As Adler's video demonstrates, the domed upper surface of the frisbee suppresses roll by moving the center of lift back to the center of gravity. The Aerobie achieves this with a slightly higher angle of attack of the trailing airfoil. --rwg DanA>This isn't quite the same, but in frisbee catch, it's fun to throw it in a tilted plane with some serious CW spin, aimed far to the right of the target person (I'm a righty). It will then curve in a wide arc -- at first it looks as if it will miss by a mile -- back to the target. Just as if it were sliding along a roof. --Dan RWG writes: << . . . I've probably mentioned this before, but flying, spinning disks (smoothly) zigzag. . .