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

30 terms of the antenna parts, radios, filters, coax cables and other components. “We originally conceived it with a single data link for both telemetry and video, but divided them to reduce noise and improve the quality and stability of each link,” Toptun explains. “These days the telemetry link uses a duplex channel system, with a separate uplink and downlink that use spread- spectrum-type noise-like amplitudes to make it very hard for anyone to intercept or interfere with the mission comms. That ensures safe transmissions of 100 or so operating parameters at all times.” Telemetry is typically delivered over one omnidirectional sector antenna or two – one in each wingtip – depending on whether weight minimisation or persistent telemetry is a priority in a given mission, with six sectors around the axis for transmitting performance and navigational data over whichever has the strongest signal. A directional antenna at the control station uses the navigation data to track the Raybird-3’s position and continuously turn to face it. Stepura adds that, depending on the customer and region, Skyeton can adapt its data links to transmit over different frequencies. For example, while many customers want to use the 5.7-5.9 GHz band, different regulations across Asia, Europe and Africa require the use of a wide variety of frequency bands, and the company also often uses 2.1 GHz and 2.4 GHz as standard. Silvus Technologies’ StreamCaster radios are used for the video portion of transmissions, enabling 256-bit AES encryption and up to 100 Mbit/s of live video data. Stepura adds though that since these products are MIMO systems, and since all data links are subject to disruption, the Raybird-3’s StreamCaster also has a back-up telemetry and control link. “We also have one more channel for emergency signals, which goes to a device we’ve designed with just a few simple command buttons,” Stepura says. “These are typically programmed to return to base, open the parachute or shut off the engine, although we can reprogram it depending on a customer’s safety requirements.” This suite and knowledge of comms systems is also critical for the company’s future plans for swarming operations. While there are theoretically many types of swarms – from centralised ones that process commands and data through a GCS, to decentralised ad hoc networks in which UAVs communicate and make decisions among themselves to achieve mission goals – Skyeton has yet to settle on one model. It is continuing its research into optimising data links to see if the latter, more advanced form is achievable before choosing which to develop. Launch and recovery systems The standard pneumatic catapult typically releases the Raybird-3 at a speed of 55 kph, and with force of around 10 g as mentioned, while the parachute is stored in a pointed cap at the rear of the fuselage. When nearing the ground, a single servo opens the cap and releases the parachute. For added protection of the gimbal during landing (given that this is typically the most expensive onboard component) the parachute deploys in such a way that the Raybird-3 pans downward, with its nose facing the ground as it approaches it. “We do this by having the parachute’s lines connected to the undercarriage of the Raybird, running the length under the compartments for the payload, fuel tank and avionics, to pull the tail upright during landing,” Knyazhenko explains. “We attach the lines as part of our pre- flight task list, and it’s an arrangement that makes it physically impossible for the aircraft to tip over onto its payload side when it contacts the ground.” That keeps the payload compartment aperture shielded from the ground, and where necessary a dorsally mounted June/July 2021 | Unmanned Systems Technology Dossier | Skyeton Raybird-3 During recovery, the parachute is released from the rear to land the Raybird-3 on its back, to shield the payload from impacts, while a dorsal airbag is deployed for added protection The telemetry link uses a duplex channel system to make it very hard for anyone to intercept or interfere with the mission comms