Before they could develop and test non-stick coatings,
the researchers had to study bug chemistry and what
happens when an insect hits a surface at a high
velocity. "We learned when a bug hits and its body
ruptures the blood starts undergoing some chemical
changes to make it stickier," said Siochi. "That's
basically the survival mechanism for the bug."
Then the materials scientists turned to nature for
inspiration -- lotus leaves, to be precise -- to create
the right combination of chemicals and surface roughness
in the test coatings.
"When you look at a
lotus leaf under the microscope the reason water doesn't
stick to it is because it has these rough features that
are pointy," added Siochi. "When liquid sits on the
microscopically-rough leaf surface, the surface tension
keeps it from spreading out, so it rolls off. We're
trying to use that principle in combination with
chemistry to prevent bugs from sticking."
developed and tested more than 200 coating formulations
in a small wind tunnel, then took a number of those to
flight on the wing of a NASA jet. They selected the best
candidate non-stick coatings to fly on the
ecoDemonstrator, while a team comprised of experts from
NASA, Boeing, the U.S. Department of Transportation, and
University of California-Davis identified the best
location for testing.
The Shreveport flights followed another set of NASA tests
conducted with Boeing in
in April using the ecoDemonstrator 757. The Active Flow
Control Enhanced Vertical Tail Flight Experiment
evaluated the effect that 31 devices, called sweeping
jet actuators, have on the aerodynamics of an aircraft’s
tail and rudder surfaces. An aircraft’s vertical tail is
sized large in order to add stability and directional
control during takeoff and landing, especially in the
event of an engine failure. But when the aircraft is
cruising at altitude a huge, heavy tail is not as
Initial results confirmed earlier wind tunnel tests that
suggested designers could reduce the size of the
vertical tail by about 17 percent, decreasing airplane
fuel consumption by as much as one-half percent.
active flow control and wing coating experiments on
board the ecoDemonstrator 757 are part of several ERA
technology demonstrations designed to help reduce
aircraft fuel consumption, noise and emissions.
the exception of Boeing proprietary technology, NASA
knowledge gained through the ecoDemonstrator research
will be made available to the public to benefit