Step 7.4, Wing tip lens

At night and at some distance, it can sometimes be difficult to readily determine if an aircraft is coming at you or going away.  For this reason, it is required to have position lights on your aircraft if you want to fly at night.  Position lights are red on the left side of the plane and green on the right.  In addition to the position lights, most aircraft also have strobe lights on the wing tips and/or tail to enhance visibility.

On the RV, the position and strobe lights are mounted within a recess on the wing tips.  The recess is covered with a clear plastic lens that comes with the kit.

The first thing you notice with the lens is that it is a single piece of vacuum formed Plexiglas that must be cut in half for the two wing tips.

And so the lens is pictured above after the first cut to separate the halves. The next challenge is deciding where to start the fitting process.  It is obvious that the vacuum formed edge has to go, so I decide to start at the leading edge and take off just enough to remove the lip and give a good finished edge.  This will be the forward reference point.  The next cut is to set the rear most point of the lens in the recess.  Now that both the front and back fit within the recess, the rest of the recess edges can be traced through using a sharpie to mark the lens.  A few more cuts are necessary here because I want to sneak up on the actual dimension carefully rather than risk going too far.

After this it is a matter of carefully sanding down the edges until the fit is good.  The belt sander makes this process a snap, but many trial fittings were required.

When the lens fits snugly with a small, but even gap all the way around it's ready for the edge finishing.  I used #320 and #800 sandpaper on the edges and finished with plastic compound on the buffer.

The next step is to set some nut plates in the wing tip to retain the lens.  With the lens in place I drilled a hole through the lens and wing tip for the screw.  Then with the nutplate located, the ears can be drilled through.

So here is the nutplate ready for rivets.  Because the recess edge was so close to the rivets, I had to use a back-set which is much smaller than the mushroom set I would normally use for a counter sunk rivet. 

And that's about it for one lens.  One more to go.