Materials and Energy-Centric Life Cycle Assessment for Drones: A Review

Abstract

The rapid expansion of drone applications across industries such as defense, healthcare, construction, agriculture, and surveillance has intensified the need for advanced materials that enhance performance while minimizing environmental impact. This review provides a comprehensive analysis of materials used in drone construction, categorizing them based on their application in key components such as frames, propellers, wings, and structural supports. An energy-centric life cycle assessment (LCA) examines the environmental footprint of drone materials, emphasizing energy use, emissions, and recyclability. The review highlights the trade-offs between mechanical performance and environmental impact, identifying materials that optimize structural efficiency while reducing environmental impact. Additionally, emerging sustainable alternatives such as bio-based composites and recycled carbon fibers are explored as potential solutions for next-generation UAV design. By addressing existing research gaps, this study aims to guide the development of environmentally responsible drone manufacturing technologies. The findings offer valuable insights into optimizing drone materials for enhanced environmental efficiency, supporting the transition toward more energy-efficient and eco-friendly UAVs.

1. Introduction

Unmanned aerial vehicles (UAVs), commonly referred to as drones, have evolved from military origins into a crucial technology across various industries, including logistics, agriculture, surveillance, construction, and environmental monitoring [1]. The earliest military drones appeared in the mid-1850s [2]. However, in recent years, their popularity and usage have surged significantly due to their ability to perform hazardous and repetitive tasks with high efficiency and at a lower operational cost. In the civilian sector, UAV are employed for applications such as goods delivery, remote sensing, disaster surveillance, traffic monitoring, law enforcement, agriculture, and power line maintenance [3]. The integration of UAVs with green computing and generative artificial intelligence across sectors like agriculture, surveillance, and disaster management showcases significant progress in navigation, object tracking, and UAV communication [4]. In military operations, they are widely used for surveillance, intelligence gathering, reconnaissance, target acquisition, and aerial attacks [5,6]. The selection of materials for drones is primarily determined by their design and intended application. Depending on their configuration, UAVs can be categorized as fixed-wing, rotary-wing, or hybrid UAVs, each optimized for specific applications. Fixed-wing UAVs, known for their endurance and high-speed capabilities, are widely used in defense and long-range surveillance, whereas rotary-wing UAVs offer superior maneuverability, making them ideal for confined spaces and hovering operations. Hybrid UAVs combine the advantages of both but introduce added mechanical complexity. The designs of extensively investigated fixed-wing UAVs vary significantly, ranging from the RQ-4 Global Hawk UAV with a wingspan of 39.8 m to the compact AeroVironment Wasp UAV with a wingspan of just 72 cm. However, fixed-wing UAVs have limitations, including the need for a runway or additional launching and recovery equipment for takeoff and landing [1,5]. Rotary-wing UAVs, also known as multirotor drones, can hover and maintain static positions due to their built-in gyroscopes. They offer excellent stability, flexibility, and maneuverability, allowing them to operate effectively in confined spaces. Unlike fixed-wing UAVs, they do not require dedicated takeoff and landing infrastructure or forward airspeed for flight and navigation. The size and weight of rotary-wing UAVs vary significantly, ranging from the Boeing A160 Hummingbird, with a flight weight of 2948 kg, to the ultra-light Seiko-Epson Flying Robot, weighing just 12.3 g. However, these UAVs have certain drawbacks, including lower flight speed, limited flight endurance, and increased mechanical complexity [1,5]. Hybrid design UAVs can act as fixed-wing as well as rotary-wing UAVs (Figure 1). They combine the vertical flying capabilities of rotary wings and the high speed and long flight duration of fixed wings [7]. However, they are more mechanically complex and have more difficult control. Among them, tilt-rotor UAVs are being researched for their controllability, energy efficiency, and stability. Research on dual tilt-rotors is taking place on the Smart UAV of KARI and BIROTAN, Bell Eagle Eye and the UAV of Universita di Bologna and HARVee [5].

As UAV applications continue to expand, their structural configurations and material choices play a crucial role in optimizing performance. Different UAV types (fixed-wing, rotary-wing, and hybrid), offer distinct advantages and limitations, influencing their suitability for various industries. A comparative analysis of drone types, considering their structure, purpose, applications, materials, and performance, provides valuable insights into how design choices impact operational efficiency and eco-friendliness.

Table 1. Comparative analysis of drone types, structural, aerodynamic, materials used, and performance insights for (a) fixed-wing drones, (b) rotary drones, and (c) hybrid drones.

