48 A highly effective VTOLtransition system is key to building a modern multirole UAV. An uncrewed aircraft that doesn’t need launch or recovery infrastructure, and can passively generate lift on fixed wings, is inherently a more flexible solution than one without these capabilities. The demand for such solutions is reflected in our coverage in previous issues of different VTOL-transition configurations, including quadrotorhybrids, tilt-rotors, tail-sitters and the unique transversely folding wing of the Pterodynamics X-P4 (issue 41, December 2021/January 2022). However, tilt-wing aircraft – in which the main wing pitches upwards relative to the fuselage during lift-off to orient its propulsion nacelles vertically – are largely missing from the types that have had commercial success as UAVs. Crewed tilt-wings are of course nothing new. For example, there was the 5 t Canadair CL-84, four of which were built between 1964 and 1972, and the 15 t Ling-Temco-Vought XC142, of which five were built. However, mechanical failures and high pilot workloads resulted in them not being pursued at scale manufacturing. But just as tilt-rotor and tail-sitter configurations were also once shunned for crewed aviation, so Switzerlandbased Dufour Aerospace is attracting attention for its Aero2 tilt-wing UAV. The company has designed its hybridpowered, 208 kg MTOW UAV for a range of applications, particularly for users in cargo and medical logistics. It has a 40 kg payload capability, a 150 kph cruise, a 3 hour endurance and a host of redundant systems. Most important though, the Aero2 incorporates technologies that overcome the issues with previous tilt-wings. Company and design history The Aero2 was conceived by Dufour’s cofounder and CEO Thomas Pfammatter, who was previously a helicopter pilot for emergency medical services. From 2015 to ’16, he had also worked with Dominique Steffen, another Dufour cofounder, to build the Aero1, the world’s first piloted electric aerobatic aircraft. “They became enthusiastic about the power and efficiency capabilities of electric propulsion, and that drove them to start looking into possible eVTOL aircraft concepts,” recounts Jasmine Kent, the third Dufour co-founder and now its CTO. “Around 2017, when they realised they’d need a much more robust control architecture than the manual system on the Aero1, they contacted me and presented their vision for a crewed aircraft that could replace helicopters Rory Jackson explores how this large tilt-wing UAV is positioning itself as a long-range solution for commercial applications Full tilt Although the Aero2 began life as a scaled-down prototype of a large, crewed eVTOL concept, customer demand for a UAV of its size motivated Dufour Aerospace to develop it as a product (Images courtesy of Dufour unless stated otherwise) October/November 2023 | Uncrewed Systems Technology
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