There are many ways to keep a ladder from slipping. The easiest “put on” her old sneakers or shoes with a rubber sole.
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ATLAS PROFILES
PROFILE "NACA-6409". Developed in the early 30-ies in the aerodynamic laboratory of the NAC (USA) for lifting aircraft-biplanes. This profile can be recommended as models of gliders...
AND VANE, AND A SCARECROW
It is known that the established garden weathervane with propeller with its constant sound and vibration that is transmitted through the pole into the ground, drives away from the area...