Reconsider the helicopter in Prob. 13??38, except that it is hovering on top of a 2800-m-high mountain where the air density is 0.928 kg/m³. Noting that the unloaded helicopter blades must rotate at 550 rpm to hover at sea level, determine the blade rotational velocity to hover at the higher altitude. Also determine the percent increase in the required power input to hover at 3000-m altitude relative to that at sea level.

18 m Load 14,000 kg