Issue 45 | Uncrewed Systems Technology Aug/Sept 2022 Tidewie USV Tupan | Performance monitoring | Bayonet 350 | UAVs insight | Xponential 2022 | ULPower UL350i and UL350iHPS | Elroy Air Chaparral | Gimbals | Clogworks Dark Matter

66 Insight | UAVs Wide-area surveillance Thailand is responsible for almost 300,000 sq km of exclusive economic zone and more than 3200 km of coastline, making persistent surveillance as well as search & rescue capabilities critical maritime priorities. Natural disasters such as the 2004 Sumatra- Andaman earthquake and tsunami, as well as more man-made ones such as chemical leaks and oil spills, also demand quick humanitarian responses and disaster relief capabilities. In addition, economic and infrastructure developments require versatile aerial platforms to conduct precise 2D/3D survey and mapping at minimum costs. As a result, UAV development is high up on Thailand’s national agenda. For example, the Swiftlet is a multi- purpose UAV developed by the Royal Thai Air Force and the National Research Council of Thailand. It is categorised as a fixed-wing tactical UAV, and has a 5.5 m wingspan and a 100 kg MTOW. It is based on a modular design, a composite structure and current uncrewed technologies. It has an endurance of up to 10-12 hours compared with the 6-8 hours of previous iterations of its design. Cobra International, a Thailand-based composites manufacturer, has been able to use its knowhow to reduce the Swiftlet’s weight considerably, which has been key to the craft’s endurance, by using a CNC-machined carbon sandwich material for the internal structures, with glass and carbon-fibre reinforced PVC foam sandwich skins. The Swiftlet prototypes were made by using a combination of wet layups and vacuum bagging, with some parts infused and some parts using pre-pregs. As a result, the composite airframe weighs about 32 kg, or one-third of the craft’s MTOW. “The Swiftlet is the fifth UAV we’ve worked on at Cobra,” says Danu Chotikapanich, CEO of Cobra International. “The r&d project has been so successful that it will probably lead to industrial production of Swiftlets. “Plans have been made with the r&d team to introduce a more efficient engine and to improve the consistency, precision, durability and finish of production airframes with our composite facilities and equipment. “And the project we worked on before this was a VTOL-transitioning UAV called the VETAL, for Thailand-based HiveGround.” The VETAL is designed for large-scale surveying and mapping, particularly in crop monitoring missions for the vast plantations of Southeast Asia and elsewhere. It has machine learning (ML) visual data processing to enable analysis of parameters such as canopy area and height calculations, crop yield estimations, weed and disease detection, automatic fertilisation requirement calculations – both type and quantity – and automatic planning of the spraying pattern. HiveGround’s use of ML also extends to offering pre-launch flight planning functions such as automated route mapping, swarm mission control, mission progress comparison and 3D flight area volume calculation. The VETAL is a flying-wing design with a 1.3 m wingspan and measuring 1 m long and 0.7 m tall. Its battery gives it a maximum endurance of 60 minutes and a top speed of 108 kph, with a payload capacity of up to 800 g. In addition to RTK and PPK processing of its GNSS data for precision mapping, it integrates a 2.4 GHz data link for live telemetry, as well as 5G and 4G cellular link options. A GCS 4G tablet is ruggedised to the MIL-DTL-810G standard, and comes with the company’s HGMC GCS software. HiveGrid ‘s embedded fleet management software is also available. Summary With all the solutions investigated here, it might seem peculiar that the singular term ‘UAV’ is used for vehicles that can be fixed- wing or rotary, STOL or VTOL, tail-sitter or tilt-rotor, mechanical or bio-inspired, and weighing from 25 to 2000 kg. We now see different uncrewed terrestrial vehicles being referred to as AUGVs, Q-UGVs, AMRs, self-driving cars and so on, and underwater systems as ROVs, micro-AUVs, LUUVs and XLUUVs. In light of this, it makes sense to develop a new taxonomy to describe the far larger and more diverse UAV ecosystem. Whether that leads to reclassifications such as XLUAVs or uncrewed tilt- rotors styled as UTRs, or more creative approaches, remains to be seen. There is no doubt though that, much like the design and engineering presented here, the best framework taken will be that which the market finds most helpful and appropriate. August/September 2022 | Uncrewed Systems Technology The Swiftlet has a 5.5 m wingspan and was co-developed by the Royal Thai Air Force and the National Research Council of Thailand (Courtesy of Cobra International)