The simulation of certain time-dependent flow phenomena can pose a grand challenge to Computational Fluid Dynamics. In this paper, a multitime multigrid convergence acceleration algorithm is introduced which significantly reduces the turnaround time to reach time-periodic solutions. The application of this convergence acceleration algorithm will lead to time-efficient simulations of helicopter rotors in forward flight. A comparison between multitime multigrid acceleration and the classical serial time multigrid acceleration shows that an order of magnitude reduction in turnaround time can be achieved at the expenses of an order of magnitude increase in memory use.