Interesting analysis, but ice anchors depend far more on the quality of the ice and the conditions than the actual strength of the screw. One reason I've heard

Interesting analysis, but ice anchors depend far more on the quality of the ice and the conditions than the actual strength of the screw. One reason I've heard for downward positioning is that the screw can channel heat into the ice and melt faster around it, so a downward positioning acts as a lever to keep the screw engaged.