Flight characteristics

Curious what exactly makes a disc overstable or understable. Is it shape, weight, combination of the two, or something else?

Without knowing the disc name (Boss, Surge, etc) and it's flight "rating" (-1.5, -2.0, etc) is there some way to distinguish between an overstable disc and an understable disc simply by visual examination.

Occasionally, I get a chance to shift through bins of old discs for sale and the name has faded away or  it's an X-out, or it's a name I've never heard of. I'd like to learn more about how to predict the flight chararteristics without the advantage of being able to throw it to determine.

 

 

 

[Ron Suir]

I, too, would love this info

[Mark Cuban]

I believe a good way to tell is by the parting line height. So the thicker the outside edge of the disc the more stable it will be.

[david swamp thing black]

How domey it is, is a good way to tell. And the angle and sharpness of the edge. 

[Ben Calhoun]

If the rim is concave it tends to make it overstable (think Discraft Xtreme) and if it's convex it should be more understable (think Innova Roadrunner).

Most of the time- if the disc is domey it is likely leaning towards understable- this is no longer always the case- it seems most of the time with wide-rimmed overstable drivers if they're domey in the center but still flatter near the edge, they are more overstable.