  In order to elucidate the process underpinning the apparently
counterintuitive phenomena observed in the freefall experiments conducted by E.
Hamm and J. G\'eminard [Amer. J. Phys. 78, 828 (2010)], we construct a simple
dynamical model of a vertically falling train of one-dimensional rigid segments
impinging onto an inelastic horizontal plate in three-dimensional space.
Numerically integrating the nonlinear governing equations, we obtain a robust
result that the train of rigid segments falls virtually faster than freefall
under gravity. The presented model reproduces the coiling spontaneously formed
in the pile, which is considered to be a key mechanism of the phenomenon and is
shown to be a consequence of the three-dimensional spiral structure that arises
due to dissipative locking in mid-air. As one of mechanical keys underpinning
the apparently counterintuitive phenomena, we will here focus the downward
tensile force exerted by the pile.
