"Peter Duniho" wrote in message ...
"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

So, tying this into a couple of recent threads... can a frisbee stall?
What would happen if it had dimples on it?
How about vortex generators? : ' )

Joe Schneider
N8437R



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