NASA Coatings Seek Smoother Splats
Something is really bugging scientists at NASA, driving them to develop coatings to solve their pesty problem.
A group of researchers (dubbed the "bug team") at NASA's Langley Research Center in Hampton, VA, has been flight-testing coatings that could reduce the amount of bug contamination on the wings of commercial aircraft.
Why? Because heaps of high-velocity bug guts can seriously slow down a jet.
Tracking 'Bug Accumulation'
The bug team put the coatings through a series of takeoffs and landings on the HU-25C Falcon aircraft. The work is part of NASA's Environmentally Responsible Aviation (ERA) project.
When insects get in the way of an airplane's wings during takeoff or landing, the bugs disrupt the smooth flow of air over the wings, creating more drag and increasing fuel consumption, which, in turn, leads to increased pollution as that fuel is burned.
"The reason we do these tests at low altitudes or do a lot of takeoffs and landings is because bug accumulation occurs at anywhere from the ground to less than 1,000 feet," said Mia Siochi, a materials researcher at NASA Langley.
Sizing Up the Splat
The researchers attached surfaces with engineered coatings and then an uncoated control surface to each wing of the HU-25C, testing a total of eight coatings.
"We fly [test] controls and assume that if the other surfaces were not coated, they would get the same density of bug strikes," Siochi said.
So, if the engineered coatings come back with fewer bugs than the control surfaces, they are working. The bug team discovered that the coated surfaces had fewer and smaller bug splats.
The size of the splats was also important. And one of the notable differences between the coated and the control surfaces was the smaller area of bug residue, the team said. In some cases, the height of the residue was also reduced.
It could still be some time before these coatings end up on commercial airlines. The coatings also have to be durable enough to withstand a long time in operation and will have to undergo environmental durability testing for conditions like rain, humidity and ultraviolet radiation.
The bug team started by shooting crickets and fruit flies through a desk-sized wind tunnel to learn how insects adhere to different coatings.
Siochi added that the fuel savings would also have to make up for the cost of applying the coatings. "So we have to get through that hurdle of practical application of these materials," Siochi said.
Before it could test the coatings, the team had to learn more about how insects adhere to various coatings. That's where BART comes in: the Basic Aerodynamic Research Tunnel. This desk-sized wind tunnel is equipped with tubing that the team refers to as the "bug gun."
"We're shooting bugs at about 150 mph as we try to mimic takeoff and landing speed, but the bug is moving and the target is stationary. In reality, it should be the other way around," Siochi explained.
At first, the bug team was using crickets because they shot uniformly in the bug gun, but they were too big for the wind tunnel. The team then switched to fruit flies, which they get from the fruit fly shop and propagate for a long-lasting supply.
And just how is NASA acquiring all of these bugs?
"By the thousands. In a tackle shop. With a credit card," Siochi said. "After checking with our procurement officials and the legal office to make sure there were no regulations against using insects like this."