When you pull on the VG line the cross bars have to move back
along the keel. There is a Delrin ring connected to the cross bar junction that
slides along the keel when you move the cross bars back. You want that Delrin
piece to slide as smoothly as possible. There are already plenty of forces
pushing against you as you pull back on the VG line, so keeping the slider
action as smooth as possible is important for pilot comfort and reducing pilot
fatigue after many VG pulls.

Silly me, I thought that the keel was just a piece of aluminum tubing. I didn't
think much about what Wills Wing (and I assume other manufacturers) might do to
that tube to make sure that it was smooth and stayed that way. I just fly 'em, I
don't build 'em.

I got interested in the keel tubing, when I looked at the new keel (that is
being tested) that you'll find on some new Wills Wing T2C's (not on mine or Jeff
O'Brien's, but on Jeff Shapiro's and a few others). They are black anodized, I
thought to go along with the optional carbon fiber stinger. Yes, there are a few
carbon fiber stingers out there in the testing phase (for strength and
durability). I'll have some pictures soon.

But when I spoke with Wills Wing designer Steve Pearson, I got a short lesson in
keel surfaces. Wills Wing first polishes the keels-to-be before it sends them
out to be anodized. This is the first part of the smoothing process. There are
three different anodizing processes that Wills Wing has used, one which they
won't be using in the future.

There is Type II (clear), Type III (hard), and Bright dip (and others)
anodizing. Almost all aluminum used in a glider is anodized other than some
interior sleeves. You can read more about it
here.

Anodizing increases corrosion resistance and wear resistance, and
provides better adhesion for paint primers and glues than bare metal.

Wills Wing used to have its keels Bright dipped, but the company
that was nearby them that used to do it is going out of business because it
would be too costly to upgrade their operations to meet new environmental
standards. This does not mean that anodizing can't be done in a way to meet
these standards, rather that it can be too expensive to update existing
facilities.

Wills Wing is having another company do Type II anodizing to its aluminum
pieces, which was standard for most of them anyway. It is experimenting with
Type III anodizing, and on the keel, also baking on a layer of Teflon as part of
the anodizing process. The Type III anodizing makes for a nice slick surface to
begin with (especially when combined with the initial polishing), and adding the
Teflon layer just ups that even more.

But there are problems. Type III anodizing produces a very hard surface. So hard
that it almost immediately destroys regular drill bits. Even very expensive
carbide bits ($100/each) are quickly destroyed. So there are currently
production problems, which need to be worked through to make this work.

Making something simple and easy to use, like a VG, is actually very
complicated. It must be simple because the pilot has a lot of other things to
think about when flying. It's nice to know that Steve Pearson is back there
thinking about just how to make things simple.