This SBIR project proposes to develop a computational tool for helicopter rotor noise prediction based on hybrid Cartesian grid/gridless approach. The uniqueness of this approach is to achieve fully automated grid generation without grid overlapping. As a result, the resulting software will enjoy great ease of use with minimum human interference. There is no grid distortion in the majority of the computational domain. One can apply the best available flow solver which may not be possible to use in the unstructured grid approach. All are important for achieving accurate prediction of helicopter rotor aerodynamics and near-field acoustics. In Phase I, the high-speed impulsive noise will be first investigated and in Phase II, the blade-vortex interaction noise will be further explored.