30 Dossier | Primoco One 150 over wide areas, for example by scanning thousands of square kilometres of open sea per hour for enemy ships,” Fojtik adds. “You could use zoom cameras for that, but their narrow FoV makes multispectral imagers the more efficient option. And across all our different sensors, AI object recognition and detection enable us to identify credit card-sized objects from 2 km away.” The UAV has also been able to integrate Lidars, radars (synthetic aperture and Ku band), and some military intelligence sensors including satcom interceptors, IMSI (international mobile subscriber identity) catchers, and VHF/UHF transmission directional finders and analysers. “Sensors like those, combined with AI software and advanced systems like SAR, mean we can find enemies, casualties or missing persons through cloud cover, fog or forest canopies, or hiding in really dense crowds. Using the One 150 for something simple like agricultural survey in clear weather for example would be overkill,” Fojtik says. Primoco has also flown with flight calibration instruments for certifying the navigation systems of a twin-engine Beechcraft to airworthiness standard tolerances. This was done in August 2021 in partnership with Norwegian Special Mission (one of Europe’s leading flight calibration providers) to prove that an uncrewed aircraft could perform such critical services for a crewed aircraft. The size of the One 150 meant the Beechcraft’s antennas, computers and software were integrated without needing to miniaturise them (as is often done for UAVs) so the calibration was performed at a fraction of the usual cost. Primoco therefore anticipates making flight calibration a focus of its future commercial offerings. Structure and hull Stealth is a major reason why the One 150 is fibreglass rather than carbon. Although it has a superb strength-to-weight ratio, carbon is easily detected by radar. Fibreglass is radar-transparent though, and allows Primoco to build its hulls using ‘out of autoclave’ manufacturing and to heat treat them using straightforward processes. The material can also be repaired in the field, which is challenging with carbon layers. If a crack is found in a carbon part, an autoclave is often needed to re-bond the fibres and resins. “We had fuselage damage on one occasion, and we re-baked and repaired it overnight in a military tent – not something you could do with carbon,” Fojtik says. “We could save lots of weight by switching to carbon, but the low radar cross-section and ease of manufacturing and repairs makes fibreglass more than worthwhile.” For geometric strength, the One 150’s wing contains two beams – one main, one ancillary – running the internal length to maintain structural robustness, with about 12 ribs inside each wing along the lengths of the beams. The ribs are concentrated about the mounting points for each tail boom to reinforce them. “It’s a stiff design; the maximum load factor is limited by the autopilot to 2 g, so with our MTOW of 150 kg you can’t technically exceed loads of 300 kg of force during flight; perhaps 600 kg if you account for gusts,” Fojtik explains. “But as per STANAG 4703, we’ve tested it to survive up to 1.5 t. Theoretically, we can adjust the autopilot’s load factor to allow freer flight and manoeuvring under severe conditions like high turbulence.” Vector autopilot A key rule in choosing the autopilot for the One 150 was that it could not be a development product but a mature solution, production-ready and fieldproven. Even so, it had to be tailorable for new capabilities and performance features on an ad hoc basis but remain reliable for controlling flight and subsystems. In addition, it should not be difficult to source. These requirements led Primoco to select UAV Navigation’s Vector-600. Being manufactured and supported from Spain, EU licencing and easy importing were both a given, and Fojtik reports that UAV Navigation routinely provides quick turnarounds on new functions whenever requested. For instance, UAV Navigation instituted audio warnings for issues such as engine problems or data losses, in case GCS operators fall asleep or lose concentration from the inevitable monotony of their shifts and warning lights alone are not enough. Primoco’s in-house GCS hardware can be installed in a mid-sized van as a mobile command centre, reducing set-up overheads for field operations. It features four monitors (touchscreen if requested) and two pairs of keyboard and mouse for two operators in the loop simultaneously. “That creates redundancy in case one computer fails, and the GCSs run UAV Navigation’s Visionair autopilot software, so updates at their end August/September 2023 | Uncrewed Systems Technology The landing gear incorporates telescoping structures to absorb the shocks of hard landings
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