Drones are gaining in popularity as industries from farming to retail to insurance find ways the unmanned flying vehicles can help make businesses more profitable. At Iowa State University, a team of engineers is trying to get ahead of likely complaints about drone noise.
Anupam Sharma, an aerospace engineering professor at Iowa State, takes inspiration from owls to design noise-reduction strategies for airplanes and wind turbines because owls are naturally nearly-silent fliers. Drones challenge Sharma’s team to think on a scale closer to the size of an owl.
“At that small scale, the noise signature is a little bit different, and the source is a little bit different,” Sharma says. “And we believe that at that small scale, the aerodynamic noise is going to be coming from the blades stalling a little bit.”
Sharma says it’s the tiny comb-like structure on the edge of an owl’s leading-edge wing feather that he hopes to imitate to address this particular aspect drone noise.
Drones don’t make as much noise as airplanes or helicopters, Sharma says, but he still thinks reducing the noise they do make will prevent unwanted annoyances as they potentially become ubiquitous. He says drone-delivery of goods purchased online will likely bring many of them right into residential neighborhoods.
“So when they start getting that close to people, that small noise they’re producing is going to be perceptible enough, and annoying enough, that we want to do something about it,” he says.
Sharma points out his work is not focused on the noise the engines make. His work is funded by the National Science Foundation, which recently awarded him a half-million dollar grant, and the Iowa Space Grant Consortium.