Inside Unmanned Systems

JUN-JUL 2016

Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.

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38 unmanned systems inside   June/July 2016 AIR NEW TECH cally insulate noisy engines from the outside world. "There's a carbon fiber [material] with a foam core that we use that has pretty good [sound] transmission loss for its weight." Besides military and police operations, there are many good reasons to try to go quieter. In the civilian world, researchers monitoring wildlife by drone may not get access to the ani- mal in its natural state if it reacts to a buzzing quadcopter. A study conducted last year found that black bears, at least, seem to show stress when drones fly overhead. According to an im- planted heart-rate monitor, one bear's heart rate jumped from 41 to 160 beats per minute. The animals appeared on video to be unper- turbed by the f lyovers, which suggests that animals can be stressed without displaying it outwardly. Gaeta is working to start a project studying how drones affect livestock. "Is it going to affect how they behave? Does it affect (the ranchers') livelihood?" He is also working with fellow Oklahoma State University professor Jamey Jacob on a project to detect the acoustic signatures of tornadoes to hopefully provide better warning. [See Inside Unmanned Systems' piece, 'Drones Could Provide Earlier Tornado Warnings.'] But listening for a tornado becomes more dif- ficult if the aircraft doing the listening is mak- ing its own noise. And noise is popping up as a problem even in unexpected places. "Areas I didn't even think [noise] would be an issue turn out to be an issue," Gaeta said. "Even big stretches of pipeline inspection where you would think the populations are small—but even then, the people you f ly over aren't appreciative of having these noisy things f lying relatively low to their homes and farms." Another area that could benefit from quieter UAS is filmmaking. "The noise interferes on set, and results in added time and money to post-process the foot- age. And in the world of live streaming news, sporting events, [and] nature filming—(noise) is a disturbance and restricts use," Mat Rowe, co-founder of New Zealand-based Dotterel Technologies, told Inside Unmanned Systems. Nanofber Shrouds Dotterel believes it has a solution. It's built nanof iber-based noise reduction shrouds that surround a vehicle's rotors, dampening the sound and directing what's left upwards, away from people and away from cameras and microphones. "The shrouds have innovative acoustic ma- terials incorporated that specifically absorb noise within the speech ranges," Rowe said. "Our shroud also protects [the rotor blades] along with the reduced noise and with it, we can also make sure the efficiency goes up enough that it counteracts the weight of the shroud, so you don't lose f light time." For now, the shroud prototype reduces noise such that a typical drone sounds twice as far away as it really is. That earned the Kiwis the Most Innovative Product from industry web- site News Shooter during the National Associ- ation of Broadcasters' annual meeting in April. Dotterel is working on licensing its product to a number of companies and hopes that its noise- reducing shrouds will be shipped with commer- cially available vehicles by this time next year. No vehicle can be completely quiet. Even with a nearly silent propeller and engine, "you would start to hear what we call the airframe noise," Gaeta said. "Just the fact of an aircraft f lying—the landing gear make noise, the slats and f laps make noise." Gaeta firmly believes noise is an issue that will need to be addressed by the UAS commu- nity. "As we open up the airspace and have more and more commercial operations, there's going to be an outcry for noise regulations," he said. "The minute we get these in the air, it's the first thing people will complain about." On the other hand, he said, "if you design a quiet [vehicle], they won't even know it's there." "THE SHROUDS HAVE INNOVATIVE acoustic materials incorporated that specifcally absorb noise within the speech ranges." Mat Rowe, co-founder and managing director Dotterel Technologies Drones Could Provide Earlier Tornado Warnings http:// insideunmannedsystems. com/drones-could-provide- earlier-tornado-warnings/ RELATED STORIES ONLINE Photo of black bear courtesy of Jon Sullivan via Wikimedia Commons

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