CompositesWorld

DEC 2018

CompositesWorld

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NEWS CompositesWorld.com 35 Composites space tourism 3 In general terms, composite manufacturers build sandwich structures in one of two ways: One is a multiple stage system where plies of prepreg fabric are laid up for the outside skin in the designated fiber architecture to meet specified loads and conditions — with appropriate sacrificial films and layers. The layup is vacuum bagged, debulked and cured. The film adhesive and core are then arranged over the skin laminate. The inside skin and film adhesive can then be similarly laid up and cured. Other manufacturers use a single-stage system where the entire structure is laid up, vacuum bagged, debulked and cured in a single operation. 4 An SS2 fuselage skin panel is subjected to a thorough debulking process to force out any air trapped between the prepreg plies. Entrapped air can lead to porosity or other flaws in the final cured product. Typical debulking includes pulling a vacuum on the layup before cure. 5 Parts are typically oven-cured at the recommended resin time and temperature for OOA cure. After cure, parts are de-molded and prepared for assembly. Photo shows upper half of SS2-003 cabin ready for assembly, with windows and emergency egress ports cut out. The crew and passenger cabin is 2.3m outside diameter (OD), by 3.7m long. Side windows are 43 cm OD; top windows are 33 cm OD; crew station windows are 53 cm OD. 6 Finished parts are assembled primarily by bonding, with addition of metal fasteners as needed. Photo shows assembly of SS2 fuselage and wing. The leading edges of the wing and the horizontal stabilizer are faced with a thermal protection system derived from NASA's Space Shuttle program's thermal insulation systems. increase drag and reduce speed for re-entry into Earth's atmo- sphere. If the spaceship were re-entering Earth's atmosphere from low-Earth orbit or higher, a dierent technology would be required to withstand greater heat and g-forces associated with re-entry from those altitudes. At SS2's re-entry point from the edge of space, though, the feather is a sucient and inventive way to safely slow the descent. (Following a deadly accident due to premature feather deployment during a test in 2014, TSC redesigned the system to prevent a repeat of this failure.) Similar to the eect of a badminton shuttlecock, the right-angle position of the feather induces high drag forces from oncoming air resistance. Further, it holds the SS at the correct aspect, descending belly down, to safely re-enter Earth's atmosphere. …e ship is not powered during descent, but glides toward its desti- nation. As it approaches the ground, the pilot again extends the feather to its normal wing position for safe landing. …e wing and feather are both carbon ‡ber composite sandwich structures, built from the same materials and process as the WK wing and the fuselage sections. …e feather includes a set of small wings called the feather aps that are attached to the

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