Drone Type	Drone Structure Detail	Purpose of Study	Application	Modelling and Simulation Software	Material of Drone	Methodology Adopted	Conclusions	Limitations and Future Scope
(a)
Fixed-Wing (eBee and Sky Walker X8) [9]	Airfoils type: MH44, MH45, MH60, MH64, S-5010, and Eh2.0/10.0	Design and analysis of wing section by CFD	Aerial mapping, military, rescue, agriculture	CATIA, SOLIDWORKS, SST k-omega	Expanded polypropylene	2D modeling, numerical drag/lift force calculations	Drag/lift coefficients computed successfully	-
Ranger, TUAV [10]	Frame Dimension: 4.60 × 5.70 × 1.13 m	Aerodynamic behavior and CFD analysis	Surveillance and system assault	ANSYS ICEM, ANSYS CFX	-	CFD analysis at Mach 0.1 and 0.19 numbers	Lift and drag calculations validated	Additional testing on UAV models at different velocities
ATLAS II [11]	Weight: 3.06 kg, Take-off load: 14 kg, Airfoils type: NACA0012, NACA0015	Aerodynamics and flight stability analysis	-	CATIA, ANSA, ANSYS FLUENT	-	Flight mechanics drag coefficient calculations	Successful aerodynamic performance assessment	-
PoliDrone [12]	Weight: 2 kg, Airfoils type: S3A-C, S4A-C, S6A-C, S8A-C	Architecture and performance optimization	Aerial photography, surveillance, inspection	SOLIDWORKS, XcopterCalc, MSC Nastran, and Patran	PLA	Classical lamination theory analysis	Customization enables UAV performance variation	Further analysis of frame mechanical response
Twin Wing-Tail Boom [13]	Max take-off load: 105 kg, Max payload: 20 kg, Flight duration: 3–4 hr	Design and aeroelastic analysis using FEM	High altitude, high-risk areas, combat applications	MSC NASTRAN	Composite	Composite cylinder assemblage modeling	Flexible tail introduced new flutter modes	-
(b)
Quadcopter [14]	Frame Dimension: 24 × 25 × 10 cm	Impact of airflow on frame and propeller	Agriculture, security, medical, inventory	Ansys Fluent, Autodesk Inventor	Propeller: Plastic, Frame: PLA-PLUS	CFD analysis, stress-strain calculations	Deformation issue solved with acrylic reinforcement	-
DJI Spark [15]	Frame Dimension: 101.25 cm × 52.5 × 34.6 cm, Angular velocity: 12,000 rpm	Aerodynamic performance of propellers	Film making, military, mining, logistics	SOLIDWORKS, SIMSCALE, SST k-omega turbulence model	-	Computation domain setup, mesh refinement	Winglet design increases thrust at the same speed	Noise level measurement for propeller blade designs
DJI Phantom 3 [16]	Rotor dia.: 240 mm, Angular velocity: 9549.9 rpm	Ground proximity effect and obstacle interaction	Cargo delivery, surface inspection	k-epsilon, ANSYS	-	Boundary conditions applied, mesh generation	Lift increases, drag decreases, forward pitch movement amplified	Broader range of translational velocities required
DJIS900 [14]	Weight: 3.3 kg, Take-off load: 8 kg	Structural investigation using atomistic simulation	Atmospheric pollution detection	GROMACS, NASTRAN	Polystyrene, composites	Molecular dynamic simulations	Weight savings of 7 g per propeller achieved	Further topological optimization needed
Octocopter [17]	Weight: 20 kg, Radius of rotor blade: 230 mm, Rotor velocity: 4500 rpm	Aerodynamic efficiency and CFD analysis	Battlefield surveillance, law enforcement, border patrol	ANSYS FLUENT	-	Reynolds Averaged Navier–Stokes equations	Large rotors improve aerodynamics but lower efficiency	Further optimization of rotor interaction
Syma X8C [18]	Weight: 0.6 kg, Rotor dia.: 240 mm, Angular velocity: 4000 rpm	Simulation of rotor separation distance	Military operations	X-FLOW	-	Lattice Boltzmann Method CFD	Rotor separation significantly affects forces	-
(c)
Tilt-Rotor (Bell Eagle Eye, NUAA tilt-rotor, Panther UAV) [7]	Multiple rotors mounted on tilting shafts or nacelles	Investigate control stability and transition mechanisms	Surveillance, tactical operations, commercial UAVs	MATLAB, Simulink, CFD tools	Composite materials, lightweight alloys	Experimental testing, control law validation, simulation-based analysis	Hybrid UAVs improve flight stability and versatility	Structural complexity, optimization of control strategies
Tilt-Wing (HARVee, AVIGLE, Greased Lightning VTOL Drone, DHL Parcelcopter) [7]	Partial or entire wing tilts along with rotors	Study aerodynamic performance and transition robustness	Parcel delivery, cargo transport, research UAVs	MATLAB, Simulink, wind tunnel analysis	Carbon fiber, polymer-based materials	Aerodynamic analysis, control mechanism testing, flight trials	Tilt-wing UAVs offer good aerodynamic efficiency but face stability issues	Crosswind vulnerability, refining transition mechanisms
Rotor-Wing (THOR, X-50 DragonFly, NRL Stop-Rotor Aircraft) [7]	Rotary wing that spins for lift and stops for cruise	Explore feasibility of stop-rotor transition technology	Advanced aviation concepts, experimental UAVs	Navier–Stokes solvers, Computational Fluid Dynamics (CFD)	High-strength composites, carbon fiber	Hybrid modeling, wind tunnel testing, prototype development	Rotor-wing UAVs require further research for stable flight transition	High complexity, need for robust transition control strategies
Dual-System (HADA, Quadcruiser, Arcturus JUMP, Hybrid Quadcopter) [14]	Two sets of propulsion systems for vertical and cruise flights	Enhance mechanical simplicity and reliability	Military and civilian hybrid UAV applications	Flight simulation tools, CFD analysis	Lightweight metals, hybrid composites	Comparative analysis, aerodynamic testing, flight validation	Dual-system UAVs show promise but need optimization for efficiency	Additional weight, optimizing aerodynamic drag
MTT (Mono Thrust Transitioning) (SkyTote, Flexrotor, V-Bat) [7]	Single rotor at nose or rear side for thrust generation	Improve stability and efficiency of stall-and-tumble maneuver	Reconnaissance, remote monitoring	MATLAB, gain-scheduling control models	Ducted-fan composite, lightweight polymers	Simulation-based flight control validation, experimental testing	MTT UAVs face stability issues but show potential for optimized control	Unstable vertical flight, needs robust control algorithms
CTT (Collective Thrust Transitioning) (T-Wing, VD200, SUAVI) [7]	Single or multiple fixed-pitch non-cyclic blade rotors	Analyze aerodynamic control for forward flight	Military and industrial applications	MATLAB, nonlinear controllers, backstepping approach	High-performance composites, reinforced polymers	Hybrid modeling, dynamic inversion techniques, adaptive control	CTT UAVs provide efficient forward flight but require enhanced control mechanisms	Difficult landing, needs better tail landing mechanisms
DTT (Differential Thrust Transitioning) (ATMOS-UAV, VertiKUL, Google Project Wing) [7]	Rotors installed above and below the horizontal plane for transition	Develop improved transition techniques using differential thrust	Scientific exploration, experimental UAV research	MATLAB, quaternion-based control simulations	Aerodynamic composite materials	Mathematical modeling, differential thrust validation, experimental trials	DTT UAVs offer simplified control but face aerodynamic inefficiencies	Reduced efficiency in horizontal flight, needs better differential thrust modeling

a–c summarizes these key characteristics, highlighting research methodologies, material choices, and performance trends across various UAV types.

The comparative analysis in Table 1a–c highlights how UAV designs and material choices are shaped by their intended applications, aerodynamic requirements, and structural demands. While early UAVs primarily relied on aluminum and other metals for their structural framework, the shift toward lightweight composite materials has significantly enhanced drone efficiency and performance. As UAV applications continue to grow, the demand for high-stiffness, low-weight materials have become increasingly critical for improving flight endurance, payload capacity, and overall energy efficiency.

