Dale, I didn't hear back from the guy in Florida who did the pull test.
That said, I was able to screw them all the way into the clay (concrete) that is our taxi and runway right now and if they are screwed all the way in, they will work fine. Probably not keep a tornado from ripping your plane out of the ground, but then, nothing will stop a direct hit.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC