Soft Helmet Design for a Launch/Entry Space Suit
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This paper describes the design and development of a soft helmet for an IVA space suit. The suit is designed to be worn during launch, ascent, and entry, to protect crewmembers from a variety of hazards and contingencies, most notably cabin depressurization. The paper focuses on the innovative soft helmet design, which drastically reduces stowage volume and suit mass, while preserving field-of-view, integrated communications, CO2 washout and crew protection. Multiple helmet concepts are discussed and traded, including conformal and non-conformal hard helmets, and various soft helmet architectures. The choice of helmet for a given suit/vehicle is driven by multiple factors, including stowage mass and volume, field of view, suit-seat integration and head/helmet/headrest coupling, head-borne mass, head protection and crew survivability, unpressurized and pressurized comfort, and ease of use, among others. Soft helmet variations that include hard visors, soft visors, full and half disconnect rings, and pressure sealing closures of varying designs are all discussed, leading to the chosen soft helmet design. Data from evaluations of multiple soft helmet designs are presented, demonstrating the advantages of the chosen design. Several design iterations are also presented, which served to increase field-of-view, improve CO2 washout, and drastically improve don/doff times and ease of use. The final design includes a hard visor, but does not incorporate a suit-to-helmet disconnect ring. Head protection and integral bidirectional communications are provided through an internal, head-borne communication and head protection assembly. This soft helmet design works best within a continuous flow ECLSS architecture, the benefits of which are discussed. An integral pressure sealing closure allows crewmembers to open the visor for a majority of nominal suited operations, but easily, quickly and repeatably close and seal the visor when needed. The soft helmet design enables a suit that is extremely lightweight; ~60% lighter than historical pressure suits.