Traditionally, aluminum alloys were favored for UAV construction due to their excellent strength-to-weight ratio and durability. However, advancements in polymer composites—such as carbon fiber-reinforced polymers (CFRP), Kevlar^®, and glass fiber composites—have enabled significant weight reduction, improved fuel efficiency, and enhanced structural integrity. More recently, research has turned toward bio-based and recycled materials, aiming to balance high-performance requirements with environmental sustainability [19].

Despite these advancements, most existing studies on UAVs focus primarily on aerodynamics, propulsion, and operational performance, with limited emphasis on the environmental impact of materials. While some of the literature explores UAV materials in isolation, there is a lack of comprehensive reviews integrating material selection with sustainability metrics, including energy consumption, carbon footprint, and end-of-life recyclability. Furthermore, LCA studies on UAVs remain scarce, particularly those that systematically compare the trade-offs between mechanical properties and ecological impact. This gap in research highlights the need for a holistic approach to UAV material selection that accounts for both performance efficiency and environmental responsibility. This review aims to address these gaps by:

• Section 3→Examining materials used in UAV construction, including metals, polymers, and composite materials.
• Section 4, Section 5 and Section 6→Evaluating the environmental impact of these materials through LCA, focusing on energy consumption, emissions, and recyclability.
• Section 7→Identifying emerging sustainable alternatives that balance structural efficiency with a reduced ecological footprint.

By integrating mechanical performance analysis with sustainability considerations, this study provides a framework for optimizing UAV material selection, supporting the transition toward more energy-efficient and environmentally responsible drone manufacturing.

2. Methodology

This review systematically evaluates UAV material selection through a comprehensive literature analysis. Relevant studies were sourced from Scopus, Web of Science, and Google Scholar, using keywords related to UAV materials, composites, eco-friendliness, and LCA. From an initial 307 screened articles, 67 were selected based on empirical data, UAV material properties, performance, and environmental impact.

To maintain data quality, only peer-reviewed journal articles, conference proceedings, and technical reports published in the last two decades were included. Studies lacking empirical data or material characterization were excluded. The review compares traditional metals (aluminum, titanium), polymers (ABS, polycarbonate), and fiber-reinforced composites (CFRP, Kevlar^® (registered trademark of DuPont, Wilmington, DE, USA), glass fiber) based on mechanical properties, weight efficiency, and durability. Additionally, emerging materials such as bio-based composites and recycled carbon fibers are assessed for their potential to reduce UAV environmental impact.

The environmental impact analysis utilizes existing LCA studies, focusing on energy consumption, carbon footprint, and recyclability. Comparative LCA metrics highlight trade-offs between high-performance composites and alternative materials. The study follows a three-tiered approach:

(1)

UAV Material Selection and Structural Performance

• Examines traditional materials (metals, polymers, composites) and emerging alternatives like bio-based composites, hybrid laminates, and recycled carbon fibers.
• Evaluates mechanical properties such as stiffness-to-weight ratio, impact resistance, fatigue performance, and corrosion resistance.

(2)

Environmental Impact Assessment Using LCA

• Follows ISO 14040 guidelines with a cradle-to-grave approach covering material extraction, manufacturing, operational use, and disposal.
• Quantifies energy consumption and emissions, discussing material recovery, disposal, and recyclability challenges.
• Uses Monte Carlo simulations and sensitivity analyses to model uncertainty and variability in LCA data.

(3)

Optimizing UAV Material Selection

• Applies Multi-Criteria Decision Making (MCDM) to rank materials based on recyclability, emissions, and energy demand.
• Explores probabilistic vs. deterministic modeling for improved UAV material assessments.
• Highlights future challenges, such as integrating aerodynamic performance into LCA models and advancing UAV material circularity.

3. Materials Used for UAV Construction

Since UAVs require lightweight and high-stiffness materials to enhance flight efficiency and payload capacity, aluminum was initially the preferred choice for their construction due to its favorable stiffness -to-weight ratio [20]. However, with advancements in materials science, composite materials have increasingly replaced aluminum, particularly in load-bearing components such as elevators (elevators on an aircraft’s tail control pitch, adjusting nose position to regulate altitude during flight), which contribute approximately 20% of an aircraft’s total weight. The adoption of composites for critical structures like wings, tail sections, and fuselage has resulted in significant weight reductions, improving aerodynamic efficiency and fuel economy. Among composite materials, thermosetting polymers are more commonly used than thermoplastics due to their superior fiber impregnation capability, which facilitates the manufacturing of complex, high stiff structural components. Epoxy resins are the most widely used thermoset due to their excellent low-temperature resistance (<93 °C), meaning they perform optimally and maintain their properties below this temperature. Above this threshold, they may begin to soften, degrade, or lose mechanical integrity. Also, epoxy resins offer high chemical stability, strong fiber adhesion, dimensional stability, and superior performance in humid environments. Other thermosetting resins used in UAV applications include polyesters, phenolics, bismaleimides, and polyimides.

In contrast, thermoplastics, such as polyethylene and polystyrene, offer advantages like recyclability, improved toughness, and rapid processing. However, they are generally less common in UAV structures due to the superior heat resistance and structural rigidity of thermosets. High-performance thermoplastics like polyetheretherketone (PEEK), polyimides, and PPS, however, are exceptions, as they offer excellent thermal stability and are used in advanced aerospace applications. Reinforcement fibers play a crucial role in enhancing the mechanical properties of composites. The most widely used fibers include carbon, graphite, Kevlar^®, and glass fibers. Among these, carbon and Kevlar^® fibers dominate UAV applications due to their high stiffness-to-weight ratio and excellent impact resistance. Glass fibers, although cost-effective, are typically used in civilian UAVs rather than military-grade drones due to their lower strength and stiffness. Ceramic and metallic fibers are rarely used, as they increase structural weight and add complexity to the design.

The introduction of composite materials has provided UAVs with numerous advantages beyond weight reduction, such as improved fatigue resistance, corrosion resistance, and design flexibility, as summarized in

Table 2. Advantages and disadvantages of using composites over metals for building UAVs [21].

