CompositesWorld
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NEWS CompositesWorld.com 59 Next-Generation Launch Vehicle 500 XL Series. e former, for use in a geosynchronous transfer orbit (GTO), features a solid-fueled CASTOR 600 (two-segment) first stage and a CASTOR 300 second stage, with the cryogenic upper portion, and a payload capacity of 5,500-8,500 kg. e 500 XL Series comprises a CASTOR 1200 first stage and a CASTOR 300 second stage, with a payload of 5,250-7,000 kg, designed for geostationary equatorial orbit (GEO). e 500 Series will be equipped with a 5m diameter by 15m long payload fairing, while the 500 XL Series will have an identical fairing or one measuring 5m diameter by 20m long. John Slaughter, the company's VP of commercial programs, says the NGL has completed critical design reviews of the first and second stages, a procedure that finalizes the basis for design of the solid rocket motors. It has also built the first CASTOR 300 CFRP case at its refurbished 6,132m 2 case production facility in Utah. e company uses a proprietary filament winding process it developed in-house to manufacture the case. is fabrication process, Slaughter reports, has become one of the company's core competencies. First, PAN-based HexTow IM7 12K carbon fiber (Hexcel, Stamford, CT, US) is wet-wound employing a proprietary CLRF-100 epoxy resin, also developed by Orbital ATK. e fiber, a high-tensile and high-modulus aerospace-grade qualified to the NMS 818 CF Specification (NCAMP), has a density of 1.78 g/ cm 3 and a filament diameter of 5.2ยต. Notably, when winding is complete, but before final cure, the case is removed from the mandrel and a peroxide-cured EPDM (ethylene propylene diene monomer) insulation layer is wound on the case's inner diameter. Although it's conventional practice to apply the EPDM first down on the mandrel, then overwind it with the carbon fiber, anoma- lies can be introduced into the rubber surface during demolding, Trial wound case undergoing final evaluation Orbital ATK's first 3.66m diameter by 9.5m long Castor 300 carbon fiber case is shown during manufacture via a proprietary filament winding process at its facility in Magna, UT, US. Hexcel's HexTow IM7 12K fiber is wet wound with a proprietary resin, CLRF-100, also developed in house. After winding, the case is removed from the mandrel and EPDM rubber is wound on the case's inner diameter, providing an insula- tive layer of uniform thickness. The CF case and insulation is co-cured in an autoclave; the final thickness of the carbon layer is 25.4 mm in the main cylinder region and 66 mm near the joints, which are used to connect combinations of the segments. The completed case is currently undergoing final testing. The company plans to begin full-scale manufacturing in late 2018 or early 2019. Source | Orbital ATK caused by friction at the rubber/mandrel interface. Orbital ATK's two-step alternative, made feasible by the large diameter of the case, improves consistency in the rubber layer's thickness. e rubber is then cured in the case in an autoclave at an unspecified temperature. Total postcured thickness of the case's carbon fiber wall is about 66 mm near the joints and approximately 25.4 mm in the cylinder region. Orbital ATK has previously used CFRP in the manufacture of components for its space vehicles, most recently in the S.S. John Glenn Cygnus spacecraft, which completed its supply mission to the International Space Station this spring. e spacecraft's circular aft deck structure is designed with a CFRP skin; a CFRP/ aluminum honeycomb core sandwich panel comprises the rigid substrates of the vehicle's solar panels. e company also has used CFRP in the cases built in Utah for the Titan GEM and Orion solid-fuel rocket motors. e carbon fiber cases being built for the NGL, however, are unique in several respects. "is is the largest