Uncrewed Systems Technology 047 l Aergility ATLIS l AI focus l Clevon 1 UGV l Geospatial insight l Intergeo 2022 report l AUSA 2022 report I Infinity fuel cell l BeeX A.IKANBILIS l Propellers focus I Phoenix Wings Orca

112 in the vicinity of landing pads, and also serves as an alternative to the cellular and satcom systems. Iordache describes PW Link as a robust multi-point, synchronised system with frequency-hopping and spread- spectrum capabilities that enables multiple aircraft and ground systems to talk to each other within 7 to 10 km. Those ranges are achieved with a 100 mW output through omnidirectional antennas, with greater range possible with an output of 1 W through directional antennas, although using the higher power transmissions often requires special permission from regulators. PW Link is encrypted to the Transport Layer Security 1.2 standard. In addition, ‘bridges’ enable Phoenix Wings to open multiple ground-based comms bubbles that provide connections between PW Link and the internet. “This allows us to build a comms network and, if needed, to cover an entire operational area,” Iordache says. “It also allows us to provide coverage in areas not reached by cellular or satcom signals, such as valleys.” The system also lets air traffic control systems know where the Orca is through an ADS-B Out system, which at the moment can only be used in the UK. The navigation system uses GPS and Galileo signals simultaneously, with extra redundancy provided by inertial dead-reckoning available for a few seconds after losing GNSS. Attitude, height above ground level and barometric pressure sensors can be used to control a hover descent, with a manual override available. Proprietary flight control Phoenix Wings developed the flight control system around an STM32 microcontroller from STMicroelectronics. “Developing our own FCS allows us to have full control over the software stack,” Iordache explains. “It makes integration with customer systems easier and more customisable. Also, certification was an important consideration.” In addition to following pre- programmed routes, the FCS can work with integrated transceiver-based in-flight collision avoidance systems such as FLARM, and with sensors to detect non- collaborative air traffic. “At the moment, the flight control computer is the only component without redundancy, and a failure will result in an FTS activation,” Iordache explains. “The upcoming release of our ground control application [GCA] will also plot a ground risk area, which will illustrate the areas that are at risk in the case of an FTS activation,” he explains. “Different regulatory bodies will ask for different mitigations, according to the situation, and a redundant FCS is planned for the future.” Structure and materials The Orca’s monocoque fuselage is made from a composite sandwich skin that takes most of the loads, supplemented by bulkheads for localised loads and to provide extra resistance to buckling. The pallet rail system also plays a structural role, serving as a set of stringers to resist bending loads and providing reinforcement around the opening for the cargo doors in the belly. In the prototype, the fuselage material is mostly fibreglass for its resistance to corrosion and transparency to radio signals, Iordache notes. It is in the lifting surfaces where higher strength- and stiffness-to-weight ratios are essential, so these take the form of carbon fibre sandwich shells that take the torsional loads, bonded to carbon fibre composite spars that resist the bending loads. The fibre is HT carbon, and parts are hand-laminated with an epoxy resin serving as the matrix for the composite, which is tempered at 50 º C after its initial ambient temperature cure. Aluminium alloy to 6061 grade or higher is used for powerplant interface December/January 2023 | Uncrewed Systems Technology The smaller PW One uses the same software and a lot of common hardware with the Orca, enabling it to be used as a proof-of-concept vehicle for route trials Offshore scenarios are interesting, as they have quite high cargo volume demands and most routes can be over water, so safety approval is easier