Advantages of Composites	Disadvantages of Composites
Lightweight—Enables better flight efficiency, increased payload capacity, and lower energy consumption.	High Cost—Manufacturing and raw materials (e.g., carbon fiber) are more expensive than metals.
Corrosion Resistance—Composites are immune to rust and oxidation, unlike metals.	Difficult to Recycle—Most thermoset composites cannot be easily reprocessed, unlike metals such as aluminum.
High Fatigue Resistance—Long lifespan under cyclic loading, reducing maintenance frequency.	Impact Sensitivity—Brittle behavior under hard landings or collisions, leading to micro-cracks.
Design Flexibility—Can be molded into complex aerodynamic shapes with reduced assembly requirements.	Complex Manufacturing—Requires specialized fabrication methods like autoclave curing or resin transfer molding (RTM).
Reduced Radar Signature—Some composites have low radar reflectivity, beneficial for stealth applications.	Thermal Limitations—Degrades under high temperatures; needs special coatings for heat resistance.
High Strength-to-Weight Ratio and Stiffness-to-Weight Ratio—Provides structural efficiency superior to most metals.	UV and Moisture Sensitivity—Some composites degrade when exposed to prolonged sunlight or humidity.
Low Thermal Expansion—Enhances dimensional stability in varying temperatures, useful for UAVs in high altitudes.	Bonding Challenges—Composite-to-metal bonding can be unreliable, requiring advanced adhesive techniques.

. These factors have driven a shift from metal-based UAV structures to advanced fiber-reinforced composites, enabling superior performance, durability, and sustainability in modern UAV design [21].

Several nations have increasingly adopted composite materials for UAV construction due to their superior stiffness-to-weight ratio, durability, and corrosion resistance. For example, Israel’s Orlite UAV incorporates a combination of reinforced polyester, epoxy, glass fiber, graphite, phenolic resins, and aramid composites to enhance structural performance and reduce weight [21]. Similarly, the University of Sydney’s UAV Brumby utilized carbon fiber/Kevlar^® fiber composites to manufacture the main gear of the undercarriage, optimizing both lightweight efficiency and mechanical strength [21]. In the commercial UAV sector, Parrot, a company founded by Henri Seydoux in 1994, has pioneered advancements in polymer-based drone structures. In 2010, it introduced the AR. Drone, a quadcopter remotely piloted via Wi-Fi using a smartphone and equipped with an embedded camera. This section provides a detailed analysis of materials used in UAV construction, categorizing them based on their application in structural components, aerodynamic surfaces, and functional parts.

3.1. External Skin and Body

The first version of Boeing’s X-45A Unmanned Combat Aerial Vehicle (UCAV) featured an aluminum internal structure combined with an external skin made of low-radar-profile carbon composite, as reported by the Aeronautical Development Establishment of the Indian Ministry of Defense. This hybrid construction provided structural stiffness while reducing radar cross-section, a crucial factor in stealth UAVs. Similarly, the University of Sydney’s UAV Brumby incorporated a sandwich composite fuselage made of glass fiber/Nomex^®(registered trademarks of DuPont, Wilmington, DE, USA) fiber, offering high stiffness, strength, and lightweight characteristics, making it well-suited for aerial applications requiring structural efficiency. The Global Hawk UAV, a long-endurance reconnaissance drone, primarily utilizes aluminum for its fuselage, ensuring durability and manufacturability. However, to optimize weight and performance, key components such as the tail assembly and engine nacelles are constructed using composite materials, balancing mechanical resilience with weight reduction for extended flight operations [21]. A smaller and lighter version of UAV, named Flapping Wing Micro Aerial Vehicle (MAV), was inspired by flying birds and insects to achieve flying skills similar to an existing plane. The body was made from Styrofoam, which is light weight, impact resistant, and easy to fabricate [22]. The Sabanci University unmanned aerial vehicle (SUAVI) is an electric-powered UAV with quad tilt-wing. It has long flight durations like an airplane and can take vertical takeoff and landings like a helicopter. Its prototype was built using carbon composite material for the body to have lightweight and stiffness against flight and landing forces [5]. Junk et al. [23] reported the use of ABS material for the preparation of cowlings the engine bonnet of the UAV, as shown in Figure 2.

Parrot has continued to lead innovation in civilian drone technology, launching the Bebop 2 in 2015, which featured a structure composed of injected glass-fiber-reinforced polyamide-based composite. The evolution of Parrot’s UAVs further expanded with the Bebop 20, whose body and arms were manufactured by CRP Technology using Laser Sintering and Windform^® (trademark of CRP Technology, Modena, Italy)GT Additive Manufacturing material [24]. Windform^® GT, a glass-fiber-reinforced polyamide-based composite, is recognized for its high mechanical performance, durability, and aesthetic quality. The material exhibits a smooth, deep-lustrous finish after hand polishing and offers a unique balance of flexibility and stiffness, making it particularly suitable for additive manufacturing applications in UAV production. The 3D-printed body frame and arms of the UAV are shown in Figure 3 [24]. Neimend et al. [25] developed a foldable 3D-printed UAV from recycled PETG plastic filament. Tubul et al. [26] developed an electric glider which uses a motor to reach desired location and altitude, then glides freely for a certain period with the motor switched off. The glider was built using Kevlar^® reinforced epoxy composite and the finished product was coated with fine microglass.

In electric gliders, the motor is primarily used to achieve the desired altitude or position before transitioning into a gliding phase, where the aircraft operates without engine power for an extended period. This design maximizes energy efficiency by leveraging aerodynamics for sustained flight with minimal power consumption. For structural fabrication, Kevlar^® reinforcement is placed within a predefined mold and infused with epoxy resin to enhance stiffness and durability. The mold is then subjected to a vacuum process to remove air pockets, ensuring optimal fiber adhesion and structural integrity. Finally, the assembly undergoes heat curing for several hours, allowing the composite material to achieve high stiffness and impact resistance. Figure 4 illustrates the design and key components of the glider, detailing its aerodynamic configuration and material composition [26]. Cetinsoy et al. [5] developed the Sabanci University unmanned aerial vehicle (SUAVI) prototype with a carbon composite body, which provided a lightweight yet structurally robust framework capable of withstanding flight loads and landing impacts. To further enhance mechanical strength and structural integrity, a carbon composite pipe chassis was incorporated as the UAV’s backbone, ensuring improved durability and resistance to aerodynamic stresses.

