Rich:

The 21 X 8 spun on a ZDZ 40 at around 8K on a Dave Plat Extra 300 until the wing broke off. Most violent thing I have eve seen a airframe do, and was not much above stalling. Thing flapped its wings like a bird, for a few moments. The prop still lives, probably go to E-bay soon. DP did not believe what happned, probably why is is gone!!!