[icegreentea2]

For ballistic objects (so objects where air just acts as drag), the optimal launch angle is less than 45 degrees due to air resistance.

For aerodynamic objects like a disc, the optimal launch angle will be complicated because a disc's flight path is far more influenced by "secondary" (such as angle of attack and spin) compared to say a baseball, or even golf.

An "optimal" description of disc release angle that a player would likely be interested in (I say this as an ultimate player) would be given in terms of release angle, angle of attack (ie: how nose up), spin, and forward velocity.

And then once converted into human terms for all but the most elite athletes, release angle will probably instead be simplified down to windup position and release position/height.

[amenghra]

Right. Even something that seems simple (such as a golf ball) is not trivial to model: the rough surface and spin end up creating lift -- the ball is essentially flying.