34 points of the UAV aimed at increasing its stealth capability have driven its demand to eclipse that of other successful uncrewed defence aircraft. A major part of this is Primoco’s aforementioned use of fibreglass throughout the hull and structure; most high-end UAVs are made from carbon fibre, which despite its strength-to-weight superiority is grievously easy to detect, causing carbon-built aircraft to “light up on radar like a chunk of metal” as Fojtik puts it. As a result, other such UAVs are easily detected and destroyed in and around disputed airspaces, and so many other UASs being offered to customers involved in active conflicts are no longer being sought by discerning defence procurement officers. By contrast, Primoco continues to operate directly and increasingly above combat zones without losses. Much of that is thanks to the company’s stealth and anti-jamming approaches. A lot of the anti-jamming strategy revolves around the autopilot checking, cross-referencing and fusing data from a pitot tube on the nose, static barometric sensors on both sides of the fuselage (for when the UAV is in a banked turn), an IMU (with magnetometer) and a 72-channel, multi-constellation GNSS receiver with access to GPS, BeiDou, GLONASS and Galileo. “The first consequence of jamming is often that GNSS readings for speed and altitude start changing too much and too quickly, but IMUs, barometers and pitot tubes work just fine amid jamming,” Fojtik adds. “So we’ve programmed alarms alerting operators to potential jamming when GNSS position and speed start conflicting with the inertial and pressure readings. “Also, with many of our components we don’t go dual-redundant. Dual redundancy isn’t actually required in STANAG 4703, but the overall philosophy is the same: if one sensor isn’t enough for safety in flight or landing, another picks up the slack by tracking data in a different way.” Protecting against jamming is often limited to a UAV integrating a GNSS that works across a wide spectrum, so that when one section of the spectrum is being jammed, the receiver switches to another section, which is often sufficient. “The problem is that in some active war zones, there’s jamming across ultra-wide frequency bands, which is why we have so many countermeasures,” Fojtik says. “We have one other navigation system, a proprietary technology that I can’t explain in detail, but even in a completely GNSSdenied or spoofed environment, we can fly and gimbal-track really precisely. That’s vital because if you find, say, a tank or artillery at some other target, and you lack reliable position data, the find is useless. “This system is completely independent of inertial, GNSS and air data – all I can tell you is that it’s radiobased. It’s a big part of what’s allowed us to fly every day in jammed conditions.” Parachute If the landing gear should still fail, or damage makes standard landings impossible, the recovery parachute is deployed to enable a slow emergency landing. When an emergency landing is triggered, a small ballistic rocket housed in a tube and tethered to the top of the parachute is launched upwards from the parachute box, tearing through the upper cover on the front of the fuselage and lifting it away from the rest of the aircraft. The rocket hence pulls the parachute up quickly, allowing it to rapidly unravel and fill with air to begin slowing the UAV’s descent even at low altitudes. As the One 150 falls, the parachute points the nose upwards, preventing payload sensors from being the first point of impact with the ground. The tail and landing gear point downwards, having been validated for load bearing and shock absorption such that the force of impact on touchdown is not transmitted to any of the electronics. August/September 2023 | Uncrewed Systems Technology Dossier | Primoco One 150 The parachute enables a slow, controlled emergency descent if the landing gear should fail or damage makes standard landings impossible
RkJQdWJsaXNoZXIy MjI2Mzk4