Lightweight Integrally Stiffened Composite Structure Navy SBIR FY2008.1 Sol No.: Navy SBIR FY2008.1 Topic No.: N08-016 Topic Title: Lightweight Integrally Stiffened Composite Structure Proposal No.: N081-016-0686 Firm: Aurora Flight Sciences Corporation 9950 Wakeman Drive Manassas, Virginia 20110 Contact: Wonsub Kim Phone: (703) 530-1904 Web Site: www.aurora.aero Abstract: Aurora's Integrally Stiffened SBCF Panel (ISSP) design and manufacturing approach is a replacement for honeycomb panels. It relies upon the unique forming capability provided by Stretch Broken Carbon Fiber (SBCF), which is unidirectional, collimated short carbon fiber filaments in a prepreg tape format. Uncured SBCF is formed through "stretching" similar to plastic forming of metal, allowing complex shapes to be easily produced at significant layup savings. However, after forming and cure, the discontinuous SBCF filaments provide almost the same strength and stiffness as conventional continuous fiber composites. SBCF forming to date is for single surface skins such as shear webs with formed stiffening beads. While significant labor savings result, these configurations are not suitable for external panels, where many honeycomb parts are used. ISSP features a double skin panel -a smooth outer, air passage skin and a beaded inner skin - to provide structural efficiency and light weight of a sandwich panel, but without a core. The ISSP manufacturing process, successfully demonstrated, produces panels in a single cure cycle. A detailed Trade Study to validate weight and cost vs. a honeycomb baseline design will be conducted in collaboration with Sikorsky and Bell to establish weight, quality and manufacturing costs trade. Benefits: The ISSP manufacturing and design approach can replace honeycomb structure with a weight and cost competitive substitution that is much more durable in the field. This provides substantial direct maintenance cost (DMC) and maintenance MMH/FH reductions on Navy rotary and fixed wing airframes, where corrosion alone currently costs the Navy current $1 BB annually in O&M cost. ISSP promises to be very low cost to manufacture for three reasons - prepreg layups are performed in the flat (vs. on a contoured tool), these flat pattern layups can easily be automated using Automated Tape Layup (ATL), and the complex beaded inner skin geometry is formed in a simple and quick (<10 minute) forming cycle. Current transports entering the market such as the Boeing 787 and Airbus A380 are made from as much as 50% composites as a portion their structural weight. Approximately 25% of the exterior surfaces of modern commercial transport aircraft is comprised of honeycomb sandwich panels, which is widely used for control surfaces such as ailerons, spoilers, rudders and elevators as well as engine nacelles, wing-to-body fairings and wingtip fairings. There is great commercialization potential in the commercial Aerostructures market. Airline operators have similar "readiness" and supportability concerns - aircraft downtime due to avoidable maintenance costs money. Therefore, we anticipate that both the airlines and Boeing/Airbus will have a strong interest in ISSP if it can be developed to meet objectives. Return