Chapter 20:     Winglets & Rudders                                                                                Next  Previous  Home

In this chapter we build and install the winglets , install the comm antennas, cut out the rudders and reinstall them with their hinges and hidden bell-horn gizmo.

Nothing new here! As we say, been there done that! The trailing edge is done just like the canard and wings, I use an aluminum extrusion and clothes pins to get a nice straight edge. I also temporarily installed the lower winglet and glassed it with the upper winglet just to save a little time. I cut it off with the Fien after cure.

After the winglets cured I had the radio tech at work check the antennas to make sure they were centered in the middle of the band. They were  well centered  and broad banded enough to cover the band, thats good!  Interesting,  we had to stay well clear of the winglet or  the trace went wild. Everytime we walked near them the pattern changed. We also taped the hinges  into position to see if there was any change, there wasn't.




Here is what the wing end looks like after you trim it for winglet installation. Takes a little nerve to cut the wing after all it took to get to this point!

    Here is the winglet set as accuretly as I can get it! Nat specifies within .050" measured over 108" with a tape measure? Ok well this is as good as I can get it without getting Lockheed involved.  Furthermore he doesn't specify where to measure the trailing edge, that is, it's .050" thick, do you measure the inside outside or down the middle??
    The sharpened stir sticks tip works good for supporting the winglet during this step, you can't see them but that is what the winglet is sitting on here. That and my step ladder with clamps were used to hold things while the bondo cured. Go ahead and make a little square from a stir stick and put a nail in it to serve as your  "WPRP". Bondo it in place. This will make a much more secure reference point to make these measurments from.

Here you see the process of making the inside lay-ups.  DEEP (2" ) pockets are made for the 4"X12" 8 ply layup (#1) that goes inside the wing skin. The real challenge here is getting the micro sanded off all the way back inside the pockets, that took a little doing!  Next foam wedges are floxed in to hold the glass  down for cure and to fill the void. The last shot is lay-up #2, that one is also 8 ply but an easy lay-up. If you are doing the hidden bell horns, the glass stops at the conduit.
Some of that will get trimmed later.

So the next step is to make a foam transition piece for lay-up # 3, looks simple enough right? Well there is a pitfall here if your not paying close attention. The plans call for the foam to be flat, what they mean is for each UND fiber to have it's own flat surface to lay on. There is not "flat" anywhere on this piece except in a line parrallel to the direction you sanded against. Confused?  Look at the pics above. In the first pic I was admiriming what a good job I had done. The foam is flat, no? Well guess what, I discovered as I began to lay UND down that I had a concave surface under the glass! Not Good!
What happened? The UND fibers as placed were not in direct alignment with the angle the foam was sanded to! So start over, this time I paid close attention to the angle the fibers were going to run and sanded at that same angle.


This time I used PVC foam ( I hate Urethane!)  And I drew the angle the UND  fibers will run on the foam as a guide for contouring the foam. You may note the fibers run at a slight angle to the  spar cap.   That is what threw me the first time, I assumed the  UND would run straight down the wing  and forgot the winglet runs off at an angle to the wing. The fibers must be straight so I used the leading edge of the winglet as a guide this time and my fibers are parrallel to that.
Next step is the "Hidden Bell-horn " installation. This one had me scratching my head a little. I finally made a cardboard "hinge" and glued it to the winglet, set a tooth pic into the foam at the imaginary pivot point, and stared at it for about two days until I understood exactly what is happening here. You can't see it in the pics but the horn must be set at 2 different angles so it ends up parrallel to and at the same elevation as the rudder conduit. This takes a little abstract thinking, but if you stare at it long enough it will come to you. Use the force Luke! Reading Wayne Hicks memoirs wouldn't hurt either.

More coming soon...4/17/07

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