Methods for Attenuation of Helicopter

Helicopters can be a source of loud noise. The high production noise of helicopters makes them unsuitable for densely populated areas, especially in low-flying conditions. This study examines methods and offers solutions to reduce or eliminate the noise produced by helicopters. Several methods have been considered to reduce the noise produced. Solutions such as muffler for motors, use of modulated blade spacing, X-force control, reduced tip speed, blade tip modification, airfoil tailoring, Increasing the number of main rotor blades, active blade control and variable diameter rotor in The rotor and the use of the strut in the gearbox were introduced. According to the studies conducted in the present study, combined methods haveas the best noise reduction. although Independent methods reduce noise, depending on the amount of reduction required in the targeting, combining the methods can be achieved the appropriate answer.