Full-span flaperons as airbrakes?

I don't know of any sailplane design that uses full span single surface
flaperons.


I know I'm getting in late on this but the original LS-3 had one full-
span control surface per wing panel. It was fairly flexible (said
anyone who ever removed one from the wing for maintenance) and
apparently required a fair amount of lead to mass balance (IIRC, 40
lbs. was mentioned, probably split between left and right). The result
was that the wings were not only quite heavy (175 lbs.each) but the
balance was biased towards the trailing edge, making it more awkward
to handle during rigging. Maximum flap settings were -7 to +10
degrees, probably to prevent the one-piece surface from distorting or
even splitting/buckling at the trailing edge at higher wing
deflections. The wing itself was very stiff (probably another reason
for its weight since this was pre-carbon fibre) so the deflection in
turbulence was low (read: it was a rough ride on the ridge). It sounds
a little odd but the glider was a joy to fly and both climbed and ran
very well when new. Alas, LS-3s experienced shrinkage over the spar
caps over time, which hurt the cruise performance though they still
climbed well. Some owners (including me) sanded and/or added gel coat/
filler to restore the original profile and the glider was transformed,
making it equal to the ASW 20, Ventus, and LS-6 of its day. It's still
a great, wonderfully strong airplane with a lot of performance that
gives its owners a great deal (for one with a good finish).

Not to be confused with the LS-3a or LS-3 17, both of which had more
conventional flap/aileron control surfaces and lighter wing panels.

Chip Bearden
ASW 24 "JB"
USA