The man flying the didn’t know he was violating a temporary restriction on flights around New York City (the president was in town for the 2017 United Nations General Assembly). He didn’t know he had just two minutes to land before he violated the prohibition on nighttime flights. And he didn’t know his DJI Phantom 4—300 feet up, 2.5 miles away from him, and well beyond his line of sight—was flying dangerously close to an Army Black Hawk . At least, not before the aircraft collided. The drone smashed to pieces.
The helicopter, luckily, only suffered a dented rotor and a few scratches, according to the National Transportation Safety Board report. It landed safely, having survived exactly the sort of collision that makes aviation types nervous about the rapid proliferation of drones in American airspace. The sort of collision Kevin Poormon had in mind when he loaded a DJI drone into his 40-foot air cannon.
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Poormon is the group leader for impact physics at the University of Dayton Research Institute, meaning he studies what happens when things hit other things, typically at high speeds. He tests how well armored vehicles really are armored, investigates what debris traveling 4 miles a second can do to spaceships, helps aircraft manufacturers protect their planes against bird strikes, and more.
Late this summer, concerned about the effects of a flood of drones into airspace that already handles more than 40,000 manned flights a day, he decided to produce a visceral image of what a hobbyist UAV could do to an airplane. “We have the in-house capabilities to actually launch a variety of different things, so why not be able to launch a drone, to show what can happen?” he says. He worked with the Sinclair College National UAS Training and Certification Center, which gave him a couple of DJI Phantom 2 quadcopters and loaned him the right wing of a Mooney M20, a small general aviation plane.
For this test, Poormon used his lab’s largest air cannon, a 2,800-pound steel tube with a 12-inch bore. He loaded the Phantom onto the sabot, a slide-like mechanism that carries it through the 40-foot tube, and fired. Compressed air propelled the drone to 238 mph, the approximate combined speed of a drone and a plane coming in for landing. About three hundredths of a second later, the drone smashed into the wing.
University of Dayton Research Institute
The results, captured by a 10,000-frame-per-second camera, just might justify a fear of flying. The quadcopter hits the front of the wing head on, ripping it open and diving inside, like a spoon through chocolate mousse.
“It punctures a hole right through the leading edge,” Poormon says. The drone went deep into the wing, hitting and denting a spar, a vital structural element. “All the weight of the aircraft is suspended on the spars,” Poormon says. “If you damage the spar enough on that side, you would not, um, survive. The aircraft would crash.”
For comparison, Poormon’s team also shot a “simulated bird” at the wing. The pink blob of gelatin crushed a larger chunk of plane than the drone did, but didn’t go nearly as deep or do any internal damage. (They used the faux fowl instead of an IRL bird out of sympathy for the Sinclair students who’d be repairing the wing as part of their coursework. “It’s very difficult to clean up, and would make a mean stink,” Poormon says.)
The Mooney M20 isn’t built to meet the same safety requirements as a commercial passenger jet, but Poormon says the structure and thickness of its wings resemble those of what you’d find on a bigger passenger plane. And while Poorman ran just a single test, it’s an indication that as drones spread, danger could too: Between April and June of this year, pilots reported nearly 800 drone sightings, according to the FAA. Not all those UAVs were breaking the rules, but their number makes clear that these encounters will only become more common.
“Drones are going to be in our future, and they’ll have a positive impact,” Poormon says. “We just have to be careful, and mindful of what can happen if they’re used carelessly.”
And as the crew in that Black Hawk found out, it’s now a lot easier for careless people to join them in the sky—and possibly take them out of it.
