Evaluation Of Vortex Ring State (Vrs) Onset And Entry Fidelity In Helicopter Flight Simulators

Abstract

Helicopter flight simulators offer the potential to train pilots in recognizing, avoiding, and recovering from hazardous flight conditions such as Vortex Ring State (VRS). However, current FAA and EASA simulator qualification standards lack objective fidelity requirements for VRS onset representation, relying primarily on subjective assessments. Thus, this paper presents an objective evaluation method to assess how accurately different simulation models represent VRS onset. Using flight test data, from dedicated flight tests on a Robinson R66, and flight test results from the literature, fidelity criteria were established for key VRS onset aspects: collective trim position, vertical acceleration fluctuations, and sudden increases in descent rate. These criteria were used to evaluate three models: an H125 VR reduced-motion platform simulator, a FLIGHTLAB model with Peters-He inflow, and a more advanced but non-real-time FLIGHTLAB VVPM model. Results showed that while the VR simulator and VVPM model captured important VRS characteristics, they both had limitations. The Peters-He model failed to represent VRS onset cues. These findings highlight the need for improved simulation models to enhance VRS avoidance training effectiveness.