Archive for May, 2009
Getting started on the tailcone
Posted by: | CommentsStarted to match drill and cleco together the bulkheads as well as get the bottom skin ready for the work ahead. Also started making the j-stiffeners. Lastly, I made the tied down block and tapped the hole for the tie down eye bolt.
What to do with the finished parts
Posted by: | CommentsWell, I’ve been tripping over the various assembled pieces of the empennage for four years now and finally decided to do something about it. I have numerous small dents and scratches on the horizontal stab, rudder, elevators, vertical stab, etc from moving the parts around, tripping over them, dropping them, knocking them over, etc (nothing major, just minor scratches and dings) as well as more than a few nicks in my legs from bumping into the edges. I saw Tim’s wing cart and thought, well why not for the empennage parts? So I ran down to Lowe’s Aviation Supply, and got myself a bunch of 10′ 2×4′s, a circular saw, and a couple boxes of nails (see how I snuck a tool in there too? I also grabbed an 8′x10′ under carpet grippy material to use as a liner since it was cheaper than carpet. If you have access to carpet remnants, I would suggest thats a better solution but this stuff worked ok. Lastly, you will probably want some casters so that you can roll it around as a cart. I got 3″ casters with brakes, and one at each corner of the cart seems to work pretty well.
For anyone who wants to play along, the long dimension is 10′, the width is ~21″ and the height is approximatly 36″. I made the center bay wider than the outside bay, but I wish I hadn’t because the stuff that I put there moves around a lot when it is being moved. The bay’s should be between 4 3/4 and 5 inches wide and all the parts will fit just fine. I made two 4 3/4 and one 6 1/2 to accomodate the width of the vertical stab at the base, but it turned out that part isn’t between the uprights anyway.
Well it turned out quite functional, and it’s very easy to move… I can just wheel it outside when I’m working and have it out of the way entirely. I also made the wing cart as well as documented on Larry Rosen’s build log.
If you want specific dimensions, just send me an email (or post a comment) and I’ll send them to you. Oh, and one other note, the cheap 2×4′s at Lowes are cheap for a reason. I left them on the floor of the garage overnight, and when I came back in the morning there was a pool of liquid underneath them… that’s how wet this wood is, so the nails don’t grab well and the wood splits easily. You may not want to be as cheap as I am and grab fir or higher grade 2x4s than I did!
Materials List (this includes enough for both carts):
15 2x4x10′ boards
2 boxes of number 8 nails (You may not need as many, I think I over engineered it)
8 3″ rubber casters
carpet remnants (at least enough for 8 6″ wide by 4′ long strips)
32 1/4″ washers
32 1/4″ x 1″ lag bolts
Hinges
Posted by: | CommentsAlways do your match drilling with the hinge pin in place. I found out the hard way that if you don’t, the hinge pretty much doesn’t come out exactly straight, and then binds as it moves through its range of motion. Even when I used the correct method and did my elevator trim tabs with the hinge pin in place, it still has a little bind to it… not enough to notice while moving the hinge, but it is enough that in certain positions the hinge pin moves freely and in others it can’t be pulled out or put in at all.
The elevators are done… mostly…
Posted by: | CommentsOk, finally got the trim tabs sorted. I’m not really all that happy with them because of having to drill out all of the rivets on the hinge line. That left a few of the holes irregular, so some of the rivets are a little funky. It’s a trim tab though, so I’m not too worried about it, structurally it is still sound and the paint will cover the cosmetic issues. if one of the rivets shows wear at some point I’ll make a new one, otherwise the other twenty some odd rivets should keep it together! Note to self: NEVER try to match drill a hinge with out the hinge pin in place. The plans don’t explicitly (at least on my revision) say to leave the pin in, but they show it in in the drawing. The only things left to do on the elevators are the counter weights, safety wire, and fiberglass tips. One builder suggested leaving the counterweights until final assembly so that you can shave off the extra bits more exactly to get the right weight, so I will. I don’t have a safety wire tool yet, and the fiberglass isn’t going to happen until I’m doing ALL the fiberglass at the same time. Yuck. Pictures tomorrow as the camera battery is dead.
More elevators and a #$%^
Posted by: | CommentsDan came over today to help me finish up the elevators. I had cut, drilled, and deburred the hinges for the trim tabs before he got there… more on that in a second. I had also decided to apply the sanchem 6100 to the outside of the skins of the elevators since I had those patches of corrosion on the one. We spent most of the time yesterday cleaning and applying the corrosion protection. The hinge material didn’t take to the sanchem too well, so I primed those with an etching primer from a spray can. We rolled the leading edge on the left elevator and then drilled and deburred the holes. Once that was all done, we riveted the leading edges on both elevators, and riveted in the hinge halves for the elevator trim.
Now, about the elevator trim hinges. It shows in the manual drilling the hinges with the hinge pin in place on the trim tab while it is attached to the elevator with clecos. The problem I had was that there was no good way to drill the hinge material while it was still attached to the elevator because I couldn’t get behind it to hold it in place (the hinge material is not pre-drilled.) So I lined it all up as best I could and pulled the hinge pin and finished the drilling on the trim tab side. After re-inserting the hinge pin, the hinge is binding on both elevators. @#$%. I checked on the forums and it looks like the only way to fix it is to get a new hinge and drill the old one out, and redo it they way it shows in the manual. Unfortunately, the manual is not explicit on the point that if you try to drill it without the hinge pin in place, you can be off a little bit on some of the holes and the hinge will bind. Visually, none of the holes are even a 64th off, so it’s actually pretty critical that the pin be in place while drilling the trim tabs. I’m going to try to take out the rivets where it is binding and see if I can smooth it out and re-rivet them so that it works, otherwise I’ll be ordering some more hinge. I’ll need that anyway for the rudder trim mod.
Oh, well, the leading edges came out pretty well at least. One is almost perfect, and the other, I forgot to make the bend prior to rolling the skin, so it’s not totally perfect, but its not too bad either.
More elevators
Posted by: | CommentsWell the dyna seal sat for four days, so I figured it was time to get back to it. Riveted the trailing edges on both elevators, and rolled the skins on the left one. I couldn’t find my mk-319-bs rivets so I started on the hinge for the trim tab. I got about halfway through finishing up the left elevator and will work on the right tomorrow, and I’ll probably even get to start the tailcone.
Dynaseal. More fun than sticking your finger in a light socket.
Posted by: | CommentsToday we (Jacob and I) riveted in the spars to the trim tabs, then applied the dyna seal to the trim tab ribs, elevator trailing edge ribs and the trailing edge wedges. Cleco’d it all together and put the clamps on the trim tabs and weight on the elevators to let the dyna seal seat. That stuff is plain nasty, smelly, very gooey and gets everywhere. I forgot to put the light bend in the trailing edge of the right elevator, so that one isn’t going to be as pretty as the other ones, but I didn’t realize it until after the seal was on it. Oh well, I think the only way to fix it would be to build a new elevator and it’s really a cosmetic issue anyway, but I’ll throw a question out to the mailing list anyway. Now it’s gotta sit for three or four days while the sealant sets.
Trim Tabs, Continued
Posted by: | CommentsFinished up the left one and did all the same stuff for the right. The right one went much faster, since I’d had practice already (heh, the right side of the plane will be nicer than the left I think) I also did the first part of the sanchem corrosion protection on the inside of the skin as after I bent the first one, I realized it was going to be tough to scrub the inside. I’m still interested to see how I’m going to do the lower rivets on the spar for these things. Now I just need to finish the corrosion protection on all parts and then it’s on to pro-seal (yuck) the trailing edges of the elevators and the ribs of the trim tabs.