The UAV by Özöztürk [13] consists of the fuselage skin made up of Kevlar^®, E-glass, and carbon fabric composites. In some places the skin is reinforced with longitudinal stringers built from foam core and composite fabric facings. Figure 5 shows the fuselage structure of the UAV [27]. Valyou et al. [28] reported the fuselage structure of UAV made from fiberglass and epoxy composite laminate consisting of a 3 mm Rohacell^® (registered trademark of Evonik Industries, Essen, Germany) core reinforcement between fuselage frames. A 6 mm carbon composite/Rohacell^® laminate secured with panel bonding adhesive were used for nose and main landing gear bulkhead. A 13 mm thick carbon composite/Nomex^® honeycomb laminate are used for the firewall and firewall brace. Bateman et al. [29] used sandwich core construction for the semi-monocoque construction for the fuselage. The fuselage consists of aluminum extrusion, covered with a Coroplast skin. Çalışır et al. [30] developed a Hydra UAV consisting of Computer Numerical Control (CNC)-formed expanded polystyrene (EPS) forming the main fuselage of the UAV. The fuselage’s lower part is reinforced with glued carbon fiber fabric.

3.2. Propeller Materials

For large UAVs, propellers must exhibit high stiffness and durability to withstand aerodynamic loads and ensure efficient flight performance. Borchardt [21] recommended the use of synthetic fiber reinforcement over a laminated wood core to enhance structural integrity and longevity. Initially, glass and Kevlar^® fiber-reinforced epoxy resins were employed; however, modern propeller designs increasingly utilize carbon semi-stressed fiber-reinforced epoxy over laminated wood, offering improved stiffness-to-weight ratio and fatigue resistance. These composite propellers contribute to stable flight performance, optimizing airfoil shape and blade efficiency for enhanced lift, rapid climb, and extended service life. However, laminated wood-based propellers suffer from poor resistance to rain erosion, necessitating protective urethane tapes on leading edges as a short-term solution. A more durable approach involves inlaid urethane resin edges, which improve both aerodynamics and erosion resistance. Additionally, applying epoxy or urethane resins to the entire propeller further enhances durability and surface protection. A more advanced alternative is the use of fully synthetic propellers, manufactured from carbon/glass fabric impregnated with high-temperature epoxy resin, providing superior mechanical properties and environmental resistance. Furthermore, bonded nickel erosion shields have been proposed for composite propellers, offering additional protection against wear and extending operational lifespan. Ramesh et al. [31] selected a glass-fiber-based composite (Epoxy E-Glass-UD) as a suitable material for UAV propeller, providing high structural performance at all the critical environments. Wisniewski et al. [32] developed small 3D-printed propellers from VeroWhite ABS and Accura Xtreme Gray(3D Systems, Rock Hill, SC, USA). The materials showed low noise footprint and good efficiency.

3.3. Wings and Tails

The first versions of Boeing’s X-45A UCAV had its wing built around a core of lightweight foam matrix. However, for using UCAVs at high speeds (12–15 Mach) and for accommodating high mechanical stresses and thermal loads associated with maneuvering, ceramic/metal composites and metal matrix composites are used more commonly [21]. The University of Sydney’s UAV Brumby was initially designed with foam core wings covered in plywood and glass fiber. However, these have since been replaced with glass/Nomex^® resin composites, offering enhanced stiffness, durability, and weight reduction. Similarly, the ScanEagle UAV, originally constructed using a combination of aluminum and composites, has transitioned to lightweight carbon fiber composites in its latest iterations, significantly improving aerodynamic efficiency and structural performance. The Global Hawk UAV, known for its long-endurance reconnaissance capabilities, features long-span wings reinforced with four I-beam spars made of carbon/epoxy composite. Additionally, its wing leading and trailing edges utilize Nomex^® aramid honeycomb-cored sandwich laminates, providing high stiffness-to-weight efficiency and excellent impact resistance [21]. Chanzy and Keane [33] developed wings out of glass-fiber-clad polystyrene foam with selective laser sintered (SLS)-nylon 3D-printed inserts acting as ribs, all supported on carbon-fiber spars. The FEA model of the wings, as shown in Figure 6, consists of several key components. The foam skin is represented in white, while the SLS nylon male sliders are depicted in red, and the SLS nylon female sliders in green. The SLS nylon normal ribs are shown in blue, whereas the nylon rib designed for the servo appears in light pink. Additionally, the carbon fiber-reinforced epoxy spar, which provides structural reinforcement, is illustrated in beige [33].

Figure 7 shows the control surface diagram. To decrease the turbulent airflow from the wing to the control surface, the fiberglass matrix extensions are used [34]. The wing structure in the UAV by Felício et al. [35] consisted of 2 mm thick ribs of balsa wood, wing skin of 240 g/m² carbon fiber/epoxy, and 22 mm carbon circular tube spar. Epoxy impregnated carbon fiber was used to make rack-guide tube. An I-beam was made from a set of two carbon stringers and the balsa wood web to increase stiffness and bending strength with minimum gain in weight.

The UAV by Özöztürk et al. [13] consisted of lower and upper wing skins made of a composite sandwich structure having aircraft grade Rohacell^® 31A9 (Evonik Industries, Essen, Germany) foam material between woven E-glass layers. All parts of the wing skin were made of foam core to help improve skin buckling resistance and resist side loads because of minor impact loads or the loads during transportation. The front spar root end was made from hornbeam wood, and the rear spar root was made from aluminum. The front spar box is built from carbon-epoxy composite. The color-coded zones of the wing are shown in Figure 8.

The horizontal and vertical tail of the UAV by Özöztürk et al. [13] has its internal structure similar to the internal structure of the wing. Sandwich structure consisting of Rohacell^® foam as the core material with E-glass woven fabric composite as the face sheets forms the skins of the tail. The Rohacell^® foam as the core material in the skin was used to eliminate the ribs in the horizontal and vertical tails. The presence of Rohacell^® foam core in the sandwich structure provides good stiffness to the skin and prevents side buckling and penetration due to side loads. Figure 9 shows the internal structure of the horizontal and the vertical tail.

The wings of the electric glider developed by Tubul et al. [26] were made of Balsa core, Fiberglass (skins). The UAV by Valyou et al. consists of wings and control surfaces made up of Rohacell^® core with fiberglass/epoxy laminate, ribs made with carbon fiber/Rohacell^® laminate, and a woven carbon fiber roll/wrapped spar tube. The main tail and spar were made with commercial roll-wrapped carbon fiber composite tubes which are light weight and easily available. The bulkheads were made up of carbon fiber sandwich panels due to their light weight, good stiffness, and strength. The bulkheads, ribs and braces and reinforcing panels apart from the firewall have Rohacell^® core panels. The firewall instead was made from a panel with a Nomex^® honeycomb core to help give additional thickness and stiffness in the stressed area. Sections of wing, and tail skins were reinforced as a sandwich panel [28]. Bateman et al. [29] used sandwich core construction for the wings. The wings consisted of Coroplast covering the EPS foam core and stiffened by a composite plywood and aluminum spar. The tail surface was made entirely from Coroplast panels, stiffened inside the flutes with carbon fiber rods. The Hydra UAV by Çalışır et al. [30] is of balsa wood, with its surface covered with coating paper. The wings are made from EPS covered with coating paper.

