Preface- When I say roll, I'm referring to the flight angles of pitch, yaw and roll. Disc golfers also refer to this as hyzer angle.

Suppose an overstable PDGA style disc is thrown with a right hand backhand (RHBH). Looking down on the disc from above, the disc spins clockwise. The roll angle turns left (or hyzer). Compare this to a right hand overhead "thumber" throw. This throw is also spinning clockwise. However, the thumber throw rolls right (or anhyzer). Even more so, the thumber thrown flight often completes an entire 360 degree "barrel roll" before landing. What flight mechanics are in play that cause the thumber to roll the opposite direction from a backhand?


If I understand your question correctly, you're describing what I would call a hammer throw where the disc is near veritcal over the head at release and whether a thumber or backhand delivery is clockwise spin for a right-handed throw. The side of the disc moving forward provides lift and counters the angle of hyzer in a regular frisbee disc, but not so much with golf discs because of the additional weight of the discs, hence overstable discs tend to fall to the angle of hyzer. This particular throw at first appears to defy that logic except that because of the angle of release, the lift generated by the faster forward-moving part of the disc is working -with- gravity instead of against it and therefore turns even harder, in this case turning harder to the left, or as you describe it, rolling to the right. If you release the disc at the same angle, but flipped 180 degrees it will not not drop off to the left much at all, if any, and will tend to hold that angle until it makes contact with the ground and rolls. It all comes down to the flight dynamics of the naturally-designed lift working with gravity instead of against it.

I hope I've explained this clearly - it's not easy to describe.

I personally use this shot as an up-shot if there are obstacles in front of me that I can clear by throwing over, but want the disc to come down flat and -not- roll or skip.

Bill Hileman PDGA #1577


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