Wing tip work

 We continued working on the wing tips.  With the fiberglass pieces glued on for the wingtip lights, we then used a few coats of lightweight filler to smooth the joints between these pieces and the wingtips. 

Filler added to smooth transition to the light mounts

We also discovered an issue where the screw attach holes drilled in the wingtips no longer lined up with the holes in the wings.  This appears to have been caused by the fiberglass modification we made to the front of the wingtips.  While this modification was needed to get the leading edge of the wingtip to line up with the leading edge cuff, it also caused their position to shift slightly so the previously drilled holes just didn't work.  We decided that the simplest fix was to fill in these holes and drill new ones, so that's what we did.  We filled them with epoxy/flox combo, let it dry overnight, and then redrilled the holes the next day, using a hole-locator tool to ensure that the new holes in the wingtip lined up with the existing holes in the wings.

New holes drilled, with screws temporarily installed

We also started working on another wingtip modification to close up a large opening at the back which should improve the aerodynamics a bit.  We are using a few pieces of balsa wood to keep it light, and plan to apply epoxy-varnish to them before installation.   Hours: 10.5

Wing Tips and flap gap work

Several updates since the last post:

After priming the right wing, we realized we hadn't fitted the aluminum piece to seal the flap gap for this wing yet, so we cut the aluminum strip to size, measured and matched the rivet hole locations to the left wing, and then drilled the holes.  Final installation of this piece will occur much later in the build process.

Next we turned our attention to the fiberglass wing tips.  Because we added a leading edge cuff to the wings, the profile of the fiberglass wing tips did not match the profile of our wings, so we needed to do some fiberglass work to get them to look right  (nothing like learning a new skill).  

Leading edge of wing tip did not line up with wing

 We used some pink foam and lightweight filler to carefully form the shape, and applied a layer of epoxy with micro-beads to fill in any small cavities.  We then fiberglassed over the shape with alternating layers of fiberglass and epoxy. After this dried, we applied another thin layer of epoxy with micro-beads to fill small voids, followed by another light epoxy coat.  Once this was done, we applied some more lightweight filler to smooth everything out and sanded it.  This took a bit of time, more so because this was a new skill, but we're happy with the way it came out.

Adding foam to wing tip prior to fiberglass

Wing tip profile modification completed

There was another modification that we still want to do the wing tips, which was to add additional fiberglass pieces for mounting wing tip lights. We purchased these parts, so at least we didn't have to make them ourselves.. but we did need to install them.  We  first cut some holes in the wing tips that will allow us to pass cables through to the lights, and also help to lighten up the pieces a little bit.

Nice big hole cut in fiberglass wingtip

Then we did a little sanding prep work (including slightly beveling the edges of the fiberglass pieces), and glued them in place with Hysol epoxy, then added a bit of weight on top to helps hold them in place while the adhesive cures.  Hours: 15

Fiberglass mount for lights glued in place