A Vertical Ejection Simulation Tower (VEST) to elicit the biomechanical responses of the head-neck complex in pilot ejection

Abstract

The modern day fighter pilot, equipped with an array of headgear and helmet-mounted devices, is susceptible to +Gz-induced injuries to the cervical spine. In order to pre-empt such injuries, a comprehensive understanding of the biomechanical response is imperative. A Vertical Ejection Simulation Tower (VEST) was designed to emulate the impact force, velocity and acceleration histories at C7 of a pilot's head-neck complex in a cockpit ejection scenario. The working concept of the VEST is based on a mass-pulley mechanical system that can be operated in a controlled laboratory environment. A free-falling 127 kg guided drop mass provides a force capable of generating an upward accelerative response on a Hybrid III head-neck dummy model via a two-pulley configuration. High speed camera is used to capture the motion of the specimen at 500 fps. The VEST can achieve accelerations of up to 12 G on the model in approximately 100ms through the variation of drop height and pulley configurations. Data obtained from mounted accelerometer and load cell exhibited comparable trend to an ejection situation. Further modifications are undertaken to improve signal trends for experimentation on cadaveric specimens.