Here is a quick impression.
I'm assuming just displaying whether it gets over the net or not will be the desired information.
I'm assuming whether or not it gets over the net will gracefully decrease as the speed decreases.
That makes me think of something like a contour plot with one contour for each speed and the points on the contour be the height,angle.
So can you look at
and find a way to get one contour for each speed?
I suppose you might even think about a 3D plot where the points speed,height,angle where it just barely makes it over the net make up the surface.
Does any of this give you ideas for how to start?