Unmanned Systems Technology 038 l Skyeton Raybird-3 l Data storage l Sea-Kit X-Class USV l USVs insight l Spectronik PEM fuel cells l Blue White Robotics UVIO l Antennas l AUVSI Xponential Virtual 2021 report

29 that are quite small by comparison,” he adds. “We’ve also used a SAR from Radionix, which is really useful for visualising geography and detecting objects below the UAV when cloud cover would block EO sensors.” Knyazhenko notes, “We don’t use Lidar so much, except for power line and road inspections, partly because of the huge density of data that needs to be processed from Lidar sensors but also because cameras achieve essentially the same result and level of accuracy across many applications at a far lower cost – not just financially but in data terms. A 3D map made from camera images consists of maybe one-tenth the gigabytes of a Lidar-constructed map.” Flight systems The airframe has four control surfaces – an aileron on each wing, and two elevators on the tail. These are controlled by an autopilot that is assembled largely in-house. Although Skyeton used Pixhawk in the Raybird-3’s first year of development, it has since found it quicker and safer (in terms of supply chain security) to bulk-buy microprocessors and sensors, and build similar architectures in its own autopilots. “We use a few different GNSS-IMU systems, to right-size the navigation system’s power consumption as well as the accuracy with which images are geo- stamped, according to the end-user’s mission profile,” Stepura adds. For some missions needing higher accuracy, Stepura says VectorNav’s systems have been used for precision geo- tagging while keeping to SWaP targets. “We have experienced perhaps 1-5 º /hour of bias drift during flight with that MEMS system, no more, which is even better than it says on their datasheets,” he adds. For missions that need even more precise geo-referencing and coordination, a fibre optic IMU such as one of KVH’s systems can be installed to enable reductions of flight deviations to less than 0.1 º . That will reduce the maximum payload weight by 1 kg but ensures highly accurate navigation and data geo-tagging. “Granted, some of that is also helped by our own real-time software corrections,” Stepura says. “For example, GNSS-IMU systems don’t account for the drift you get from wind, or have insufficient wind estimation or prediction systems for decent attitude corrections.” As Knyazhenko explains, “Our autopilot software takes constant data inputs from onboard sensors for wind speed and direction, as well as temperature and humidity, so we can correct for wind-induced drift affecting our navigation readings. “That’s really critical for operating in remote areas of Canada or the US for example, where GNSS connectivity is very sparse and you could lose a UAV without accurate, real-time attitude corrections for wind vectors and velocities.” Comms The comms architecture has also been designed largely in-house, again for supply chain security – many suppliers having refused to export their products to Ukraine – and Skyeton’s engineers now feel satisfied that the overall system improves over COTS solutions in Unmanned Systems Technology | June/July 2021 Raybird-3 Fixed-wing UAV MTOW: 23 kg Wingspan: 2.96 m Nominal operating ceiling: 3500 m Nominal endurance: 18-28 hours Cruise: 110 kph Nominal payload capacity: 5 kg Data link range: 120 km Nominal flight range: 2500 km Fuel consumption: 250 ml/hour Some key suppliers Engine: OS Engines Generator: in-house Propeller: Mejzlik Propellers Navigation: VectorNav Technologies Transponder: uAvionix Autopilot: in-house Video datalink: Silvus Technologies EO/IR gimbals: Octopus ISR Systems/UAV Factory Synthetic aperture radar: Radionix Specifications Various antennas and radios can be used on the UAV and GCS to ensure compliance and consistent connectivity across the RF regulations in different countries