This blog has been dark for a long time. I’ve still been working on the plane, but at a reduced pace. A lot of my time was spent on “honey-do” lists. I patched and painted the living room (3 colors), the dining room (3 colors), and the garage (2 colors + primer work). I managed to find time to cycle in the New York Century (I went for the 80 mile ride, not the 110 mile one this year). I also snuck in a 6 day trip to finish my instrument ticket (got it!). Made it to family day to visit my daughter off at college. Then a quick weekend trip out to visit my Dad on the West Coast. I also started a machine learning class online and have been working on a startup idea with my sister.
When I last posted, the elevator was still in a million pieces (well dozens anyway). It is now much further along. Here’s the journey.
At last, the ribs start getting reattached to the spars. You need to take some care to get the orientation correct between the left and right elevators. I had one set up on each of my two tables (left and right) and did a lot of double checking to make sure things lined up.
Next, the counterbalance skins get riveted to the the tip ribs. The fit is pretty tight. You start at the tip and work backwards. The instructions said to check for twist. Mine seem to have come out pretty straight. I’ll know for sure when these get mounted on the horizontal stabilizer.
The hinge for the trim tab goes on the left elevator. I used my longeron yoke to avoid deforming the hinge eyes. The blue tape marks a few holes that get riveted later in the final close out.
Then, it’s a bunch of back riveting. The ribs and spars get riveted to the skins. This is where the genius of the split ribs shows. My 5 foot back rivet bar was really handy here. I did, however, miss the bar on a rivet on each of the elevators. The dent isn’t too bad.
The bracket for the trim motor also get’s riveted in. 5 of the nut plates were riveted in earlier, but two get riveted in now (the two golden pairs of rivets. It came out pretty nice.
So I ended the day with some skins, ribs, and spars riveted together. It still doesn’t look that much like an elevator though.
It’s finally time to to put the skins together. The split ribs get joined with some pull rivets. It’s a tight fit, but the gaps are clearly designed to be big enough to fit the squeezer. The instructions have some hints if the puller can’t quite get enough leverage to make the final pull, but I didn’t have any problems.
Here’s a shot looking back from the trim bracket on the left elevator:
Next up is riveting the rear spar using the “special” bucking bar. The instructions tell you how to fabricate one, but I bought mine a couple months ago when it became clear that I would need one (from reading other people’s empennage blogs). I was really worried that it would be hard to use, but in fact it worked great! Do remember to shim as indicated. It took a little positioning to get the bar stable, but I found it pretty easy to make sure that the bar was pushing up the correct rivet. I hit it with a short burst to get it partially set, then I could lean more aggressively on the bar.
Not too shabby!
I used my 4″ thin nose yoke to squeeze the rivets for the front spar. It was just enough to reach around the leading edge and made quick work of this task. My back rivet bar worked really well to hold everything in place (the instructions ask you to used a weighted bar to hold the work flat here).
The shear clips and other final bits also get riveted here. My tungsten bucking bar (with a lot of tape wrappings) fit in here perfectly.
The next steps are all part of the final close-out. The root and tip ribs get riveted into place. Here, I just hung the elevator over the end of the table and hit both sides with the squeezer.
These two that bound the skins with the end of the counterbalance skin were a real pain. I did not read the instructions closely here and I could have substituted pull rivets. It would have been much easier. I managed to drive these rivets by slipping my tungsten bucking bar into the unclosed end and holding it through a lightening hole. Pull rivets (at least on the bottom) would have been a better call. They came out OK though.
Finally, we finish closing out the rest of the easy rivets. There are still a few open ones getting ready for installing the trailing edges.
The first problem to deal with was a stuck die. This flat die was impossibly stuck in my pneumatic squeezer. I tried just about everything to get it out. WD-40, a vice, pliers… I just could not get it to loosen. Finally, I put a grinding wheel back into my bench grinder and polished off a couple of square ends. Finally, I was able to get a grip on the thing and pull it out. I probably spent an hour on this. Sigh.
With that done, I could finally get the last of the rivets on the front spar on the right elevator. It almost looks done! (but still lots to go)
Time to prep the trim tab. If you remember, I left it incomplete so I could ProSeal all of the ribs in one batch. The first step is to tape and rivet the trailing edge. Unlike the elevators, you rivet the trailing edge first and then slip the foam ribs above the spar.
