High Fidelity Helicopter Lag Damper Model for Comprehensive Rotor Analysis

Helicopters with articulated rotor blades are subject to the well-known ground resonance where the rotor lag mode interacts, in an unstable fashion, with fuselage roll. To eliminate this ground resonance, both lag dampers and fuselage roll dampers are required. The Sikorsky UH-60 helicopter platform, which comprises the vast majority of utility rotorcraft used by the US Army and the Navy, relies upon a set of four hydraulic dampers for safe operation. The current comprehensive rotorcraft analysis tools however lack accurate modeling capabilities to predict the force, displacement, and dissipative nature of lag dampers. The methodologies used in these current comprehensive tools usually oversimplify the complexity of the dampers and incorporate significant assumptions about the operational environments and system parameters. To address the NAVAIR need for designing fluidic lag dampers, Materials Technologies Corporation (MTC) and its team members, Georgia Tech and Sikorsky Aircraft Corporation, propose creating a robust fully nonlinear modeling approach that inherently employs first principles of mechanics. Once developed, our tool will be coupled with a comprehensive rotorcraft simulation code enabling a quick, versatile and accurate construction of the fluid based (hydraulic and fluid-elastomeric) dampers for rotorcraft analysis.