I’ve put in quite a few hours on the tail cone since my last update. We also went to Airventure for the first time and that gave me a ton of motivation to work on the plane.
One of the first things I had to do when I started working on it again was to mark all of the stiffeners with lines that are used to line them up with holes on the tail cone skins to match drill them. Each stiffener gets a line near each end that is perpendicular to the direction of the stiffener. Those are easy to do since they are short lines. You also have to draw a line down the entire length of the stiffener that is 5/16″ away from the edge. This could have been really tough if I hadn’t already seen other builder logs where they made a little tool for marking the line at the proper distance. I think some have used a scrap piece of the J-channel stiffener but I used a small piece of a hinge that I had leftover after trimming the trim tab hinges down to size. There’s a couple holes in it because I needed 2 tries to get the hole drilled in the perfect spot, but it worked really well. I just put it right on the flat side of the stiffener and braced the eyelets against the edge to hold it in the right position, then stuck a marker in the hole and drew the line across the entire stiffener all at once. It made this task so much easier, quicker, and more accurate than it could have been.
After that was done I did some quick deburring on the bottom and right tail cone skins and then got to work clecoing things together and getting the stiffeners lined up. You start by clecoing some frames to the bottom skin and then slide in a few stiffeners using the lines you drew to properly position the stiffeners. Then it’s time to start match drilling the skin holes into the stiffeners. The bottom skin went fairly quickly because it was easy to reach around and re-position the stiffener if it wasn’t quite lined up where I wanted it to be.
Once you’re done with the stiffeners on the bottom, you slide the assembly to the edge of your saw horses and cleco on the right skin. Slide in the stiffeners and continue match drilling. This was more difficult though because, for two of the stiffeners, my arms aren’t long enough to reach under and into the tail cone to re-position them if they aren’t lining up the way I want them to. This meant I had to constantly get up from my stool, go around to the other side and do my best to position them where they needed to be without actually seeing if it was lining up on the other side, and then try to hold it in place with some gorilla tape while I went back around to drill it. Sometimes I had to go back around and shift the stiffener multiple times before I was happy with where it was. Drilling one full stiffener on the right side took me about an hour and forty five minutes total. Eventually though you do finish and get to flip it over to put the left skin on and match drill the stiffeners on that side.
I haven’t been able to put the left skin on yet though because there are a couple frame pieces that go in at the very end of the tail first. I was working on match drilling an angle piece that I had to fabricate with one of those frames and make a really bad hole because I didn’t have everything properly secured. It probably would have been fine to use either the way it was or with a little fix built in, but I did almost the exact same thing on the next hole I drilled. This was enough for me to decide to just replace it. While I wait for those parts I’ve just been working on other small pieces on the tail cone that I can do without needing the tail cone to have the left skin on it. Still, it is really exciting having such a big part partially assembled in the workshop! When I actually start riveting it all together I’m going to have to do it in the garage because the tail cone won’t fit through the door to the work shop.
I’ve put about 14 more hours into the tail cone since my last tail cone post but I don’t really have any photos to show for it. Since then I’ve rebuilt the tie down block and match drilled it to its bulkhead. I actually did end up ordering a different tap off Amazon which allowed me to tap the hole a little bit farther. I also ordered the tie down eye bolts to make sure I was doing a good job tapping the hole and I was a little concerned about how much wiggle room the bolt had. I did some research on the forums and asked around and it seems like this is pretty normal so I’m not going to worry about it.
I spent a ton of time deburring (more like trying to polish with a tiny file) the little flange relief cuts which I think has finally driven me crazy enough to stop. I asked another builder how much time he spent deburring those spots and he said not much at all. So I think from now on all I’m going to do with those is make sure they don’t have any notches from the tools that were used to cut them out at the factory, and remove any burs that might scratch other parts.
I’ve cut a few angle pieces down to size and deburred them and I’ve also cut the long J-channel stiffeners down to size and have started deburring them. At the end of those stiffeners you have to cut them at a 45 degree angle. As far as I can tell this is just to provide clearance around the bulkheads that they connect to at those ends so I didn’t worry about being too precise with them. I set the miter gauge on my band saw to 45 degrees and just kind of eyeballed it. I’ve held a couple up to the bulkheads they will attach to and I think they will work out just fine. If I need to trim them down a little more later then it won’t be too much trouble to do.
