How does forward airspeed impact the rate of descent during autorotation?

Forward airspeed has a significant impact on the rate of descent during autorotation. Generally, there is a specific airspeed that produces the minimum rate of descent. At airspeeds below or above this optimum airspeed, the rate of descent will increase. At lower airspeeds (approaching a hover), the induced drag is much higher and the blades produce less lift; therefore the rate of descent increases. At higher airspeeds (above optimum) parasite drag becomes greater and the rate of descent increases. Therefore, pilots use a specific airspeed during autorotation to minimize the rate of descent and maximize glide distance, giving them more time to select a landing site and prepare for the landing. This optimal airspeed is typically found in the helicopter's flight manual.