Very interesting thread ! Mark, are you working on a
simulation model for the winch launch ? Such a tool
would allow us to optimize this very important flight
phase in various conditions. In real world the air is
different each time you launch, so it is very hard to
know after a good launch if you did better, or if the
wind or a thermal helped you, even with an alti
logger... With a math model you can set the atmosheric
parameters and play with different settings...
About your elevator preset during launch and rotation:
i wonder if additionnal flap deflection would'nt help
in this phase. This moves backward the center of
pressure of the wing which help stabilize the plane,.
No matter the drag, it gives you maximum lift which
is, for sure, necessary in this phase. Then, when
"critical" altitude is reached, less flap may help to
find a better compromise "lift/drag" (I mean here
"still hudge lift/ but not to much drag") so the
glider climb fast... Maybe both elevator and flap
presets are necessary for the transition phase, what
do you think ?
But while saying this i'm going for this question:
what is the optimal setting for the flaps ? For a
given airfoil, between launch at let's say, 10 m/s,
and the end of the climb (before zoom) at 40 m/s 50
m/s, or more, the Reynolds number varies a lot !
Appart from handling qualities, is the optimal flap
setting the same between 10 m/s and 50 m/s ?? Do we
know if we want the higher Cl, no matter the drag ? Or
a compromise ? If we can identify this compromise, is
Xfoil able to predict the airfoil performance
accurately ?
Thanks for your work, wish you many interesting
flights for 2006.
Loïc
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