The K-MAX relies on the two primary advantages of synchropters over conventional helicopters. The first of these is the most efficient of any rotor-lift technology;the other is the synchropter's natural tendency to hover. This increases stability, especially for precision work in placing suspended loads. At the same time, the synchropter is more responsive to pilot control inputs, making it possible to easily swing a load thus to scatter seed, chemicals, or water over a larger area.
So why doesn't everyone do it?