High-Performance Composites

MAY 2014

High-Performance Composites is read by qualified composites industry professionals in the fields of continuous carbon fiber and other high-performance composites as well as the associated end-markets of aerospace, military, and automotive.

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M A Y 2 0 1 4 | 6 3 FEATURE / PLANT TOUR unique in this size aircraft." As a UAV, its larger internal vol- ume permits more payload and sensors. In the manned light aircraft market, it means more cockpit comfort, and greater cargo and fuel capacity. There are also no wings to break off upon landing, improving aircraft recovery for UAVs, and it of- fers the option to be powered by compressed natural gas (see "A UAV fueled by CNG?" sidebar, bottom of p. 61). With support from North Carolina State University (NCSU, Raleigh, N.C.), computational fuid dynamics (CFD) analysis and wind tunnel testing were completed in October and No- vember 2013, managed by Dr. Richard D. Gould, chair of the Mechanical Engineering and Aerospace Department. Accord- ing to Skillen, results have exceeded expectations. The air- craft generates 20 lb/44 kg of lift at 0° angle of attack (i.e., no tilt relative to the airfow direction), which equates to 100 ft/ sec (31 m/sec) at 68 mph/109 kph. In other words, the aircraft generates lift quickly without requiring a lot of speed to take off. "That's almost twice as aerodynamically effcient as most other light aircraft," says Skillen. It also demonstrates good dynamic stability (ability to recover after disturbance from normal fight), and no further modifcations will be needed prior to fight testing. NCSU will help here as well, says Skil- len, by fying the 1:4 scale aircraft with a telemetry package to map out all of its fight characteristics and, thus, verify the CFD analysis. Prototype to production "We are applying modern CFRP technology to make the tradi- tional performance of blended wing body aircraft even better," says Skillen. The aircraft's structurally effcient shape elimi- nates the need for high-strength spars. Thus, the airframe is essentially hollow. Beyond its top skin, bottom skin and four ribs that make up the body, the only other parts required are vertical fns and fight control surfaces. Skillen asserts that this makes the KittyHawk easy and cost-effective to manufacture. Such a design, however, requires large, unsupported, high stiffness-to-weight structural panels. "This is the sweet spot for CFRP construction," Skillen claims, noting that, here, "C- PLY furthers the weight savings possible, with skins that are signifcantly lighter than if using 3K plain-weave fabric." C-PLY source Chomarat North America's C-PLY production line in Anderson, S.C., will produce any stitched multiaxial configuration, but is optimized for 100-inch/2.5m wide 0° noncrimp fabric, stitched to layers angled from 30° to 90°. Fiber angles less than 30° are no problem, but are produced at a reduced width. Source: Chomarat 0514HPC IM PlantTour-OK.indd 63 4/22/2014 4:01:02 PM

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