Height y in megameters (top panel) and vertical velocity v_y in kilometers per second (bottom panel) of the central arcades’ apexes in function of time t in minutes for σ = 1. Colors ranging from black to orange correspond to lower-lying arcades to higher-lying arcades, respectively. The thick black line corresponds to the evolution of the flux rope center. The vertical red line marks the time at which footpoint driving is disabled (t = t₁).