To improve helicopter performance, there are four problems to be solved, i.e. engine power-up, drag reduction, retreating blade stall prevention and prevention of compressibility phenomena on advancing blade.
To solve above problems, in this paper, various methods with constant speed rotor are compared by analyses and wind tunnel tests.
As the results, feasibility of 180 knot helicopter, a compound type helicopter withfixed-wing thrustpropeller, will be justified.