The SB-13 swept wing tailless beauty was developed in the early 1990s as a small recreational glider with relatively large upright winglets. The design proved very spin prone.
It occurred to me these vertical "winglets", set upright, would generate a yawing "lift" component in side slip. Since these are set behind the CG, the plane would spin INTO the slip (as the change in relative wind increased their AOA).
This phenomena seems to have similarities to excessive spiral instability in a conventional wing/tail design. Would reducing the size or shape of the winglets help cure this tendency? Or lengthening the nose a bit?