Hi,

If the wings are level, then, the wind applies an unbalanced force?

If you start from an aircraft at rest or one that enters the crosswind
suddenly from a crosswind-free area (all theoretical of course) it will
be accelerated sideways. You can feel that. F=ma holds true.

Remember, so long as the force remains unbalanced, there will be a
continuous change of speed and/or direction.

The F is only non-zero until the wind has accelerated the aircraft
sideways to it's own speed. After that you move sideways above ground
but the crosswind does no longer excert force on the aircraft and so
the acceleration stops.

If you want to keep a straight track over the ground in the face of
a crosswind you need to accelerate into the wind. To do so you bank,
the horizontal component applies an F to the aircraft, you accelerate.
At this moment the aircraft can "feel" the wind and you get your F_wind
back.

If you bank by just the right amount this F and the F_wind balance each
other at the exact point where you travel above ground in the direction
you want to go.

Does everyone see the problem with this model of crosswinds?

I don't.

Ciao, MM
--
Marian Aldenhövel, Rosenhain 23, 53123 Bonn. +49 228 624013.
http://www.marian-aldenhoevel.de
"Wir brauchen keine Opposition, wir sind bereits Demokraten."