Unmanned Systems Technology 033 l SubSeaSail Gen6 USSV l Servo actuators focus l UAVs insight l Farnborough 2020 update l Transforma XDBOT l Strange Development REVolution l Radio telemetry focus

Government services Periscope Aviation (a subsidiary of law enforcement systems supplier Chartis Federal) is engineering its MK4-R quadrotor UAV to carry mission-critical equipment weighing considerably more than the aircraft itself, for groups in the military, homeland security and the emergency services. The company has recently unveiled a range of precision-engineered tactical UAVs, the newest of which is the MK4-R. As Nick McCarter, president of Periscope and founder and CEO of Chartis, explains, “We wanted to develop the MK4 as a multi-purpose tool for high-risk operations that can behave as a radio tower 51 UAVs | Insight down with the rotation of the rotor discs. This freedom of movement reduces the bending stress on the rotor blades, allowing for a higher rpm and correspondingly higher disc loading than conventional helicopter-based UAVs. It also improves the pitch and roll response as well as top speed, which is currently 60 kph. The E7500 has two vertically oriented dual-bladed main rotors (each measuring 2.3 m in diameter), driven by two 15 kW BLDC motors, as well as a masthead above the lift rotors that mounts four horizontally disposed electric motors for both horizontal propulsion and pitch and roll control. As FulcrumAir’s vice-president of engineering Daniel Clarke explains, “Because of the four small e-motors generating lateral thrust, the ’copter doesn’t really have to tilt nose-down as much for forward motion, which saves power owing to increased translational lift. That means, when you calculate power consumption in this versus a conventional helicopter, we are basically carrying those additional electric motors for free. “This control architecture also keeps the E7500 really stable. It can be hit by gusts of up to 5 m/s and the payload tethered underneath will still be hanging dead still in the air.” While its empty weight is rated at 40 kg, the system can lift up to 60 kg. Running on battery power, it can carry its payload for up to 18 minutes, and has a maximum endurance of 32 minutes when flying without a payload. In its most recent missions, the UAV has been tasked with installing ‘bird diverters’ onto powerlines, hanging the reflective markers to prevent birds from colliding with the electrical cables. The diverters themselves are installed using a heavy and bulky robotic device called the Line Fly (also manufactured by FulcrumAir). “This separate robot, suspended beneath the E7500, has its own flight control computer, batteries, GPS, powered wheels, video system and yaw control thrusters,” Clarke adds. “It is controlled independently from the ground using a Herelink ground station and air unit, and has several operational modes. “In Manual mode, the operator drives it back and forth, triggering the installs. In Auto mode, the Line Fly automatically ‘drives’ along the wire, mechanically installing diverters at preset intervals, based on distance data from its own BLDC wheel motors’ sensors. “Lastly there is Follow mode, which is the same as Auto except we also send GPS data a few times per second from the Line Fly to the E7500 to use as waypoints, so the UAV follows the robot automatically. This autonomy greatly reduces operator workload, but we’re still beta-testing it.” Unmanned Systems Technology | August/September 2020 Animal Dynamics’ Stork UAV uses a parasail designed to maximise the craft’s wing-to-body ratio (Courtesy of Animal Dynamics) The E7500 UAV uses a coaxial rotor configuration, with flapping hinges and additional electric lateral-thrust motors for stable flight and carrying underslung payloads (Courtesy of FulcrumAir)