The acceleration of metal foils under irradiation by powerful proton beams with power density 0.05-0.5 TW cm-2 and particle energy 0.5-5 MeV has been studied. The results of the numerical simulation have been compared with the experimental data on back surface velocity registration of the aluminum target (at the KALIF accelerator) and with simple analytical model calculations. The hydrodynamic efficiency of 10 mu m tungsten foil acceleration as a function of proton beam parameters has been investigated.