3.4. Support Frame

The multicopter prototype by Anweiler and Piwowarski [36] used commercially available plastic PA66 GF 30 and E-glass epoxy laminated for its framework. This material combination provided durable and rigid structure. The framework thus obtained had high strength and stiffness, and the arm could not break or bend easily. Bateman et al. [29] developed a UAV consisting of a monitor aluminum space-frame structure as its foundation for the load bearing truss type framework, which could be partially covered or fully covered by a flexible lightweight material. The sandwich core construction is used for designing a hybrid space frame. According to the Aeronautical Development Establishment of the Indian Ministry of Defense [21], its UAV has a laminated glass/carbon-reinforced fiber airframe. The SUAVI consists of a backbone made from carbon composite pipe chassis which is provides support to the wings and fuselage skin [5]. The UAV prototype by Denning [34] is made from balsa wood and plywood and fiberglass matrix in a cured resin. Giannakis and Savaid [37] used the concept of multi-layered composites to achieve a structurally integral and lightweight airframe. GG285P(T700)-DT120-40, GG300P(T800)-DT120-40, PVC foam, Al honeycomb, Nomex^® honeycomb were the selected composite material for the designing of the airframe.

Table 3. Materials and monotonic mechanical properties [37].

Material	Density (tn/m3)	Tensile Strength (MPa)	Tensile Modulus (GPa)
GG285P(T700)-DT120-40	1.57	800	67
GG300P(T800)-DT120-40	1.57	850	67
PVC foam	0.075	1.89	0.075

shows the properties of the materials used, and Figure 10 shows the UAV and its structural layout [37]. Morerira et al. [38] selected the frame of the generic model F450 UAV made from high-strength nylon for the construction of its UAV.

Table 4. UAV materials categorization based on their application in structural components.

Component	Commonly Used Materials	Key Properties	Advantages of Using These Materials for This Component	Disadvantages of Using These Materials for This Component	UD/Weave/Stacking Sequence	Matrix	Core
Fuselage	Carbon Fiber Composites, Kevlar®, Glass Fiber Composites, Aluminum	Lightweight, High Stiffness, Impact Resistant, Fatigue Resistant	Enhances UAV durability, reduces weight for improved efficiency, absorbs impact well, resists fatigue failure	High cost of composites, complex manufacturing processes, and challenging repairs if structural damage occurs	Unidirectional (UD) and woven fabrics	Epoxy	N/A
Wings	Carbon Fiber Composites, Glass Fiber/Nomex® Resin, Foam Core Composites, Aluminum	Aerodynamic Efficiency, High Stiffness-to-Weight Ratio, Durability	Optimizes lift-to-drag ratio, improves efficiency, reduces weight while maintaining strength	Expensive materials, complex to manufacture, and prone to micro-cracking under repeated stress	Woven fabric, Quasi-isotropic layup	Epoxy	Foam Core
Tail	Carbon Fiber Composites, E-Glass Epoxy, Rohacell® Foam, Aramid Honeycomb	Structural Stability, Lightweight, Resistance to Buckling and Impact	Provides stability in flight, resists deformation under aerodynamic loads, lightweight construction improves control	Difficult to manufacture, prone to delamination if not properly bonded	Woven and Sandwich stacking	Epoxy	Rohacell® Foam, Aramid Honeycomb
Propellers	Carbon Fiber-Reinforced Epoxy, Glass/Kevlar® Fiber Reinforced Epoxy, Laminated Wood Core	High Stiffness, Long Service Life, Rain and Impact Resistance	Enhances aerodynamics, reduces energy consumption, provides durability for extended operational life	Vulnerable to erosion (especially in rain and debris impact), expensive materials, requires maintenance	UD fiber orientations	Epoxy	Laminated Wood Core
Support Frame	Carbon Composite Pipe Chassis, High-Strength Nylon, Aluminum	Structural Integrity, Load Distribution, High Strength	Provides strong foundation for UAV, reduces weight while maintaining structural integrity, minimizes vibrations	Expensive materials, complex to assemble, potential joint weaknesses if not properly reinforced	UD and Woven	Thermoplastic and Epoxy	N/A
External Skin	Low-Radar-Profile Carbon Composites, Glass Fiber/Nomex® Resin, Polyamide-based Glass Reinforced Composites	Lightweight, Radar Absorption, Corrosion Resistance	Improves stealth properties (low radar cross-section), corrosion-resistant, resists environmental degradation	Difficult to repair, high production costs, UV degradation over time	Quasi-isotropic layup	Epoxy	Nomex® Honeycomb
Internal Structure	Aluminum, Carbon Fiber Composites, Epoxy Resin Composites	High Load-Bearing Capacity, Structural Rigidity, Impact Resistance	Provides strong internal framework, withstands flight loads, ensures overall UAV structural stability	Heavier compared to composite alternatives, metals are prone to corrosion if not treated	Woven fabric layup	Epoxy	N/A

categorizes UAV materials based on their application in structural components, aerodynamic surfaces, and functional parts. The table includes common materials used, key properties, advantages, and disadvantages for each component.

4. Life Cycle Assessment

LCA quantitatively evaluates the environmental impact of UAV materials, guiding energy-efficient selection while ensuring structural integrity. Unlike traditional assessments, LCA offers a holistic view—considering raw material extraction, manufacturing, operational efficiency, and end-of-life treatment. For UAVs, where lightweight composites dominate, LCA helps balance high-performance carbon materials with sustainable alternatives like recycled carbon fibers (rCF) and bio-based composites.

Cradle-to-gate assessment is crucial for UAV manufacturing, analyzing energy-intensive processes such as fiber synthesis, resin infusion, and composite curing. Meanwhile, cradle-to-cradle is key for rCF recovery through pyrolysis or solvolysis, reducing embodied energy. Additionally, thermoplastic-based matrices enhance recyclability, allowing modular reuse and extended material lifespans in UAV structures.

