Inside Unmanned Systems

FEB-MAR 2018

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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AIR POWER SYSTEMS 62 February/March 2018 unmanned systems inside It's important to keep in mind, however, that the fuel cell itself and the fuel tank have an ener- gy density of zero, so the fuel tank must be able to hold enough hydrogen so the average energy density of the 2,000 Wh/kg hydrogen and the 0 Wh/kg equipment is beneficial, Robinson said. Most of the platforms f lying today are about 1,000 Wh/kg. Fuel cells systems can only scale down so much, and work best when integrated into fixed-wing platforms, Robinson said. They also can be used in the more robust quadcopter platforms, which are the systems that weigh between 20 and 55 pounds and that have six or 1200 FUEL CELL SYSTEM Protonex uses proton exchange membrane (PEM) fuel cells, which operate at low temperatures, off er quick start-up times, and require only hydrogen and oxygen to operate. The company's fuel cell stacks use a mould-in-place seating approach that provides repeatability and enhanced performance. 600 FUEL CELL SYSTEM Protonex fuel cell systems can increase reliability and decrease operating costs in UAS platforms that traditionally use small internal combustion engines. Benefi ts include low heat and noise signatures, enabling lower altitudes and less expensive payloads. February/March 2018 February/March 2018 FUEL CELL SYSTEM Protonex uses proton exchange membrane (PEM) fuel cells, which operate at low temperatures, off er quick start-up times, and require only hydrogen and oxygen to operate. The company's fuel cell stacks use a mould-in-place seating approach that provides repeatability and 600 FUEL CELL SYSTEM Protonex fuel cell systems can increase reliability eight rotors. The fuel cell systems are typically too big for smaller drones. Flight time and payload capacity are among the biggest challenges Intelligent Energy Senior Vice President Julian Hughes and his team hear about when they travel to conferences—and are two issues hydrogen systems address. "If you can extend the f light time you can actually increase the payload as well," Hughes said. "You have more technology on the drone to do the mission with the same f light time." So while f light time will come down when you add more payload, the drone will still have more endurance than if it was powered by a battery, Hughes said. Adding more payload to these UAS often cuts the f light time to single digits. The heavier the drone, the more energy it uses. While it can be difficult to retrofit a hydro- gen system to a battery-operated drone, it can be done with the Intelligent Energy solu- tion. The company offers that option as well as a system that combines both batteries and hydrogen. Hydrogen systems are also replacing the in- ternal combustion engines that power larger systems, mainly because they're more reliable and less noisy, Robinson said. "Small engines tend to be very noisy, and they tend to have a very short maintenance interval," Robinson said. "Fuel cells are very Photos courtesy of Protonex, a subsidiary of Ballard Power Systems after Protonex. "FUEL CELLS ARE VERY QUIET, AND THEY LAST ABOUT FIVE TIMES AS LONG AS MOST SMALL INTERNAL COMBUSTION ENGINES BETWEEN OVERHAULS." Phil Robinson, vice president, Unmanned Systems, Protonex Technology Corp. HYDROGEN POWERED Fuel Cell propulsion systems for drones

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