Cozy

Chapter 19c - Attaching the wings & ailerons

Drilling the holes

I put the main spar in place on the fuselage and rigged the wings in position. For the first time I saw the plane in pretty much full assembly. Wow. This plane is big. I suppose it looks big because you dont expect to walk out onto someones patio and see a four seat plane sitting there. On a ramp it probably looks about the right size. After an hour or so of walking around the plane taking pictures and assimulating the awsome concept that I built this and its gonna fly I got back down to business and layed out the holes on the aft of the spar. One of the inboard holes seems to be about 3/16 off center on the hardpoint, but otherwise everything looks fine.

I tried to jig the right wing and main spar on the bench, but had trouble getting everything level. I could see what the correct position for the mating spar and wing was by eye, but leveling the waterline between the parts was hit and miss because I didnt know where to measure. Sounds simple, but in practice I was getting 0.4 degrees out depending on where I put the level. I didnt trust the measurements I was getting, some of which set the wings so that the spar was at a visible angle to the wing. Obviously the spar needs to be "inside the curve" of the wing so the strake skin can enclose it in a smooth curve, otherwise I'll be sanding away chuncks of spar structure to get a good shape. That can't be right. I'm confident that the wings and spar are very close to the correct shape and size. I decided to try a different approach. I leveled the fuselage, put the spar in place and leveled the spar. Then I jigged both wings up against the spar using foam wedges. This way I could be sure the spar was in its correct position and could check wingtip heights, compare angles visually against the canard etc. The critical issue here is incidence. Since the spar is not fixed yet, all I have to worry about is getting the incidence the same for both wings - and I can even adjust this later using washers. The hard points "want" to mate up and they're all parallel. I ended up doing my hole drilling a bit backwards. I started by getting the hardpoints firmly butted together and the top and bottom of the spar level with the wings making sure the spar was not jutting out either above or below. On the bench I couldn't really see what was going on on the bottom surface, but with the spar on the plane I could easily get underneath with a straight edge and check. Once I had everything so it "looked right", I measured the angles on the wing level bars and made small adjustments to get them the same. I put the 169 and 67.5 templates up against the wings and drew 17.4 WL level lines on the ends of the wings. Finally everything seemed perfect except the incidence - but it was the same on both wings, so all I had to do was rotate the spar in its slot. This agreed with the fact that the spar was a little out from the vertical when compared with the firewall. I bondoed everything in place and drilled the 1/4 holes from the forward face. I've read that the 5/8 centerbore tool is useless for this job, but decided to try it anyway before getting a better hole boring tool per archives. Archives are right. It took me 1/2 hour of very slow going to get part way through one hole. After this my centerbore tool had lost all its points and was just generating heat. I'll get a decent hole bore tool and do this drilling later. I can always put 1/4 bolts through the other two holes to get things back in place while I drill the third hole. I needed to redo one of the reinforcing layups on the right wing and install the LWA 7 aluminum I'd forgetten so I started to dissassemble the "airplane". When I removed the supporting foam blocks from under the left wing it just hung there on the bondo. I put extra weight on it, but it stayed in place. It was kinda neat seeing the wing attached. Hmmm. I wonder if we really need all these bolts? Kidding - just kidding! Finally I had to chip the bondo off with a chisel to remove the left wing.

At Jeff Russell's recommendation I got a Starrett Quickshot 5/8 hole saw from Grainger item # 4L585 for $10. This tool cut through in a couple of minutes and made a nice accurate hole.

Attaching the wings

I'd already drilled 1/4 holes. Now I set the spar in place and checked everything with a water level. I checked the distance to the canard tip at both ends and "adjusted" the cutout in the fuselage until the spar was vertical, level and the same distance from the canard tip on both sides. Then I bondoed the spar temporarily into its permanent position. I'm a bit nervous about floxing the spar in place until I know everything is right. My plan is to do all the final adjustments of dihedral, sweep and incidence with both wings and the spar on the plane, finish off drilling the 5/8 holes, recheck everything, then set the spar with flox. Unfortunately, the weight of both wings broke the bondo and rotated the spar.