And here is the only photo I have from all those hours of work. This is after I cut them down to the proper lengths but before I put the 45 degree cut on the ends.
I’m a little late in writing this post, but on 7/8/18 I finally finished the elevators! Well, they’re finished for now anyway. They still need safety wire to hold the trim tab hinge pin on and the fairings installed but those will come at a later step.
When it came time to roll the leading edges, I was a little concerned because of the different sections and the way they were positioned on the elevator. With the rudder, I just used a long PVC pipe and let it extend past the end of the elevator and rolled it from there. With the tip rib on one end of the elevator and the elevator horn on the other end this wasn’t really an option. I did some searching on the forums and found this tool here: http://www.vansairforce.com/community/showthread.php?t=126571
Basically, you get a closet rod that is 1.25″ in diameter and a couple 7/8″ sockets and you JB Weld them into the ends of the closet rod. Then you can just attach a socket wrench at either end and crank away on that to roll the edges. It worked really well and was actually pretty easy to make. I cut the closet rod down to 26.5″ which was the perfect size to be able to do the small outermost section of the skin, then the middle section, and then the innermost section without it bumping into any other rolled skins or the horns.
I was wondering if cutting the lead counterweights was going to be a problem because another builder told me that he ruined his band saw blade attempting to cut his. So I started with my hack saw and I quickly decided that it was going to be too much work to do it that way so I decided to give the band saw a try and if it ruined the blade then oh well. Luckily it worked really well and the blade still seems nice and sharp and not loaded with lead. It didn’t cut very fast through the lead though so I did have to be careful about the weights getting too hot to hold. In the end, I didn’t do a perfect job cutting them down to size and even had to do a little trimming to get them to clear some rivet heads when I was bolting them on to the elevators, but I think they will be fine.
Oh, also before I did any of the things I just wrote about, I had to finish the rivets close to the trailing edge of the tip rib on each of the elevators. These rivets are in a really narrow spot and I hate it when I have to set rivets like this. Probably the only way to set these rivets is to do kind of a modified back rivet. You set the part on your back rivet plate with the rivet in the hole, and then you have to place something on top of the rivet that will stick out far enough for you to hit with the rivet gun. Even though other builders make this look pretty easy, I’ve never had much luck with it. I’ve tried the flat side of a screw driver, I bought a crow bar thinking the end of that would be narrow enough to get in there but I wasn’t happy with that either. After watching a Hints For Homebuilders video on the EAA website I went out and bought a 2″x3/16″ steel bar. I cut a short section off of it, trimmed the corners off to make it narrower on one end, and then ground it down on one side to make it thinner at that narrow end I just made. This only kind of worked. Maybe I didn’t have my rivet gun set to a high enough pressure but the rivets took one heck of a beating and didn’t fully set. Luckily it was able to set them enough that I was able to get my thin nose squeezer in there to finish them off. Here is what the tool looked like:
I saw Justin do this on his blog and couldn’t wait until I could do the same thing with my elevators 🙂
I put in a few hours over the weekend and managed to get the trim tab hinges match drilled to the elevators and trim tabs and then got everything riveted together. Since I’ve been priming everything so far, I usually don’t get to drill, debur, and then rivet parts together all on the same day so this was really satisfying progress.
I officially started the tailcone on May 22nd! At this point I’ve put in 12.4 hours of work on it. You start off with trimming down the tie down block to the proper size and tap the hole using a 3/8 x 16 tap to a depth of 1 1/4″. Trimming the block down went well and tapping it wasn’t too hard but I was concerned about the depth of the tap that I was using. It only let me go about an inch deep so I looked around for one that would let me cut the treads a little farther into the hole but haven’t been able to find one. I ended up messing with this tie down block so much that I messed up the threads in it and I’m going to order a replacement and try it again.
I did learn though that the eye bolt that is used to tie down the airplane is supposed to have a nut on it as seen here:
Looking at 3/8″ nuts at Home Depot I’m confident that this will only allow the eye bolt to screw into the hole about 1″ so I don’t think the hole really needs to be tapped to the full 1 1/4″ depth. So, when I get my replacement aex block, I’m just going to use the tap I already have and not worry about it again until it becomes a problem.
Since I didn’t want to keep working on those parts while I waited on the replacement, I skipped ahead a couple pages and started working on the F-1010 bulkhead.
