monitor and occasionally control the aircraft BVLOS from Farnborough, even if it’s surveying over a remote disaster site or warzone and beaming live video down to somewhere nearby. “Frequency approvals primarily define what radios and bands we won’t use. The S band is widely used commercially, which means we can easily find we’re coming within range of another vehicle or organisation using it and hence risking link loss or congestion. But as mentioned we have safety back-ups in place for that.” The UHF radios are able to hop between different frequencies within the band, and avoid specific ones depending on the mission profile. Tyler reports that AALTO was asked not to use three UHF frequencies in particular during a flight earlier in 2023. “The overarching goal is to be able to beam high-rate data from anywhere on Earth, and we’re not far off from that, especially if we look into adopting mesh radios in the near future,” he adds. “Meanwhile, the positioning of our S-band dipole on the fuselage tail means it generates no turbulence, and the UHF antenna sticks out of the trailing edge of the wing, also conforming aerodynamically, and with either omnidirectional antenna covering the others’ ‘null’ point for consistent GCS comms.” Future plans AALTO anticipates serving markets across Africa, the Middle East, India and South America, as well as Australia and North America, although it is also in talks with prospective users in Japan and elsewhere. “Those include persistent and ad hoc connectivity for civil work such as disaster response and military applications like ISTAR,” Tyler comments. “When Zephyrs aren’t actively working, they can loiter in the stratosphere for months at a time. They can then take over for others that are reaching their 200-day maintenance intervals or showing signs of faults, to sustain 5G coverage or persistent monitoring.” AALTO also remains aware that it has gathered a large and valuable body of stratospheric data, and is debating internally how best to offer it, and how the Zephyrs can gather more of it, to organisations such as NASA. “We’re also working on the next version of the Zephyr, which will be designed more for manufacture,” Tyler says. “Our development roadmap has us freezing the configuration of the Zephyr next year for the next stage in the Type Certification process. “We’re working closely with the UK CAA for the Type Certification, and as a new Type it’s going to come with a lot of new lessons for us all, particularly given how we just don’t fit into any existing category of uncrewed system. “Thankfully though there’s a growing portion of industry starting to cater to the uncrewed HAPS industry, and that is bringing new kinds of electronics and batteries along together with other novel inventions that are very suitable for our purposes.” 45 Uncrewed Systems Technology | December/January 2024 AALTO Zephyr 8 | Dossier AALTO Zephyr 8 Fixed-wing UAV Solar-electric Wingspan: 25 m Length: 8.5 m MTOW: 75 kg Empty weight: 25-30 kg Payload capacity: 45-50 kg Endurance: 200 days (theoretically unlimited) Cruising speed: 50-60 knots Launch and landing speed: 4-6 knots Maximum barometric flight altitude: 75,000 ft (22,860 m) Some key suppliers Solar cells: Microlink Devices Batteries: Amprius Transponders: uAvionix Carbon fibre: Formtech Composites Electric motors: Newcastle University GNSS-INS: Advanced Navigation Specifications AALTO is now working on a designed-for-manufacture version of the Z8 to go through Type Certification, while keeping an eye out for new technology as it grows
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