The life cycle inventory (LCI) in UAV LCA quantifies energy use, CO₂ emissions, and material waste across production, operation, and disposal. Virgin carbon fiber (~350–500 MJ/kg) has high environmental costs, while rCF cuts energy demand by ~75%, making it a viable alternative. Bio-based composites, though lower in embodied energy, require synthetic fiber hybridization to meet mechanical strength needs. Carbon fiber CO₂ emissions vary by energy grid, with hydroelectric-based regions emitting less than fossil-fuel-dependent areas. However, its high energy demand remains a concern, highlighting the need for process innovations and cleaner energy sources.

Process-based LCA, commonly employed in aerospace composites, captures detailed material and energy flows and waste streams, highlighting inefficiencies in high-temperature curing and resin waste. In contrast, economic input-output LCA can model large-scale UAV fleet deployment scenarios, quantifying cumulative environmental burdens. However, both approaches require validated datasets—a significant challenge given the rapid advancements in UAV materials and manufacturing technologies. Efforts to improve and communicate LCI data quality in the LCA community have led to several methodologies. Key semi-quantitative methods include the pedigree matrix, which has been refined over time, notably in its integration into the Ecoinvent database, as well as the data quality ranking system developed within the ILCD framework. Additionally, the European Union introduced the Product Environmental Footprint (PEF) methodology, building upon the ILCD approach, while the United States Environmental Protection Agency (US EPA) later introduced an updated version of the pedigree matrix method [39].

Ultimately, a multi-criteria LCA approach, integrating material efficiency, recyclability, and energy intensity, is necessary to transition UAV manufacturing toward low-impact, high-performance materials. This approach ensures that structural optimization does not come at the cost of sustainability, supporting the development of next-generation UAVs with minimal ecological footprint while preserving flight endurance and mechanical integrity.

The LCA method is now being used to examine the sustainable development in the aviation sector and compare the sustainable delivery of goods and services. The aviation industry primarily contributes to greenhouse gas emissions through the combustion of fossil fuels during flight operations, significantly impacting climate change. While fuel dumping before emergency landings also releases unburned hydrocarbons, its overall environmental impact is comparatively lower than the emissions generated from continuous fuel combustion. Hence LCA is being used to evaluate the whole life cycle of aerial vehicles from their production and till it is disposed of [40]. A review of LCA in the aviation industry is already been reported in the literature [40,41], while a review on LCA for the assessment of the sustainability of drones is reported by Mitchell et al. [42]. Bachmann et al. [41] reported the LCA of eco-materials, focusing on bio-based fibers, recycled carbon fibers and bio-based thermosets. They discovered a literature gap with use case of bio-based and recycled materials. Çalışır [40] reported limited literature related to environmental impacts of vehicle, tools, services and processes in aviation sector. They suggested taking the landing, take-off, and cruise phases into consideration for fuel consumption [40]. Mitchell et. al. [42] reported a literature gap related to part production, reliable data in LCA studies, the end-of-life phase, and health and social impacts due to drone usage. Literature gaps were also reported related to detailed parts production process and were absent for composites. The review concluded that there is dependency and relationship between functional unit, operational model and frame of operation.

The LCA of Hydra UAV is done to assess the environmental impacts of the two different power groups used in the UAV. The first power group consisted of an electric motor, a lithium polymer battery, and a propeller, while the second hybrid power group was formed by the addition of a Proton Exchange Membrane (PEM) fuel cell. The cradle-to-grave LCA method was implemented using SimaPro 9.1 software and Ecoinvent 3.6 database. Impacts on global warming, terrestrial ecotoxicity, photochemical oxidation, acidification, and eutrophication were analyzed. The LCA showed that use of hydrogen fuel resulted in reduction of terrestrial ecotoxicity and global warming [30]. Erdman and Mitchum [43] developed life cycle cost modelling for UAV used for national security boats, US Coast Guard Force, and offshore patrol ships. They used US coast guard cost data and performed the LCA on Microsoft excel software. The LCC analysis tool developed was helpful in assisting the Coast Guard’s unmanned aircraft system (UAS) program management team. Figliozzi [44] compared the CO₂e and energy emission efficiency of UAV with that of commercial ground vehicles for the delivery of goods. For small payloads, UAVs were more CO₂e efficient than conventional diesel vans. On grouping a few customers, tricycle or electric van delivery services were more CO₂e efficient than UAV. Comparing disposal emissions per delivery and vehicles production, ground vehicles were more efficient. Neuberger [45] reported the environmental effects of a commercial UAV. The use of UAV technology for supplementing or replacing delivery vehicles was analyzed. The LCA was focused on the manufacturing and operational phases. The gate-to-gate LCA methodology was used using data from Ecoinvent and performing the analysis on SimaPro software. The environmental impacts on climate change, human toxicity, and water, fossil, and metal depletion were discussed. The efficient use of UAV as delivery vehicles is highly dependent on the location of the delivery. The largest impact was produced due to the production of electronic parts and batteries. Automation of UAV assembly could change production phase energy. Leighton performed LCA to study the implementation of DJI Phantom 3 UAV for infrastructure inspection. The LCA method of gate-to-grave was performed using the software SimaPro 8.04.30 with TRACI 2.1 and a database from Ecoinvent. The UAV was found to be more sustainable than aerial surveying technologies as well as the conventionally ground site surveys performed by a team of professionals [46].

5. LCA of UAV Following ISO 14040 Framework

This study follows the ISO 14040 framework to ensure a comprehensive and methodologically sound assessment, adopting a cradle-to-grave approach that covers raw material extraction, manufacturing, operational use, and end-of-life disposal.

5.1. Goal and Scope Definition

The goal of this LCA study is to evaluate and compare the environmental impacts of manufacturing UAV structural components using different materials and composite systems. The study specifically assesses the trade-offs between energy consumption, carbon footprint, and recyclability of UAV materials. Key objectives include:

• Comparison of energy utilization in the manufacturing of UAV structural components using different materials/composites.
• Assessing the trade-offs between mechanical performance and environmental impact of various UAV materials.
• Quantification of the environmental impact of different UAV materials in terms of energy demand (MJ/kg), carbon footprint (kg CO₂-eq/kg material), material recyclability (%), and end-of-life treatment.
• Provide recommendations for UAV material selection.

This study is intended for UAV manufacturers seeking sustainable material choices, material scientists researching eco-friendly composites, aerospace and sustainability policymakers establishing environmental regulations for UAVs, and researchers and academics developing next-generation UAV materials.