There’s a piece of aluminum angle that is on the other side of the bulkhead that I had to trim down to size, clamp in place, and then match drill all of the holes along the top of the bulkhead (which is at the left side of the picture).
After that I spent a lot of time deburring bulkhead parts, assembling them, and final drilling them together.
And finally I marked a bunch of J-channel stiffeners to lengths that they need to be trimmed to but I have not cut them yet.
I’m really excited to be working on the tailcone finally. I’ve heard that it goes together pretty quickly so I’m hoping that I’ll soon have it assembled on a couple saw horses in my garage.
Meggin and I got all of the foam wedges and the trailing edge wedges glued into the trim tabs and elevators. I thought maybe the Proseal would be easier to work with this time around since the weather was warmer than the first time we used it for the rudder trailing edge but it didn’t seem to make much of a difference. It was nice knowing what to expect this time around though and using Proseal that had a longer working time than what we used on the rudder helped take some of the pressure off. We used popsicle sticks to spread the sealant onto the foam wedges in a thin layer and we used a small foam roller to spread the sealant onto the trailing edge wedges. Once everything was clecoed together and weighted down I let it all sit for a week.
After the week was up, I riveted the trailing edges of the elevators and did most of the last of the rivets going down the outer most rib towards the trailing edge. I had to stop though because I didn’t have anything thin enough to get into the narrow end of the trailing edge to set the last rivets.
The trailing edges turned out nice and straight. There is a little separation of the skins on one of the elevators. Maybe I didn’t put a good enough edge break in it before I glued them together and riveted them. It’s not that bad though so I’m not going to worry about it.
I’ve put about 50 hours of work in since my last post so I figured it was time to update the blog. Work has slowed down a bit recently because Meggin and I adopted a puppy and we’ve been giving her tons of attention, but I’m starting to get back into a good routine of working on the plane.
Since my last post, I have back riveted the elevator stiffeners to the elevator skins
While doing the very last rivet on the very last stiffener, I let the rivet set slip off the rivet and dent the skin a tiny bit. Of course, the dent is on the top skin of the elevator instead of the bottom where no one will see it. It’s not too bad though.
I riveted the stiffener halves together to join the elevator skins. This was a little tough since there isn’t a lot of space between the skins to get your hands into but otherwise it was uneventful.
Then I riveted the spar to the stiffeners and the skins.
Riveting the tip ribs to the elevators requires setting some rivets in a really tight spot. I checked other builder blogs and no one else seemed to have any trouble with these rivets but I had a terrible time with them. I could not prevent them from bending over. I drilled out at least 3 rivets before I found out from Van’s that blind rivets were an acceptable replacement for the solid rivets here. Unfortunately though, I did a terrible job of drilling out the first rivet I set and enlarged the hole quite a bit. I ended up having to use a larger rivet for this hole, and because the larger hole no longer had the correct distance from the edge of the flange it is located on, I had to build doubler plates for both sides of the hole and add a couple extra rivets to the flange. I don’t think the hole looks too bad in this picture but in the horizontal direction it is large enough for a 5/32″ rivet even though it is supposed to use a 4/32″.
Then I was ready to give the trim tabs another attempt. This time I used Scotch brand double sided tape and cut new blocks for clamping the skins down. I found that by setting my table saw to about a 10.5 degree cut, I was able to cut out a wedge that matched the angle of the trim tab almost perfectly. Everything went well at first. I bent the outboard tabs of the trim tabs without any trouble. However, when I started to bend the inboard ends the wedges were sliding as I clamped them down. My best guess is that the leftover glue from the tape I had been applying, removing, and reapplying every time I moved blocks was preventing the new tape from holding properly. So, the bottom block slid out of the trim tab and the upper block slid down which resulted in another dent near the trailing edge of the trim tab skin. Luckily I planned ahead for something like this to happen and put the top of the skin against the table so the dent is on the bottom of the trim tab. I don’t want order more trim tab skins unless I really have to so I’m going to build on for now. When I did the second skin I added another clamp to prevent the inner block from sliding out, but the upper block still slid down so I ended up with a less severe dent in the second trim tab. You can see the smaller C-clamp that I added in the second picture below.
That brings me up to where I’m at now. Last night I added the bend to the bottom flange of the trim tab skin and reassembled the trim tabs so that they are ready to be final drilled next time I work on them. I’m hoping that over the weekend I’ll be able to get the foam ribs and trailing edge wedge glued into the trim tabs and elevators with Proseal.