I used the recommended super sticky tape this time instead of epoxy or ProSeal. If I had read the instructions more carefully, I would have put the tape on the trailing edge instead of the skin. This worked fine, but it was more of a hassle trying to pull the tape over the dimples.
I clecoed the trailing edge into the aluminum angle that I used for the rudder trailing edge (same spacing) to get everything lined up and bonded. Then I broke out the back rivet bar and did the double flush trick. It came out very clean. At this point, the tab is ready for the ribs, so I set it aside. You need to do all the ribs and riveting in one go and then set it aside for a few days, so I wanted to have it all prepped for the next step.
The last step before gluing the ribs in the elevators is to add the double sided tape to the trailing edges and cleco. Then set everything aside for a couple of days to help the tape stick better. My plan was to come back one night in a couple of days and do the nasty gluing step. So, with everything clecoed in place and with the small ProSeal containers out, I let the tape set up.
I came home from work and hurried over to the shop to glue in the ribs for a rare weeknight build session. In retrospect, I should have eaten dinner. I figured this would take a couple hours max and then I would have a late dinner with my wife and son. This is not how it went.
I wanted to have everything as ready to go as I could. I got all the ribs out and placed near where they were to go and the rivets for the trim tab (the trailing edge is riveted after the ProSeal sets). I wore 3 pairs of gloves so I could pull off a set if they became fouled with ProSeal.
I mixed up my first batch of ProSeal. It was pretty nasty smelling. This was the small 1oz package. It sets up faster than the normal sealant, but the garage was cool, so it wasn’t a problem. I had purchased two of them (good call) because I wasn’t sure how far an ounce would go. You add the pre-measured catalyst packet to the base and mix until it is a uniform grey. It smells pretty nasty and sticks to everything. The trim tab ribs went in pretty easily. You need to push hard enough to get them to seat, but the thin layer of sealant lubricates it enough to slide pretty easily. Then rivet the hinge to the spar and pull some rivets on the sides and you’re done — right? Not so fast. I didn’t have the pressure set well in my squeezer and had a hard time getting the rivets set (I pulled off my first set of gloves to get this done). Then I went to pull the rivets for the close out tabs. I pulled the first side and then one in the second side when I noticed that I put the bottom tab on the outside instead of the inside! At this point my wife calls to ask if I’m headed home for dinner. I brusquely tell her to go without me as I’ll be fixing my screw-up! I had to drill out a couple of rivets on the spar and all of the pull rivets. One spun instead of drilled and it was pretty hard to drill out, but I got it (A couple weeks later, when I picked up the trim tab, I could hear the drilled out end of the rivet rattling around inside! Luckily it fell out the small drain gap near the trailing edge. I really didn’t want to open it again!).
Eventually, I got the whole thing open enough to reset the close out tabs and put it all back together.
Then I just added a board and some barbells to hold it flat while the sealant cured.
I hurried to get to the next step before the sealant hardened (remember, I was using the quick setting variant). You peel off the tape backing and hold the trailing edge open (this is why you don’t rivet quite all of the rivets to the root and tip ribs). I used some pieces of 2×4 and 2×3 to hold it open.
You can see how the rib (in the picture to the left above) sort of floats in the middle. You slide the rib into the rear spar with a satisfying crunch that lets you know that it is in place. If you don’t push it in enough, then the tip will interfere with the trailing edge. Once the ribs were in place, I pulled out the wood blocks and clecoed everything. I weighted the connection as called for (I used my back rivet plate, my vice, some of the lead counterweights, some barbells, pretty much anything heavy that I had laying around the house and garage).
The right elevator went much the same as the first. I needed to mix up the second 1 ounce sealant package as the first was (1) running out and (2) hardening too fast. Same deal with clecos and weights. Finally, at about 9:20pm, it was all done. The instructions say to let it go at least 3 days to cure. It worked out to be a couple of weeks before I actually got around to riveting the trailing edges (though now our home garage looks really nice with a new coat of paint!).