One evening I decided that it would be easier to get around the plane if it was pointed into the patio rather than out of it. It took three of us 20 minutes to move everything around. Now the winglets are 2 inches below the patio roof, about 6 inches from the edge of the roof and I have about 2 feet at the front. Getting to the hot tub is a little difficult, but otherwise the plane fits under my patio perfectly. My workbench is still in place and I'll be able to build the canopy and strakes without having to move anything. When it comes to finishing the bottom of the plane we're going to have an interesting time turning it over, but I'll deal with that when I get to it.

I've decided that the best place to store the wings is on the plane. I'll be moving on to the strakes soon and the wings need to be on then anyway.

Ailerons

I layed out the dimensions on the right wing and cut out the aileron. I was admiring how accurate I'd been. The peel ply was just where I expected it to be. Then I noticed that I'd cut the inboard end along the butt line angle when it should have been at right angles to the trailing edge. Now I had a small triangle on the wing which should have been part of the aileron.

Isn't it wonderful how easily you can fix mistakes in fiberglass. I cut the triangle off the wing and stuck it on the aileron. There's a BID layup which goes in the end, so I removed the foam from inside and inserted some flox, then smoothed it off with dry micro ready for the end layup. The end layup will cover the cut along the skin nicely on the inside. I added a 1 BID repair on the outside skin and left the aileron to cure. No one will ever know. The 3 ply (plus an extra ply for the hinges) BID layup inside the aileron recess was a bit messy, but I got it done eventually.

While waiting for delivery of epoxy to attach the winglets, I worked on the two ailerons and one rudder to get all the edges straight and correct and attach the hinges. I got the teflon hinge conversion from Gary Hall. Cost $27. This kit was developed by Gary and Mike Melvill and is supposed to stop wear and corrosion of hinge pins. Had no trouble installing the teflon, but I did make one mistake which might be a problem later. Gary's plans say to pinch the end of the hinge to stop the pin coming out. After doing this I noticed that the Cozy plans say to remove the pin at one point while attaching the aileron. Oops.

I found the aileron measurements a bit confusing. Everything is specified at an angle along the foam joins. At first I mistook these measurements to be at right angles to the TE and the ailerons were too wide. I'd microed the steel bars in place and had to chip them off again to sand the edge of the aileron some more. My aileron skins ended up measuring 7.2 at one end and 5.05 at the other (at right angles to the TE) before adding the steel bar. This gives me the plans sizes when measured at an angle. I checked all the edges for straightness with a long aluminum ruler and sanded the aileron socket hinges to the correct size. When I came to fitting the hinges I found that the screws are tough to turn and I ruined the heads on a couple of them. I was tempted to put them on with hardware store bolts because they have to come off again for painting - then decided that I'd just replace the bolts on the final installation. I messed with the edges and clearances for hours, microed in the steel bars, hinge supports and control tubes, then finally did the layup over the ailerons. I missed some serious bubbles along the edge on one of them and had to sand off the layup and do it again. Finally the big moment came - I put dabs of bondo on the hinges and duct taped the right aileron in place. While waiting for this to cure I started working on the rudder. Since the wing was on my bench I used the wing to suppoer the rudder. I forgot about the aileron bondo and rested the rudder on the aileron. Crash. I scrapped of the part cured bondo and put the aileron back in place. This time I let it cure and then - at last, I was able to wiggle my aileron up and down. Cool. Just need to widen the clearances a little.

Fiddly bits

I thought I was almost done when I glassed the last wing skin. No chance. There are a lot of edges to get straight, holes to drill, and ribs to glass before the ailerons are complete. I worked on the winglets and rudders at the same time. The fiddly bits seem to go on for ever.

Aileron Hinges and fitting

Did you know that each control surface has 12 edges to get line-up and straight? That's 48 edges for all four. The hinges were fairly simple, but seemed to take forever. The plans bondo trick didn't work very well for me. I ended up marking the position left and right and using a straight edge to make sure the hinge was flush with the top. Once I had the hinges in place on the aileron I used 5 min epoxy on the edges to hold them in place while I refitted the ailerons and checked the holes for alignment. Once I had everything right, I pop riveted and floxed the hinges in place per plans. I removed the ailerons and rudders again aand applied some peanut butter type micro as a start to the finishing process.

Finally, after almost 3 months of work, I'm done with the wings and winglets. On to the canopy at last.

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