The second most asked question, right behind “How long until you’re flying?”, is “Have you started the wings yet?” As of 10/17/12, I can answer YES! I drug all the foam out of the basement, took some measurements, and glued them all together using “Great Stuff” expandable foam (red & yellow can). Per Dennis Oelmann, spray it on the edge of one side, making an “S” pattern all the way to the end, keeping about 1.5″ of open foam between. Set the connecting piece on top and move it back and forth to collapse the spray foam and get a nice even coating. Make sure the foam is aligned correctly and add weight and nails to keep from moving. Note that you want to use a lot of weight. Even though the foam looks like it is done expanding, it has really only slowed down. Lots of weight will keep a tight joint for happier hot wire cutting. As it turned out, I had used a full can for one wing, where Dennis can get both wings out of one can. They still turned out great, regardless.
Dennis showed up to cut out the wing cores. We started by cutting the blocks to the correct angle and size. Added scrap where the plans say to add scrap to prepare to cut the cores. Cut the cores out using the templates. Dennis has done this so many times, he can pretty much do it in his sleep. He told me he has completed 67 sets of wings, so I’m certainly not questioning any of his methods. It was an all day event, but they turned out great! Micro’d all the loose pieces on the inboard right wing to glue them together. Added nails, weighted, and let cure overnight.
Glued the right wing cores together, being sure to align everything as perfectly as possible. The inboard section had to be raised about 1/4″ in the jig to match up the angle. Dennis said that is pretty common, so I proceeded with gluing the cores with micro. Secured with nails. The joint between the center and outboard cores was off slightly, so I will need to sand flush.
Marked the cutouts on the wings for LSA4 positions. Then marked for inserting the LWA6 and cut out. Used a hole saw at the bottom, and cut up to the shear web from there, being sure to leave a lip for the LWA4’s to rest on. After cutting the recess for the LWA4’s, I cut out the recess for LWA6. Started cutting the W18 pieces, but need a little practice to get the bends right. Start by cutting a strip of 2″ thick aluminum, lay in place, and mark the locations for the bend (it’s not 90 degrees). Bend the piece and trial fit. After verifying the bend is correct, and the piece still covers the hole evenly at the shear web, mark both ends for a flush fit to the skin and shear web. It helps to put the LWA4 in place to accurately measure. I left a bit long, and sanded tor a more precise fit.
Glassed the cutouts with 2 ply BID, after covering with micro and micro corner transitions.
Micro’d in the LWA4’s and the LWA6 into the wing, making sure they were flush with the foam, so there are no humps when the shear web is installed. I then used 5 min epoxy to affix the metal plates in place that cover the hole we made in the spar trough, so we will be able to lay the spar cap tape in the trough and not have it sag in the hole. I then proceeded to cut out all the UND cloth for tomorrow’s layup and cleaned up.
After the hard points have cured, I sanded the corners down to the same curvature as the metal hard points. Then taped newspaper around the spar area to protect the rest of the wing from epoxy. Then sanded in preparation for the shear web layup.
Micro’d the shear web area and started glassing per the plans. Brandon and Kim helped half way in, which helped speed things along immensely! Thanks guys! Added peel ply, and realized I wasn’t quite done. I cut back some of the peel ply around the hard points, and added th required 3 ply BID and epoxied the LWA2 and LWA3 hard points. Added some weight, and added some nails to keep from sliding.
Cut the wing root to be perpendicular to the spar cap trough. Then prepped for the spar cap layup.
Filled the spar cap trough. Took more plies then the plans showed, but it’s filled up now. Added pour foam in the gap between the two leading edge foam cores, and micro’d the aileron access wedge back into the wing. Spent the rest of the time preparing for tomorrows layup of skinning the bottom of the wing. (I seem to be short on pictures of the bottom spar cap, so I attached a picture of the top spar cap, which is more or less identical.)
Dad and David came over to help skin the bottom of the right wing. 2 plies UND at opposing angles. Then the two supporting UND pieces at the wing root (2″ x 4″ and 12″ x 12″), as well as the triangular BID at the wing tip. Was sure to add the peel ply for the wing tips and the aileron cutouts, and a flox corner for the access hole. Covered in peel ply.
