Evaluation of integrated night vision goggle (NVG) helmets under sustained +Gz.

Three integrated night vision goggle (NVG) helmets from different manufacturers were evaluated under high-G conditions. Structural and operational integrity, as well as neck forces in pounds, were determined via instrumented manikin testing before human exposure with the helmets during sustained +Gz. Results of the manikin testing showed that the helmets could withstand the rigors of high-G, and that predicted forces (using helmet weights and centers-of-gravity) matched those obtained experimentally from load cells in the x-axis of the manikin's neck. After manikin testing, 10 subjects were randomly exposed to four different high-G profiles on the Dynamic Environmental Simulator (DES) man-rated centrifuge located at Wright-Patterson AFB, OH: gradual onset to +8 Gz, a simulated aerial combat maneuver (SACM) profile, and two +4 Gz profiles, one with the mask dangling from the helmet and the other with the mask removed. Fit assessments were conducted before high-G exposure, and one helmet was affected significantly by failure of fit. The degree of migration of the NVG intensified image away from the eyes was affected most by the following helmet characteristics: design of the nape strap, size of the NVG image provided by each helmet system, goodness of helmet fit, and the use of the mask as a stabilizer. Although neck strength of each subject was measured and compared to the degree of head stability while wearing each helmet, no effects were found. However, subjects were not allowed to perform fast, high-amplitude head movements in the centrifuge for safety reasons.(ABSTRACT TRUNCATED AT 250 WORDS)