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A percussive penetrator is essential for the lunar heat flow probe being developed at the Utah State University. The heat probe is intended to penetrate two to four meters below the moon's surface by percussive motion. To understand the drag as a function of velocity under steady state conditions for the design of the percussive instrument, this study investigate the frictional and dynamic drag effects of a cylindrical rod with a conical tip being pulled through different granular media. The experiment employs a linear actuator to pull the rod through a medium of varying grain size at several constant velocity increments at a constant pressure. Three conical tips of varying lateral surface curvature are used, and the drag force is measured using force sensors. Through the output data, the friction and dynamic drag effects are distinguished and correlated according to the cone type, the medium type, the pull velocity, and the penetration distance. The information and the basic understanding obtained from this research will directly be used in the design of the percussive penetrator for the lunar heat flow probe.
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