42 +0000

More work on the empennage attach chores today. I hauled the elevators down from the airplane storeroom, and spent a bit of time filing metal away from the left elevator where I noticed it was a little close to the outboard edge of the trim tab. Good clearance all around now.

Then I temporarily mounted them to the stabilizer. Hey cool, the tail has moving parts now!

The next step in the plans is to make the elevator pushrods. I cut them to length using my handy dandy miniature chop saw:

I had previously picked up a quart of this SEM self-etching primer, which is pretty similar to the GBP 988 I've been using elsewhere, just in liquid form instead of a spray can.

To prime the insides of the pushrods, I taped over one end, poured liquid primer down the other end and taped it up, and then sloshed it all around inside. Since these pushrods are so long, especially the aft one, using the liquid primer here was easier than spraying a ton of primer down the inside like I did with the previous ones.

After the insides were all coated with primer, I uncorked the ends to let everything dry out.

While the pushrods were drying, I got out the vertical stabilizer attach plate and clamped it in place to test the fit.

One of the first things the plans have you do when you begin the process of attaching the vertical stabilizer is to cut 5/8" off the VS front spar. Uh, gee guys, it sure would have been nice to have known about this when I was building the thing in the first place. It would have been a lot easier to trim the spar before it was, you know, all riveted in place and stuff. Further evidence that the RV-7 is a Frankenplane: Wings and vertical fin from an RV-8, fuselage and rudder from an RV-9, and instructions from who the heck knows where. Oh well, they fly nice and look real purty.

I got as far as clamping the vertical stabilizer in place before I had to knock off for the night. I'll be away at Oshkosh for the rest of the week, but it's nice to know that I have this thing-that-looks-a-lot-more-like-an-airplane-now waiting in the garage for when I get back…

Finished Vertical Stabilizer

Matt — Sun, 26 Jun 2005 00:56:51 +0000

Mary was awesome again and came out to pound in the skin-to-forward-spar and skin-to-middle-rib rivets:

Then the rear spar gets clecoed on…

…aaaaaaand, done. The vertical and horizontal stabilizers are finished, hooray!

Got the VS ready to rivet

Matt — Fri, 24 Jun 2005 02:17:31 +0000

I didn't get to fly as much tonight after work as I'd planned, so I got to work on the RV just a little bit. I swapped air connectors so I could run the rivet gun – as an aside, boy do I not like using the air tools without my handy swivel connector and my lightweight couplers – and smashed in the rivets that attach the ribs to the lower part of the forward vertical stab spar. Then, everything gets clecoed together:

I'll have to make sure to be extra nice to Mary so she'll be willing to come out to the sweltering garage to pound in these rivets this weekend…

VS spar riveting

Matt — Thu, 23 Jun 2005 02:02:26 +0000

I managed to find enough normal-sized air couplers laying around the garage to get the squeezer hooked up, so I was able to get the rear vertical stabilizer spar riveted together:

(Note that I keep an ample supply of lubricant available to make the work process go smoother)

The next step has you rivet the VS ribs to the front spar. I managed to get the upper and center ribs attached, but the geometry of the lower rib/spar interface has me stumped. I guess I'll either figure out a way to get the squeezer on those rivets, or I'll just smash them with the rivet gun. In that case, I have to wait for the new air fittings to arrive on Friday so I can get my regular air lines hooked up again and run the rivet gun.

Primed VS parts (again!)

Matt — Wed, 22 Jun 2005 02:00:55 +0000

Tonight I primed the replacement vertical stabilizer spar parts…

…and I also decided to lightly scuff and prime along the rivet lines inside the skin:

So I was all set to start riveting this baby together, when my Avery lightweight air coupler somehow came apart.

Of course one of the five little steel balls rolled off into a dark corner somewhere, so even if I could get the stupid thing back together, it probably wouldn't work right. Oh well, a new one is only six bucks, and I was going to pick up a few other things anyway, so back to the Avery website we go.

Back to the VS again

Matt — Tue, 21 Jun 2005 02:40:32 +0000

Another week has gone by without much of a chance to work on the plane, but the house painting is now finished. Mary is happy, and thus I continue to have a riveting partner. Tonight I dimpled and countersunk the lower parts of the VS spar and spar reinforcement, and deburred all the remaining edges. Ran out of time to clean and spray primer… but I've done quite enough painting lately, so it's somewhat okay.

Back to the VS

Matt — Thu, 16 Jun 2005 01:58:22 +0000

Now that the HS is finished, it's back to the VS for yours truly. I match-drilled the new spar reinforcement bar to the new VS spar, and then set about cutting out a new set of lightening holes. I discovered that the non-removable pilot drill in my fly cutter had gotten bent somehow, so this time around I decided to try a set of hole cutters from Hougen by way of Cleaveland Tool:

They were outrageously expensive but they do a good job of cutting nice round holes, and give me the willies somewhat less than the fly cutter. The other aspect I failed to realize until after I'd bought them is that the set doesn't include a 1 ¹/₂" cutter, only 1 ³/₈" and 1 ³/₄" ones. Rather than spend yet more money special-ordering the correct cutter size, I decided to just cut the specified 1 ¹/₂" holes ¹/₈" undersize using the next smallest cutter I had. Since the lightening holes are optional anyway, it just means that I have a spar reinforcement bar that's slightly heavier than it needs to be.

Let's see… five 1 ¹/₂" holes that are each undersized by an eighth of an inch, in ¹/₈" thick aluminum… 0.224 in³ of extra material, at 2.643 ^g/_cc… the tail of my airplane will be a third of an ounce heavier than it might otherwise be. Yeah, I think I can live with that.

