Modern helicopters still suffer from many problems that hinder a further increase in their
efficiency, acceptance and hence their market share. The high level of vibrations and the …

The current technologies for developing quiet rotor noise in urban canyons are reviewed.
Several passive noise control approaches are discussed with their limitations in reducing …

This study employs a 1.6 m diameter rotor to validate the global active noise control method,
developed from our previously work, which is based on near-field acoustic holography and …

With the popularity of multirotor aircraft, the aerodynamic noise it generates has an
increasingly serious impact on the environment. A fast method for globally predicting the …

Boeing and a team from Air Force, NASA, Army, Massachusetts Institute of Technology,
University of California at Los Angeles, and University of Maryland have successfully …

Reducing rotor aerodynamic noise is an important challenge in helicopter design. Active flap
control (AFC) on rotors is an effective noise reduction method. It changes the segment airfoil …

This article offers a new perspective in defining comfortable helicopter flight along with two
solutions based on passive and active main rotor morphing. Constrained optimization …

The low-frequency in-plane thickness noise generating from the displacement of air by
rotating blades has an important influence on helicopter detection. An on-blade control …

An electrically controlled rotor (ECR), also called as swashplateless rotor, replaces a
swashplate with a trailing edge flap system to implement primary rotor control. To investigate …

Active rotor control of helicopters is the future development direction, and active flap control
(AFC) is one of the most promising technologies. However, the numerical simulation of an …