Defence systems | Insight it up to the new Army requirements. Disclosing full specifications of the Mk 4.8 is difficult right now because of the competition, but we can exceed 14 hours of endurance with 13.6 kg of payload.” The Aerosondes are designed and built around a system of common flight and ground controllers, with each aircraft sized differently, running from 36 to 93 kg to cater for varying mission profiles. They include versions of the Mk 4.7 and 4.8 designed for catapult launching and recovery using a net, if preferable. “The Mk 4.7 is powered by the EL005 engine from Lycoming, our sister company, which has supplied the Aerosonde powertrain for many years,” Ryan adds. “It’s a 75 cc, 4.0 bhp engine running on JP8 or Jet A fuel, which we’ve been using since 2012, and the engine has now racked up 600,000 hours of operation and the data associated with it.” To meet the higher power needs of the larger Mk 4.8, Textron has integrated Lycoming’s EL-010, a derivative of the EL-005. Whereas the 005 is a singlecylinder, two-stroke, spark-ignited engine with air cooling, the 010 is effectively a dual-cylinder version. This achieves higher horsepower as well as electrical power for payloads, along with improved balance owing to the two cylinders cancelling out much of each other’s first-order vibrations. “An important feature of the EL-005 engine is its 1000 hour TBO,” Ryan notes. “We work for much of the time as a feefor-service UAS operator as well as our core business of designing and building the UAVs. Powertrain TBO is a major cost-driver for UAS operations, which has really helped drive down our operating costs over the years.” Cross-domain r&d has also played a major role. “Our UAV engineers aren’t pigeonholed into working only on aircraft,” he says. “For instance, they can work on our CUSV [Common USV] for minesweeping or ocean ISR, or our Ripsaw UGVs that we’ve submitted for the US Army’s RCV programme, and vice versa, each team learning from the others. “And we’ve done exercises in which those uncrewed vehicles and their teams talked to each other and collaborated. That included extending the effective range of the CUSV by combining and launching an Aerosonde with it, and we’re looking to carry out more exercises where our different uncrewed systems work together.” Airborne loitering missions When designing UAVs as multi-role tools for military users, manufacturers must occasionally bear in mind that as well as serving as scouts and wingmen to crewed vehicles and human operators, they will sometimes need to function as a sacrificial member, as gathering crucial data on high-risk areas poses the possibility that a UAV will be destroyed while trying to find an enemy’s location. A growing number of UAV manufacturers are taking this one step further by designing their aircraft as loitering munitions or precision strike UAVs. These first perform ISR and monitoring to look for an enemy asset, including UGVs and remote weapons stations, before approaching and using an ordnance payload to neutralise it. Although some loitering munition ‘UAVs’ are little more than glorified cruise missiles, Overwatch Group’s multi-role Pholos UAV has been engineered to provide a static 69 Uncrewed Systems Technology | December/January 2024 The Aerosonde Mk 4.7 HQ is a VTOL-transitioning UAV powered by a Lycoming EL-005, which produces 4 bhp when running on heavy fuel (Courtesy of Textron) Our UAV engineers aren’t pigeonholed into working only on aircraft. For instance, they can work on our USVs and UGVs, and learn from each other
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