Outflow power (top) and mass outflow rates (bottom) along the DR21 Main outflow. The vertical navy blue line shows a typical errorbar for observations assuming 20% calibration error (see Table 6). The light blue lines show a range of outflow power assuming a fraction of cooling, f_x, of 0.21 and 0.37 (top), and a range of mass loss rates assuming various shock velocities, v, of 20 and 60 km s⁻¹ (bottom).