Unmanned Systems Technology 027 l Hummingbird XRP l Gimbals l UAVs insight l AUVSI report part 2 l O’Neill Power Systems NorEaster l Kratos Defense ATMA l Performance Monitoring l Kongsberg Maritime Sounder

47 day and 3 hours during the night. “Realistically, we would only fly the older model for up to 3.5-4 hours in daylight and 2.5 hours at night,” says John Brown, chairman and CEO of Silent Falcon UAS Technologies. “The system upgrades included increasing the rated power of the solar panels on the wings from 80 to 210 W without increasing the solar panel area, which really extended our capabilities in daytime flight. We also changed the battery chemistry from lithium-polymer to lithium-ion, and in doing so increased the onboard energy storage from 732 Wh to 1.11 kWh.” The power converter responsible for making the solar power useable for charging the battery or powering onboard systems – the Multi Power Point Tracking device – has also been changed from a COTS system to one designed and built in-house to provide more energy efficiency and the ability to handle higher power loads. Brown says, “Selecting new solar panels was key because we needed something with higher power density, improved power-to-weight ratio, and cost-effectiveness. It also needed a physical robustness that would enable it to withstand the parachute landings the Silent Falcon EE undergoes after flights, and to be worked into the structure of the wings during our carbon fibre lay-up processes.” The Silent Falcon EE uses a ‘flexible silicon’ material on its wings, which provides a 25.5% solar conversion efficiency. After testing a pair of flexible silicon test panels from the (undisclosed) manufacturer, the material was found to meet all the engineering team’s desired parameters, albeit with a slight increase in weight and some minor manufacturing challenges that had to be overcome. The new battery was designed and assembled by Justin Carr, the company’s director of flight operations, who has gained experience in custom-building batteries for FPV racer drones that he operates in his spare time. After obtaining sufficient 21700-type cylindrical cells, he built the new battery according to a theoretical design he had been working on, and ended up with a system that increased the energy storage by 378 Wh while adding only 1 lb of weight. On top of the power system upgrades, the Silent Falcon EE’s GCS uses a new comms system called the SF TriAntenna configuration. This combines two directional antennas with one omnidirectional antenna (compared with the single-antenna system used previously), and test flights so far indicate large increases in bandwidth and far fewer drop-outs when the UAV nears the data link’s maximum range. “The system doesn’t increase the comms range but it makes the data link much more reliable, which is critical for operator confidence when you’re working at the long distances the Silent Falcon EE is to be used at, and in need of high bandwidths and throughput for transmitting data in real time,” Brown says. Also aiming for longer endurance times is Leonardo, which has unveiled the Falco Xplorer, its newest and largest long-endurance tactical UAV. It joins the rest of the Falco unmanned aircraft series, which includes the Falco UAV (featured in UST 5, December 2015/ January 2016). It has a 1.3 tonne MTOW with a payload capacity of 350 kg, a flight time of at least 24 hours and a BVLOS satellite comms capability. The Xplorer is currently undergoing certification for flight in non-segregated airspace (with more flight trials scheduled throughout 2019), to enable it to be flown in civil operations such as emergency responses or coast guard patrols and interdictions, in addition to being designed for defence operators. UAVs | Insight System upgrades included raising the power of the solar panels on the wings to 120 kW without increasing the solar panel area Unmanned Systems Technology | August/September 2019