Unmanned Systems Technology 024 | Wingcopter 178 l 5G focus l UUVs insight l CES report l Stromkind KAT l Intelligent Energy fuel cell l Earthsense TerraSentia l Connectors focus l Advanced Engineering report

24 Dossier | Wingcopter 178 UAV flight in a very stable manner. Wingcopters are quad tiltrotors with four motors and propellers in tilting modules at the ends of arms that project ahead of and behind the wings on a line that passes fore and aft through the cranked portion of each wing – in other words, through the peaks of the wing as seen from above. The forward pair of arms extend below the leading edge, and the rear pair above the trailing edge, to ensure that little or no downwash from the prop-rotors impinges on the wings to create parasite drag. As the arms position the forward prop- rotors ahead of the wing’s leading edge, induced drag in forward flight is reduced and performance thus improved. Further, the propulsion modules are positioned as close to the fuselage as prop-rotor clearance will allow, minimising bending moments and vibratory response in the wings and their supporting spars, and making the structure stiffer overall. To keep the control scheme as simple as possible, the motor/prop-rotor pods are mechanically coupled through a self-invented mechanism, Kadura says, although he declines to share the exact details of the design. On early Wingcopter prototypes, the pivot point was on the wing at the base of each arm, but the design was changed to move the pivot point to the outer end of each arm so that only the pod containing the motor and the prop-rotor moves. That reduced the loads on the pivot, Kadura explains, allowing a lighter structure to be used. Each motor/prop-rotor pod moves through 90° between VTOL/hover and wing-borne flight modes. “The continuous transition takes about 5 s, has no critical conditions and the Wingcopter stays constantly at the same altitude,” says Kadura. Aerodynamics Wingcopter’s other co-founder, inventor, principal designer and chief technology officer Jonathan Hesselbarth, emphasises that the aircraft is designed to be stable in all flight modes and challenging conditions, and have benign handling characteristics even at the corners of its flight envelope. For example, the swept wings with their distinctive bird-like cranked M-wing planform are designed to ensure that the aircraft quickly and automatically returns to controlled flight after a stall while providing all the lift required within the set size limits. Despite the unusual configuration, standard profiles are used both for the wing and the inverted V-tail. “My main target was to develop a compact VTOL UAV with as much payload capacity as possible in a small form factor,” Hesselbarth says. Applied to the 178’s design, this philosophy was taken further in the heavy-lift version without needing any fundamental changes. Fuselage and structure The Wingcopter has an all-composite stressed skin monocoque, with the wings built as sandwich structures. The motor/ prop-rotor support arms are made from carbon fibre, while the motor cowlings are 3D-printed from a heat-resistant polymer. No metal is used anywhere in the structure. “For the 178 HL we maxed out the payload capacity within the existing February/March 2019 | Unmanned Systems Technology One of the front pair of tilting pods housing a propeller and motor, in fixed-wing mode (Courtesy of Wingcopter) The rear payload bay, carrying a camera linked to a geo-referencing system with the antenna mounted on the payload bay cover (Courtesy of Wingcopter)