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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
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