Chapter 20 - Winglets & Rudders
Start: 10/13/07
Finish: 03/17/08
Total Time: 77 Hours

Things are really starting to take shape now. This chapter will have us build the last of the control surfaces. As this project keeps growing in size, our garage is getting more and more cramped. Fortunately we've managed to get a hangar at St. Cloud, where we will base this aircraft when it's complete. Until that point we'll store some of the bigger pieces at the hangar. As yet, though, we still have everything in the garage. Can't take the wings up there until we have the winglets attached. Can't take the spar up there just yet, as we're waiting for our spot facing tools to be sharpened so we can bore the wing attach holes. Soon though, we'll be able to free up a good amount of space in the garage.

We start this chapter off by gathering up all the big leftover foam blocks from the wing, which are used to make the winglet cores. We cut the upper and lower winglet, both right and left in one afternoon, and assembled the blocks with micro. Careful attention must be paid to which side the undercamber faces, the mailing list archives are full of info about it, and sadly a few stories of those who didn't get so lucky on their first attempt. Our cores came out very nice, our excitement continues to build along with aircraft.

After the micro cured we made the top cap for the upper winglets and rounded the lower winglets per plans. Next we glassed the inboard side of the upper and lower winglets. Once cured, we flipped the winglets over, installed the COM antennas, and glassed the outboard side.

We turned our attention back to the wings for a bit to finish the control system components in the wing roots, and then proceeded to begin attaching the left winglet to the left wing. This starts by trimming the bottom of the upper winglet. The plans have you use a coping saw for this task, which didn't work well for us. It lead to the worst mishap we've had in a while. It was difficult to keep the coping saw perfectly perpendicular to the cut line. Worse yet, the saw cut more than intended at the worst possible time, accidentally severing the cable for the COM antenna. Repairing the cable was tricky. We had to carve out a bunch of foam surrounding the cable, attach male BNC connectors to each end of the severed cable, connecting them with a barrel connector.

After jigging the winglet into place on the end of the wing, we carve out foam at the mating edges, and lay up bid around the corner. The corners are then filled with foam and flox to keep the glass free of air bubbles. A spacer block is then formed to fit the space between the wing and winglet, and an additional layup is applied on the outside of the mating corners. The foam block is then attached over the top of the layup.

Yet another multi month pause in progress. A 10 week pause beginning in November of '07 started due to work travels, then holiday travels, and ultimately I spent most of January scratching my head trying to determine how to install the hidden rudder bellhorns. Fresh off my incident with the COM antenna cable, my confidence was a bit low, and trying to figure out the proper positioning and angle of the bellhorns had me severely questioning if I was in over my head. Christine was trying to get me motivated, but recognized that I needed to resolve the rudder bellhorn puzzle on my own in order to restore my confidence. In the end I turned to the Cozy Mailing List for help. I explained what I perceived as the issues with installing the bellhorns and how I thought it might be handled. In response I learned angle I was fretting about (caused by the canted winglet) really wasn't as much of an issue as I was making it out to be. I simply needed to make sure the tip of the bellhorn ended up in line with the rudder conduit, when the rudder was fully deployed. As is so well put on Wayne Hicks' write up of the installation, one really just needs to get busy doing it.

After glassing the bellhorn into place, and making the spacers for the hollow area the bellhorn will travel through, we proceeded to carve the big foam spacer between the upper winglet and the lower winglet. Once that was complete, we laid up the 7 ply layups on the outboard and inboard sides of the upper winglet to wing attachment. In the plans Nat cautions not to add additional plies to these layups as they exceed requirements already. Admittedly, the winglet attach seemed VERY solid after these layups cured.

The next step was to attach the lower winglet. This is accomplished by trimming the lower winglet to position it at W.L. 18.4" and then micro it into place and lay up the sides with 1 layer of 2" wide BID at the seams. While I realize the lower winglets are not a high stress area, this layup schedule just simply didn't give me a warm feeling. I widened the BID to 4" and used 2 plies. When complete this definitely seemed like a solid connection.

Next the rudder dimensions are drawn out on the inboard and outboard side of the winglet, and one carefully cuts through the skin on both sides. You then slip a hacksaw blade in the cut line, and saw through the foam to remove the rudder from the winglet. Foam is carved out of the ends of the rudder as well as the cutout area of the winglet, and reinforcing glass is laid up in these channels to prepare for the hinge attachment.

To attach the rudders back to the winglets with the hinges, we start by lining up the hinges in a straight line on the winglet. We then clamped them in place using little c-clamps to hold them while we drilled the holes for the click bonds. We are using click-bonds instead of screws and rivets, just as on the ailerons. This is to allow for a completely smooth surface with no screw or rivet heads. Once all the holes are drilled in the winglet, we recess the head of the click bond in a thin bed of flox on the surface, and nut the hinges in place to hold everything. A layer of BID is then glassed over the top of the click bond.

After the winglet hinge attached has cured we handle the rudder side. We first made little foam wedges to hold the hinge tight up against the inside surface of the rudder. Then we placed the rudder back into the winglet, and form the inboard side we slid the hinges up against the inside surface, using our foam spacers to hold them tightly in place. Then while holding the rudder perfectly in line, we drilled the holes through the rudder skin and hinge. We then removed the hinges from the winglet side, and repeated the click bond installation process on the rudder side. When cured, we can attach the winglet side of the hinges back into place with the rudder.

The last step is to install the rudder return spring. This consists of a 1" diameter aluminum tube, with a plug on one end and a spring attached to the plug, being embedded into the winglet. A small hook is embedded into the forward face of the rudder, to which the other end of the spring is attached.

Now the whole process is repeated for the other winglet. This time we just need to be a little more careful around the COM antenna cable.