Page 17 - Aerotech News and Review 5-20-16

GLOBAL HAWK, from 16 with a medium load and then two more flights plenty of teamwork. Other agencies involved in- to Kim, the process uses a bed of powder, and
with heavy fuel loads. cluded the Global Hawk System Program Office, a laser solidifies the powder to create shapes.
Cory Naddy, director of the Global Vigilance Northrop Grumman Corp., Air Force Test Center Sintering can be done with several materials,
CTF. He said the combination of the testing tech- “We started at lower altitudes and worked our Safety, and many technical experts. “This project including glass, metal and nylon. “SLS al-
niques and the fact that this is an autonomous way up.” Maj. Finlayson. brought the best out of everyone I worked with,” lows for complex geometries without support
unmanned air vehicle made the testing high risk Kim said. “It was very demanding, but I enjoy structures and produces parts that are air and
by wing standards, and required significant effort The pilot said these tests may not lift any fast-paced high pressure work.” water-tight, heat resistant, and strong. This
behind the scenes in the CTF. flight restrictions on the Global Hawk, but they production process effectively saves time and
do open the door. “We’ve shown that the aircraft The simulated ice was made using a process money,” Kim said.
“We actually had the aircraft take off with the is flyable if it picks up a bit of ice,” he said. called selective laser sintering (SLS). According
equivalent of light time icing on the wings and
tail — something that no other aircraft would Kim said making this project happen required
normally do,” Naddy said. “From the moment
we lifted off, we were operating in an envelope Air Force photograph by Chris Higgins
that was unproven and many risk factors were
at play.” A Global Hawk remotely piloted vehicle taxis on the Edwards Air Force Base, Calif., flightline during an icing test mission. The aircraft was fitted with
a 3-D printed nylon structure to duplicate the weight and drag of ice forming on wings and tail.
The director explained they had models for
predictions, but that was it. “Due to thorough
preparation by the team, those models were done
conservatively and the aircraft performed better
than initially expected,” he said.

As project engineer, Kim is new to the flight
testing world. “This is my first real job,” he said.
“I just graduated from Cal Poly Pomona and was
brought on to tackle this project.” Being fairly
inexperienced, he had to learn about what ic-
ing on aircraft entailed by researching previous
studies. “Reports and analyses by NASA and
Northrop were great resources and a tremen-
dous help.”

These forms were then attached to the leading
edges of the wings and ruddervators (the tailfins)
of a Global Hawk.

Before the aircraft was ever flown, the team
modeled the shapes and performed wind-tunnel
testing. Since the Global Hawk is an unmanned
aircraft, accuracy of the flight tests were even
more important. “We had to get it right the first
time,” Finlayson said. “The (Global Hawk) pilot
controls a lot, but not the flight controls.”

Once ground tests were completed, the CTF
prepare the aircraft for actual flight testing. The
aircraft was flown with different fuel loads, first

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May 20, 2016 Aerotech News and Review 17

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