Fully Sheeted Wing
sheeted wings can either have a built-up rib and spar structure or a
hot-wire cut foam core.
Built-up versions have a rib pattern that is
identical to that of a D-Tube wing. The thickness of the sheeting is subtracted
from around airfoil to make the pattern.
Most builders have difficulty with their first built up sheeted wing, but
the experience is valuable and a poor initial result should not dissuade you
from trying it again.
You will not see too many
fully sheeted, built-up wings on sport models for several reasons.
As I mentioned already, many builders are afraid to even attempt it because
significantly more skill is required to build a sheeted wing than other types.
The ribs must be sanded to flow smoothly from one rib to the next in order
for the sheeting to lay smoothly without undulations.
Additionally, it can be difficult to sand the
skin smooth at the seams.
This is mostly a problem with poor technique or using the wrong glue.
The skins should be sanded after joining them but prior to gluing them to
the rest of the structure.
Excessive sanding after the skin is glued to the ribs will cause it to have a "starved
This is because the sheeting sands away at a faster rate
where it is supported by the ribs which results in ripples in the skin.
In the worst case it is possible to sand through the sheeting at the ribs.
Sheeted wings also weigh more than a non-sheeted wing, but only marginally
more than a D-Tube wing.
Most builders do not build fully sheeted wings for the above reasons and the
fact that a fully sheeted wing does not fly significantly better than a
Sport models having fully sheeted wings most commonly have a foam core which
are exponentially easier to build. The main drawback of a foam core
wing is weight. A properly designed and well built balsa wing will always weigh less than an
otherwise identical foam core wing.
Some people will claim that they can build a foam core wing that weighs less
than a balsa wing. Without exception, every person who has made this
claim to me could not produce a wing to back their claim. I'll believe
it when I see it.