  Active filament-like systems propelling along their backbone exist across the
scales ranging from motor-driven bio-filaments to worms and robotic chains. In
macroscopic active filaments such as chain of robots, in contrast to their
microscopic counterparts, inertial effects on their motion cannot be ignored.
Nonetheless, consequences of interplay between inertia and flexibility on shape
and dynamics of active filaments remain unexplored. Here, we examine inertial
effects on flexible tangentially-driven active polymer model pertinent to above
examples and we determine the conditions under which inertia becomes important.
Performing Langevin dynamics simulations of active polymers with underdamped
and overdamped dynamics for a wide range of contour lengths and activities, we
uncover striking inertial effects on conformation and dynamics at high
activities. Inertial collisions increase the persistence length of active
polymers and remarkably alter their scaling behavior. In stark contrast to
passive polymers, inertia leaves its fingerprint at long times by an enhanced
diffusion of the center of mass. We rationalize inertia-induced enhanced
dynamics by analytical calculations of center of mass velocity correlations,
applicable to any active polymer model, which reveal significant contributions
from active force fluctuations convoluted by inertial relaxation.
