Metal additive manufacturing for unmanned aerial vehicle propulsion: a narrative review of recent advances in gas turbine systems

Metal additive manufacturing (MAM) is revolutionizing the design and production of high-performance components across the aerospace sector. This narrative review examines recent research on gas turbine propulsion systems for unmanned aerial vehicles (UAVs), with a particular focus on the transformative role of metal additive manufacturing (MAM) in enabling lighter, more efficient, and more complex engine architectures. The study analyzes the operating principles, performance characteristics, and applications of turbojet, turbofan, and turboprop engines while highlighting key technological advances in hybridization, cycle optimization, and advanced manufacturing. Particular attention is given to MAM of high-temperature alloys (e.g., Inconel, titanium aluminides) and the integration of topology-optimized lattice structures, internal cooling channels, and monolithic rotors. Recent studies on additive manufacturing (AM) for drone components—including metal-doped plastics, composite filaments, and high-performance polymers—provide complementary insights into material selection, structural integrity, and functional integration that are directly relevant to gas turbine development. The study also incorporates the emerging roles of Life Cycle Assessment (LCA) in evaluating environmental sustainability and the use of machine learning for advanced fault diagnostics. Drawing on thermodynamic analyses, experimental studies, and modelling efforts, this review identifies current challenges and future directions in MAM for UAV propulsion, and briefly discusses potential cross-fertilization with biomedical AM, where similar challenges in process control, microstructure optimization, and post-processing are being addressed.