https://www.willswing.com/t3/

Carbon Fiber Over-molded Battens

Our carbon fiber over-molded battens are produced in-house and are available for
the longest 4 battens which are most subject to destabilizing and
performance-robbing deformation in high-speed glides. The unidirectional carbon
fiber adds only 20 grams of weight per batten but increases the strength and
stiffness by a factor of 3. Carbon reinforced battens are standard on the Team
Edition and optional on lower trim levels.

The DIY variety:
https://ozreport.com/23.117#2

The discussion about doing this:
https://ozreport.com/forum/viewtopic.php?t=60002

Steve Pearson answers:

1) The battens are a non-critical component without any
consequence to the airworthiest and structural integrity of the glider, and they
are easy to inspect

2) Aeros, Moyes and Icaro have been using spliced carbon/aluminum shafts for
years without any issue, and that construction is very subject to corrosion from
moisture entering the joint without anodizing on the aluminum ID

3) Our battens are epoxy prepreg cured at 150 psi over an anodized aluminum tube

4) I sent a variety of carbon/aluminum samples for accelerated salt spray
testing 2 years ago to access my concerns with other carbon aluminum interfaces
on the glider. The samples fared much better than I expected

5) All of our bonded joints have spacers to ensure a uniform and thick bond line
isolation

6) Some of our parts like the carbon spar also have a layer of glass between the
carbon and aluminum

7) Danny Howells isn’t the only engineer in the world, not that it even takes an
engineer to figure this out. Only a little research, a lot of testing, some
basic engineering awareness and more-than-anything, real-world experience.

8) 7075-T6 is very subject to corrosion, and there was an almost manic reaction
to us introducing 7075 air frames in 1984. Moyes and other competitors fueled
the FUD speculation and predicted all sorts of catastrophic failure. History has
shown that reaction to be unwarranted although it’s still true that 7075 is much
more subject to deterioration in corrosive environments as 6061. None of this
happens overnight and we have ample opportunity to inspect our gliders. I’m more
worried about pilots not pre-flighting their gliders and lack of routine
maintenance like replacing damaged side wires.