UAVs | Insight aircraft to fly in three flight modes: VTOL, forward flight and “windmill mode.” “In VTOL, it functions like a traditional, multi-rotor aircraft with the propellers pointing upwards to lift the Trio into the air. Once airborne, the aircraft ultimately transitions to a windmill mode, where the three wings spin around the hub, their rotors tilting sideways. The Trio takes the shape of a large propeller, with the rotors providing the necessary torque to spin it around its yaw axis,” says Dennis Krause, co-founder at Angel Aerial Systems. “In forward flight mode, the Trio pitches sideways from vertical take-off until it is flying horizontally. We’ve not finished optimising it for that flight mode, but when activated it uses two of its three aerofoils to generate lift, which gets it where it needs to be quickly and efficiently. “Once spinning in windmill mode, all three aerofoils are generating lift, so the UAV’s rotor speed can drop significantly from the full thrust needed for VTOL, which, in turn, drops the power consumption by 80% compared with normal hovering.” Through its energy-efficient windmill mode, the Trio achieves up to two hours of hover time, compared with 20-35 minutes of hover in a traditional multirotor of equivalent size. While this mode is active, a slip ring, along with a counterrotating motor inside the hub, enables a bottom turret with a camera payload attached to remain static and stable amid the spinning wings above. This allows for the same quality of stabilised video output as a conventional multi-rotor, but over a longer period. Defence & security US-based EchoMAV’s MK-1 has been designed as a durable, long-range, VTOL fixed-wing aircraft that meets today’s requirements of Group 2, 55 lb (25 kg) UAS. It is engineered for simplified deployment using a hybrid power plant with on-board charging, quick refuelling, cost-effective maintenance and diverse payload integration, with a maximum operating altitude of 15,000 ft (4500 m). The MK-1 is constructed modularly, using aluminium and carbon-fibre, grey matte finish components throughout. “Its design centres around being able to take off and land with very little space and no ground equipment, being able to disassemble into a single box, and being able to assemble and launch in under 10 minutes with no support equipment,” says Chip Coffin, aviation specialist at EchoMav. “The wingspan is roughly 9 ft [2.7 m] wide, the fuselage is about 48 in [122 cm] long, and we have separate fins at the tailplane rather than a single, joined, inverted vee because this approach helps with disassembly and the ability to keep all parts compacted together in a case. “We get about six to eight flight hours from the system’s 5.6 L fuel tank at cruise, and maybe 20 minutes after take-off the battery is refilled to 100% state-of-charge.” Power comes from a rear-mounted, gasoline-electric power plant, combining a two-stroke engine running on 40:1 gas and pre-mix. The engine’s motor-generator (which mounts on the output shaft between the engine block and propeller) recharges a 9000 mAh, 12S battery pack, which gives a stable voltage bus for the four lift motors in take-off, with the UAV transitioning into horizontal flight at roughly 200 ft altitude, at which point the engine drives its pusher propeller for cruise. The autopilot governing flight and VTOL-transitioning is EchoMav’s own EchoPilot AI. This consists of an 89 x 53 mm board, its design based on Pixhawk open-hardware standards, and integrating an nVidia Jetson compute module (either the Nano, TX2 NX, Xavier NX, Xavier 83 Uncrewed Systems Technology | August/September 2024 The Trio UAV from Angel Aerial Systems can propel its three blade-like wings around its hub to hover for up to two hours on a single battery charge (Image courtesy of Angel Aerial Systems) The VTOL-transitioning EchoMav Mk1 UAS flies using EchoMav’s EchoPilot AI autopilot, which integrates an nVidia Jetson computer to power AI requirements (Image courtesy of EchoMav)
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