For the remaining two 2" holes I did have the right sized cutter, so I finished those too and all my lightening holes are now drilled. Deburring will have to wait till tomorrow when I can run the air tools without waking up the neighbors.

Dimples

Matt — Sun, 05 Jun 2005 02:00:43 +0000

Matthew Brandes came over tonight to check out the RV-7 factory. He pointed out that the dimples I'd done with the DRDT weren't deep enough. Dang. I had originally been lazy and not bolted the DRDT to the bench, so I wasn't able to yank on the handle with sufficient force to set the dimples properly. So, I had to laboriously re-dimple the three skins I'd done so far (2 HS and 1 VS) after setting up the DRDT so it can be quickly attached to the bench and then removed, which is so boring that I won't bother to post a photo of it.

Oh what the heck, here's a photo anyway:

Ordered new VS spar parts

Matt — Tue, 10 May 2005 15:31:28 +0000

After thinking about it a while, I decided to go ahead and order parts to build a new vertical stabilizer spar. The pieces are relatively cheap and I'll feel better about the airplane. The old spar could probably have been made to work just fine, but I don't want to be lazy and accept work I know isn't as good as it could be.

Also ordered some NAS1097 rivets, which will probably come in handy later on when riveting skins.

Finished VS spar, sort of

Matt — Tue, 10 May 2005 02:00:28 +0000

Occasionally, living in Kansas has its advantages – like the way I can order something from the Yard Store in Wichita and it gets here the next business day for like six bucks. Here's the new (rebuilt) rivet squeezer I received today:

It is a clone of the Chicago Pneumatic CP-214, but I don't know who actually made this one. It looks like it was built when FDR was president and has obviously seen a lot of use, but it still works great. Those 1/8" AD4 rivets I was having trouble squeezing by hand are no problem for this guy. In fact, a typical work session with the pneumatic squeezer goes something like this:

Me: Here is a rivet that needs to be squeezed. CP-214: DESTROY!!!

You get the idea. The folks who say this is the most useful riveting tool they've ever bought are speaking the truth.

Here I've set the rivets in the center elevator bearing assembly I was working on the other day:

…and then drilled the bolt holes that will attach it to the HS spar:

Then I switched back to the vertical stabilizer spar, seen here resting in the grass after receiving a little primer touch-up:

Although it looks okay in the photo, I'm not totally happy with the way it turned out. For one thing, I foolishly damaged some holes by trying to drill out three rivets with the wrong size drill bit. Must double-check drill size next time. Those holes will have to be filled with bolts, probably, so there goes the weight savings I picked up by cutting the optional lightening holes.

The other thing I don't like about the VS spar is that I oriented the rivets so the manufactured head is on the forward (internal) side and the shop head is aft (outside). While this is a purely cosmetic issue, it bothers me that I didn't think about which way I was going to put the rivets in so the pretty side would be out. Yes, this is extremely picky, but I am considering chalking this one up to practice and ordering new parts to build a replacement VS spar with the lessons I learned on this one. Stay tuned…

Reassembled VS rear spar

Matt — Fri, 06 May 2005 02:00:49 +0000

Not much time to work on the project tonight, but got the vertical stabilizer rear spar clecoed back together:

Dimpled the vertical stabilizer skin

Matt — Wed, 04 May 2005 02:00:46 +0000

This is my DRDT-2 dimpling tool. It's more expensive than the usual C-frame dimpler, but it rocks. It's easy to dimple one-handed, it's stress-free, and it makes no noise so I can dimple at night without waking up the neighbors.

I used the well-known trick of removing the blue plastic along the rivet lines using a wooden straightedge and a soldering iron, and it worked great.

Primed internal VS parts

Matt — Mon, 02 May 2005 02:00:08 +0000

Lots of work but not many photos today. Final-drilled the vertical stabilizer ribs and spars, dimpled, countersunk the spar doubler, scuffed the surfaces, cleaned with acetone, and primed with GBP-988 self-etching primer. This is not the absolute most robust primer that's available, but it's certainly one of the easiest to apply and it seems fairly durable. It's also on Van's official list of recommended primers, which must count for something. I also know that lots and lots of RV's are flying around out there with this stuff in 'em, and I don't think any have rusted out of the sky yet. I figure this airplane will last at least as long as I'm interested in flying it.

Started construction of vertical stabilizer

Matt — Sun, 01 May 2005 02:00:26 +0000

Today was a productive day. Spent a good long while unpacking the two big boxes and taking inventory. Everything was well packed and no parts were damaged or missing. Decided to start with the vertical stabilizer instead of, as the plans have you begin, on the horizontal. Not only is the VS a simpler piece to build, but the completed assembly is smaller and there's less to ruin when working the bugs out of the build process.

First real construction step was to debur all the internal VS parts, flute the ribs and straighten the flanges, and then cleco the VS skeleton together:

Next, on goes the VS skin, to be match-drilled with the underlying ribs and spars. At this point I've done maybe an hour of actual work, and already it's starting to look like something that might go on an airplane someday:

Here comes the first optional step – cutting the lightening holes in the rear spar doubler. Some people skip this step, but I decided to go for it. It only took an hour or so, and it saves a couple ounces. Yeah, it's only a couple ounces, but back in the tail at the end of that long lever arm, every little bit helps. Plus it looks kinda cool:

The fly cutter – or whirling implement of doom – is not my favorite tool to use. It's dangerous-looking and it makes a godawful noise when cutting through thick stock like this. But going slow, being careful, and using a lot of cutting fluid makes it come out okay. Some work with a Scotchbrite wheel afterwards and the lightening holes came out great.