Got up at 4am to knife trip the edges and lay micro into the trailing edge, and then back to bed.
Finished cleaning up the knife trim areas with the file and sanded down the micro on the trailing edge to fair it in.
Put the jigs back together, flipped the wing over, checked for straightness and twist, and secured the jigs to the table with angle brackets and screws. Sanded the trough to prepare for glassing, and covered the rest of the wing with plastic. Added the Dams, and it is ready for the spar cap.
Removed the dams and peel ply. Trimmed the ends of the spar tape flush and rounded over the edges of the wing root.
Sanded the wing surfaces smooth and prepped the surface for glassing. I accidentally broke the foam where it was hollowed out for the aileron tube. I was able to use micro and nails to hold it back together. Marked and routed the trough for the rudder cable to sit in.
Added a bead of micro in the trough, minus the last 3″ at the outboard end where the winglet will attach. I also added duct tape to the last 3″ of tubing that lays in the trough, as well as the rest of the tubing, sticking out on the ends, to protect from epoxy. Added nails at an angle over the tubing to hold it in place until after the micro cures.
Dave, Brandon, and Kim helped a lot today, as we skinned the top of the wing. Filled in the top of the conduit trough with dry micro, as well as any gouges in the foam from releasing from the jigs. Also, I used dry micro on the aileron, to ensure a light part. Then we micro’d the whole surface and started applying cloth. Two at angles the same as the bottom, and one additional the length of the wing, which does not go on the aileron at all. Also added the additional plies toward the wing root and wing tip like on the bottom, and added the 3 plies of UND over the inboard hard point. Finished off with peel ply over everything!
Carved out the foam on the outboard wing root with the Dremmel tool attachment to get a consistent depth. Finished by sanding the bumps for a smooth surface. Then I carved out the inboard wing root section. Dennis and I did not carve out the shell when we hot wired, but we did cut off the wedge so we had the flat surface that is 90 degrees to the trailing edge. Then sanded the foam completely out of .7″ of the edges all the way to the skin. Also carved the other parts of the foam as described in the plans, making sure to leave the .7″ above the hard point. In talking to Dennis, it sounds like I got my rudder cable too high, and will need to do some minor surgery. The rudder cable was coming out of the wing edge, which will not work when it comes to attaching the cowl, as it will be in the way. Since I have not glassed the wing ribs yet, surgery will be easier. Only problem is that the micro is pretty thick from gluing in the rudder cable conduit, so I will have to be very careful, as this minor surgery could have some major complications. As it turns out, it was a non-issue, as the micro was easy to trim off.
Glassed the two 3″ pieces of UND that form an “X” around the bolt hole depressions. Then glassed the 3 layers of BID on the inside of the outboard wing root, leaving the third layer extra long to cover the hard points.
Spread micro on the foam, made my transitions in the corners, filled my trough where I dug the rudder cable out, and glassed the inside. Dennis gave me the hint of cutting triangular pieces to cover the inside face and upper and lower surfaces only, then add the forward facing piece separately, and connect with BID tapes. Now for the oaf story… Since I believed this was done this way only because of all the angles and such, I decided to save the section where the rudder cable is coming out for last. Poor judgement on my part, as I wrestled with that first layer forever while the forward facing cloth kept falling on me. (Remember, the leading edge of the wing is pointing at the ceiling in the jigs) Then I decided to lay up layers #2 and 3 on tin foil to transfer to the inside. Good to use the foil, bad to lay them both at the same time. I have had this happen before, and this confirms my thoughts. In order to not get air bubbles, those layers need to be able to move around to form around all the joggles and divots. Not a problem if you put them on one at a time, but wetting two plies and having the epoxy curing while you are working with it, certainly isn’t doing you any favors. Trust me, the time you think you are going to save by laying up multiple layers for these complicated surface features, you will spend again 10 fold fighting bubbles. It is tight in the wing root, though it did help to cut the handle off the paint brush for stippling. After all ply’s were now laid in place, finished with peel ply, and I will check frequently to make sure the air bubbles don’t come back. Added the 3 plies over the hard point LWA6 and clamped LWA7 in place. In hind sight, I just realized I only have 2 layers of the forward facing section of the wing root. I have to add BID over LWA7 after cure anyway, so I will add the extra layer then.