bearfoil, it appears it was specifically designed to withstand a force of 36 times the weight of the rudder parallel to the rudder's hinge line. That sounds like tail strike to me. What else would put that specific load on the widget?
That came from just a
few messages earlier by mm43.
And something to consider in your tests - the rudder probably flops around pretty easily. That will upset any airfoil situation, won't it?