Mass Properties Comparison of Dismounted and Ground-Mounted Head-Supported Mass Configurations to Existing Performance and Acute Injury Risk Guidelines

Abstract In order to limit the aviator’s exposure to potentially unsafe helmet configurations, the U.S. Army Aeromedical Research Laboratory (USAARL) developed the USAARL Head-supported mass (HSM) Performance Curve and Acute Injury Risk Curve as guidelines for Army aviation HSM. These Curves remain the only established guidelines for Army HSM, but have limited applicability outside of the aviation environment. Helmet developers and program managers have requested guidelines be developed for the dismounted, ground-mounted, and airborne operating environments that consider currently fielded and proposed HSM configurations. The aim of this project was to measure mass properties (mass and center of mass offset) of currently fielded and proposed HSM configurations and compare them against the existing USAARL HSM Curve guidelines. Mass properties were collected for 71 unique dismounted and ground-mounted HSM configurations. None of the 71 HSM configurations met the Acute Injury Risk Curve recommendations, and only 11 of the 71 configurations met Performance Curve recommendations. While some helmets fell within acceptable limits, the addition of night vision goggles and protective masks pushed all configurations outside of the recommended guidelines. Future guidelines will need to be expanded to consider the operating environment, movement techniques, and primary mechanism of injury.