NASA says it has completed testing of a non-stick coating for airplane wings that could make aircraft fly more efficiently by "unsticking" pesky bug guts — or if you prefer, insect residue.
Bug guts result in drag, and any increase in an aircraft's drag translates directly into increased fuel consumption, reason enough to consider the benefits of a "slicked-up" wing surface.
To that end, NASA and engineers from Boeing spent weeks in Louisiana testing a number of potential non-stick coatings on the aircraft manufacturer's ecoDemonstrator 757 aircraft.
Because many insects fly fairly low to the ground, the test aircraft made a series of short flights from Shreveport Regional Airport that involved a lot of takeoffs and landings.
It didn't hurt that Shreveport is home to a significant populations of bugs, the researchers pointed out.
Working as part of the Environmentally Responsible Aviation (ERA) Project, the researchers tested five potential coatings — and found one that reduced bug residue by 40 percent.
"One of the five coating/surface combinations showed especially promising results," says Fay Collier, project manage for ERA.
Bug residue on aircraft wings has raised a long-vexing issue in aviation, particularly so on modern aircraft designed to move efficiently through the air.
"Laminar aircraft wings are designed to be aerodynamically efficient," explains Mia Siochi, senior materials scientist at NASA's Langley Research Center in Hampton, Virginia. "If you have bugs accumulating, it causes the airflow to trip from smooth or laminar to turbulent, causing additional drag."
Laminar wings can save five to six percent in an aircraft's fuel usage over long flights, a saving that can quickly be lost to bug splat, she says.
The researchers were nothing if not thorough, even going so far as to study insect chemistry to get a better handle on the "sticky" problem.
"We learned when a bug hits and its body ruptures the blood starts undergoing some chemical changes to make it stickier," says Siochi. "That's basically the survival mechanism for the bug."
As part of the solution, the researchers turned to the natural world — not bugs, this time, but plants. Specifically, lotus leaves.
The reason water doesn't stick to a lotus leaf is revealed under the microscope: A rough surface made up of millions of tiny pointed features.
"When liquid sits on the microscopically-rough leaf surface, the surface tension keeps it from spreading out, so it rolls off," Siochi explains. "We're trying to use that principle in combination with chemistry to prevent bugs from sticking."
