"cjcampbell" wrote in message
oups.com...
That, and a positive angle of attack. The spin keeps it gyroscopically
stable. As the forward motion decreases the Frisbee begins to settle,
increasing the angle of attack until becomes a kind of parachute.

True, but the increase in angle of attack is strictly a result of the change
in relative wind. The frisbee remains in basically the same attitude
throughout. It has no means of trimming for constant lift or anything like
that.

But
not always. Throwing the Frisbee up will give it a positive angle of
attack as it climbs.

The vertical path is primarily a result of one throwing the frisbee in that
direction. The path would curve down ballistically except for the basic 1G
of lift that the relatively modest angle of attack, basically identical to
the AOA in straight and level flight, provides.

Once the forward motion stops the angle of attack
can become negative,

Negative. As in, not true. The frisbee still has positive angle of attack,
and descends back along roughly the same path it took upward. It's a bit
lazy-eight-ish and, as you know, you don't need negative lift to do those.

generating downward lift and causing the Frisbee
to accelerate downward and back toward you like a boomerang. It comes
down faster than it would simply fall and it accelerates the whole way.

No, it doesn't come down faster that it would simply fall. It does
accelerate, just as any falling body accelerates, and just as the rising
body of the frisbee decelerated on its way up.

If the frisbee had positive lift going up and negative lift coming down, it
would never return to the person who threw it, or even come close. It would
have the same horizontal speed in each direction (reversed when plotted
against time), but significantly different vertical speeds (ie, not simply
reversed), resulting in significantly different flight paths.

Pete