Inside Unmanned Systems

JUN-JUL 2019

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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65 June/July 2019  unmanned systems inside expensive payloads, said Gene Engelgau, chief executive officer of Fruity Chutes, in Los Gatos, California. A drone parachute system may also lower insurance premiums, or prove a requirement to get insurance, he noted. The drone parachute industry started to emerge about six years ago to serve as fail-safes for UAS, Engelgau said. "Until drones are as reliable as manned aircraft, I think all drones should have parachutes when f lying over and near people for [their] safety," said Glen Rineer, CEO of Mars Parachutes, in Anaheim, California, who was part of the group that wrote the new standard. "Even the lat- est M200 system and the Inspire 2 systems [both from DJI] just recently had power failures." For example, in September, a drone failed while in- specting a cracked window on the 36th f loor of San Francisco's Millennium Tower, crashing within 10 feet of a little boy. "If a drone fails, the parachute can be a Plan B," Lozowick said. ParaZero's founders were drone operators, and one day "they were operating at a construction site, and they had a drone fall out of the sky, and they realized there was some real risk involved," Lozowick said. Last September, the first FAA waiver to f ly drones over people with a parachute was granted to a UAS operator, North Dakota's Botlink, using the ParaZero SafeAir parachute system on a DJI Phantom 4. The first "waiver f lights" were conducted during a tailgating event, with the drone performing multiple f lights over the crowds gathered in the FargoDome stadium's parking lots, providing real-time footage for local law enforcement and media companies. CHALLENGES FOR DRONE PARACHUTES One key concern drone parachutes face is they are sup- posed to activate not only when drones are falling out of the sky, but also likely spinning and f lipping out of control. As such, when drone parachutes deploy, they risk their canopies and lines wrapping around their drones or getting caught in the rotors of their drones. "It's really bad practice to connect the parachute directly to a UAV," Engelgau said. To overcome this challenge, drone parachutes general- ly include an ejection mechanism that ensures they only open a safe distance away from their drones. "You gen- erally want a distance of about one to two times the di- ameter of the chute separating the drone and the chute," Engelgau said. Several techniques exist for ejecting the parachute. "For smaller systems, there are spring-based systems, which are simple, lightweight and relatively low cost," Engelgau said. "For larger systems, you have ones ejected by gas—that can be compressed carbon dioxide, or some kind of pyrotechnic charge that generates a large volume of gas quickly. Carbon dioxide works well; pyros provide more energy for their weight, but regulatory agencies want to be sure you know what you are doing when you put charges on a drone." Two different techniques can eject parachutes using compressed gas or pyrotechnic charges, Erickson said. Rapid canopy fill ejection uses weights that are attached to the outside and sometimes the center of the parachute to aid in the expansion of the canopy immediately after deployment. "Although this method allows the canopy to extend faster than a traditional deployment, it does not let the canopy travel away from the aircraft with enough speed to reliably escape the roll radius, and has the great- est chance of entanglement," he said. In contrast, ballistic parachute ejection launches the parachute canopy and lines at extremely high speeds, thereby avoiding entan- glement with a spinning drone and overcoming the force from any wind, he added. Drone parachutes generally rely on an automatic trigger system that can deploy the chutes without hu- man intervention. These devices carry sensors such as inertial measurement units, gyroscopes and acceler- ometers, which can detect signs of critical drone fail- ure, "such as it entering freefall, or it f lipping or rotat- ing in a way that would not be part of normal f light," Engelgau said. Fruity Chutes uses the Mayday automatic trigger sys- tem from Mars Parachutes. "It can act in about 0.75 sec- onds," Engelgau said. Mars Parachutes and many other drone parachute companies also offer a secondary, man- ual, way to set off the automatic trigger system. A key challenge for drone parachute systems is reliably avoiding false positives that lead to chute deployment "Airplanes … can glide to some extent, and even helicopters can carry out something similar called autorotation. But with multi-rotor drones, if they experience any issue, they basically drop like a stone." Avi Lozowick, director of policy and strategy at ParaZero Flying Over People DRONE PARACHUTES Standards and Satety DEFENSE COMMERCIAL NEXUS

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