I didn’t get much done today. I was ready to double flush rivet the two trailing edges on the elevators, but my back rivet set jammed. The little sliding collar just stopped sliding. I tried lubricating it and sliding it by hand to get it unstuck, but a metal chip or something is preventing it from sliding freely. So I gave up for the weekend, went home and painted the garage to help with marital harmony (and placed an order with Cleaveland Tools!).
I actually needed some other tools as well. I got a couple of new #30 and #40 reamers, some new pin punches (the old ones were cheap and bent a little), and some safety wire pliers (and safety wire!), and a new 1/8″ acrylic drill bit (plastic bits have a very sharp point. Very nice for starting a centered hole for rivet removal. I dropped my drill with the old one and bent it).
I finally double-flush riveted the two trailing edges on the elevator. The left side came out so-so. I removed a couple of the worst offending rivets and tried again. Now it’s OK. The right side came out pretty bad. The heads are not sitting very flush at all. I’m nearly out of 3-4.5 rivets (I ordered some more), so I’ll give it another try later. It’s probably acceptable, but I want to do better as it’s a very visible rivet line.
Proceeding for now anyway. The next step is to bend the hinge pin for the trim tab. You need to make two very square bends. I noted that a number of people have trouble with this task. Pliers are notoriously bad for this sort of thing and can really bugger up the pin. Luckily! I have an 18″ Little Giant Bending Brake (yet another aircraft construction tool I picked up from my Father-In-Law. Thanks Dad!). It took a bit of mental work to figure out how to orient everything, but it is, in fact, quite simple to use.
I cut an 18″ piece of angle bracket to fit the brake (Dad left me a clamp piece with angled edges, but I wanted something square for this step). I put a groove in the bottom perpendicular to the edge to hold the hinge pin straight. I had a Sharpie mark where I wanted the bend to go, but I didn’t have a good feel for how much allowance to make so I left it a little long. The bend was very easy. The mechanical advantage of even a small break made it a snap to get a clean bend. It sprung back a little, so I re-clamped and bent it using the angle piece my father-in-law provided (you can see it in the picture below). It hit pretty close to a 90 degree bend. Then I measured for the second bend and did it again. It looks just like in the plans! I used a grinding wheel to get the final length right to .8 inches. I then cut the long length and ground it smoothed. I made the tip into a bit of a bullet shape to help with the next step.
Then I had to slide the hinge pin into the hinge. It’s a 32″ push! The bullet nose helped. I ran the pin through each individual side to make sure the hinge eyes lined up. I had two that I had to make a slight adjustment to. It took a couple of tries to get it through the whole hinge. I used some Boelube on the tip and some WD-40 along the pin shaft to help it along. It wasn’t as hard as I thought it would be. For the final step, I had to add some safety wire to hold the pin in place. You drill a small hole and then just wire it in place. I watched a couple of You-tube videos to get a handle on how to use the pliers and went for it. The pliers are really interesting. They clamp on the wire and then spin freely when you pull a knob on the bottom. This makes some very nice, tight turns. I clipped the twisted wire off and bent it over to prevent snags.
In the end, it came out really nice and looks just like the picture in the plans.
The next step was to mount the trim tab motor to its bracket. I got the final 3 aluminum parts out for the elevator and deburred and primed them. I also had to dig out the right wiring harness and a molex connector. It all went together really quickly. Only a couple of hitches.
The trim tab push rod is too short. This wasn’t anything I did, the actual part is too short! I got a service bulletin saying that Vans would send me a new one. It is coming with the wing kit in a couple of weeks. I was planning on rebuilding it anyway because I didn’t think it provided enough clearance to swing freely on the trim arm.
The mounting plate is dimpled (for the screws of course), but the backing plate is not! I went back through the instructions, but I did not see any mention of dimpling. I may have to countersink the backing plate or just widen the holes enough to take the mounting plate. None of my yokes fit into the holes. The lore says to think ahead about how each hole is used and prep it accordingly because sometimes the instructions overlook something. This is a case of that I suppose!
So here’s the final view of the elevator. Just need to roll the edges and take care of a few small tasks before it is on to the rear fuselage!
The final steps for the elevators are:
- figure out how to dimple the backing plate for the trim tab motor plate
- roll the leading edges
- wait for the new, longer trim tab pushrod to arrive (Vans Service Bulletin)
- hang ’em on the trophy wall until it is time to attach them to the rear fuselage