Splattered insects may seem like the least of your worries when you're tearing through the air at more than 500 mph (800 km/h), but for those working with Boeing's ecoDemonstrator 757 they present a pretty unique opportunity. NASA has carried out testing of a series of non-stick coatings on the aircraft's wings, finding that one inspired by lotus leaves showed good potential to shrug off blasts of bug guts to lessen drag and, by extension, ease the consumption of fuel.
The latest stage of testing with Boeing's modified 757 airliner began back in March, with the aim of developing new technologies to improve aviation efficiency, cut down on noise and reduce carbon emissions. Part of this is studying how the environment can impact on natural laminar flow. Aircraft with laminar wings can save five to six percent on fuel when flying long distances, but when bugs build up on the leading edge its benefits can be diminished.
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The testing took place in Shreveport, Louisiana, a site chosen partially for its heavy population of bugs. As bugs don't fly as high as typical altitudes of plane flight, the tests were tailored to include extra take-offs and landings across 15 flights over a period of around two weeks. In total, engineers from NASA and Boeing examined five different non-stick coatings on the wings, all designed to minimize residue left behind by squashed bugs.
Part of finding a solution to the problem was studying bug chemistry and what exactly occurs when an insect comes into contact with something at such high speeds. The team found that as the bug's body bursts, its blood actually goes through chemical changes to make it more adhesive. After looking to nature for potential answers to this, the material scientists explored lotus leaves as potential inspiration to prevent the fluid from sticking to the surface.
"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," says Mia Siochi, senior materials scientist at NASA. "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."
Throughout the testing, researchers from NASA's Environmentally Responsible Aviation Project were on hand to monitor the results of the different coatings. They reported that the lotus leaf-inspired coating brought about a roughly 40 percent reduction in bug body count, compared to a control surface placed alongside it.