This study supports the transition toward low-carbon UAV manufacturing, assists in eco-design decisions by selecting materials with lower environmental impact, and provides baseline comparative data for future UAV LCA studies.

The scope of the study defines the system boundaries, methodological choices, and assumptions that govern the LCA approach. The product system under study includes UAV structural components such as the fuselage (main body structure), wings and tails (load-bearing aerodynamic structures), propellers (thrust-generating components), and the support frame and landing gear (structural reinforcements).

The functional unit of the study is defined as “the environmental impact of 1 kg of UAV structural material over 1000 flight hours”. This ensures that the results are normalized, allowing for direct comparison of different materials while accounting for their performance in real-world UAV applications. The cradle-to-grave approach includes raw material extraction (mining and processing of aluminum, carbon fiber, Kevlar^®, and other UAV materials), material production and manufacturing (composite curing, metal forming, injection molding, and assembly processes), energy use in manufacturing (energy demand for material processing and UAV part fabrication), operational energy use (UAV energy consumption during flight, including battery charging emissions), and end-of-life treatment (landfilling, recycling, or incineration of UAV materials). Certain elements are excluded from this LCA, including minor components such as screws, fasteners, and electronic sensors, as well as software and operational control systems. Maintenance and repair processes beyond standard material replacements are also not considered.

For this study, a medium-sized commercial UAV designed for logistics and surveillance applications was analyzed. The drone under assessment is a quadrotor UAV with a payload capacity of 2 kg, a maximum flight time of 45 min, and an operational range of 10 km per charge. Its structural frame is composed of CFRP due to its high stiffness-to-weight ratio, while aluminum alloy is used for mounting components and reinforcement. The propellers are made of PC, and hybrid-wing versions incorporate Kevlar^®–glass composites. The drone is powered by a high-energy-density lithium-ion battery pack (800 Wh capacity) charged via conventional electric grids (national energy mix for India).

5.2. Life Cycle Inventory (LCI) Analysis

The LCI analysis follows ISO 14044 (Clause 4.3.3), compiling data on UAV materials, energy consumption, and environmental impact based on a cradle-to-grave approach. This study relies entirely on secondary data sources, including literature reviews, life cycle inventory datasets, and product catalogs. Given the variability in sources, assumptions are made to address data gaps, and uncertainties in calculated LCIs are considered. The inventory analysis consists of collecting data on material type, total material weight, fiber/matrix ratios for composites, material extraction and production energy consumption, and manufacturing energy consumption.

The study relies exclusively on secondary data sources, as no direct manufacturer specifications or flight tests were conducted. Secondary data sources include well-established LCI databases such as Ecoinvent, SimaPro, and GREET, along with published research papers and technical reports on UAV materials and sustainability. Data quality considerations ensure temporal coverage of the past 10 years to maintain relevance, geographical scope from global sources focusing on UAV industries, and uncertainty analysis, where Monte Carlo simulations are used to quantify uncertainty in LCI data.

The study assesses a variety of UAV materials, including expanded polystyrene (EPS), polycarbonate (PC), polyethylene terephthalate (PET), high-strength nylon, aluminum alloys, carbon fiber-reinforced composites, Kevlar^®, and fiberglass composites, with manufacturing processes such as injection molding, vacuum-assisted resin transfer molding (VARTM), extrusion, pultrusion, and 3D printing. The collected data for UAV materials, their respective input weights, and manufacturing processes are detailed in

Table 5. Basic data for UAV parts.

Parts	Material	Input Weight (gm)	Manufacturing Process	Refs.
FWUAV-Body and wings	EPS	1050	Injection moulding	[45]
MRUAV-body + legs + Propellers	PC	175 + 42 + 35 = 252	Injection moulding	[45]
GANEFLY MAV wing, Tail, and Body	Styrofoam	0.76 + 1.20 + 0.92 = 2.88	Injection moulding (assumed)	[22]
Cowling	ABS	284 × 262 × 141 mm (dimension)	−	[23]
RPA frame	High-strength nylon	282	Extrusion (assumed)	[38].
RPA propellers	Plastic ABS	10 × 4.5 inches (dimension)	Injection moulding (assumed)	[38].
Base and Top Plate + Rotor Arms (x4) + Canopy	PET	39.88 + 111.52 + 38.7 = 190.1	Printing (78 h 25 min)	[25]
Body 1700 mm	Kevlar®, Microglass, Fiberglass, epoxy	Total weight 3800 (1266 estimate)	VARTM	[26]
Wing 3400 mm	Balsa core, Fiberglass	3800 (2533 estimate)	VARTM	[26]
Propeller + Frame	−	10 + 500 = 510	−	[47]
Frame:	Aluminium Alloy	−	−	[48]
Propeller:	Nylon (30% assumed), glass fiber (60%), carbon fiber (10% assumed) (APC 1047)	100–300	Pultrusion process	[48]

. Energy consumption for material extraction, production, and manufacturing is compiled in

Table 6. Energy consumption for drone parts.

Parts	Materials	Extraction and Production Energy (MJ/kg)	Manufacturing Process	Manufacturing Energy (MJ/kg)	Total Energy per kg (MJ/kg)	Ref.
Body	EPS	90	Injection Moulding	19	109	[45]
	PC	112.95			131.95	[45]
	PET	82.71
Frame	Aluminium	226.5	−	−	−	[48]
	Nylon	157.65	Injection moulding	19	176.65	[38,49]
	Polyester	70.5			89.5	[50]
	Polystyrene	94.5			113.5	[50]
	CFRC	−	RTM	−	701	[51]
Propellors	PC	112.95	Injection Moulding	19	131.95	[45]
	Composite (Nylon (30% assumed), glass fiber (60%), carbon fiber (10% assumed) (APC 1047)	157.65, 22.5, 78	Pultrusion process	3.1	87.34	[48,49,51,52,53]
	Carbon fiber-reinforced composites	−	RTM	−	701	[51]
	ABS	105	Injection Moulding	19	124	[38,54]

, where the total energy per kilogram of material is calculated as the sum of extraction and production energy along with manufacturing energy. The highest energy demands are observed for carbon fiber-reinforced composites (701 MJ/kg) and aluminum (226.5 MJ/kg), while lower energy-consuming materials include polystyrene and polyester.

Certain assumptions and limitations apply to the study. Manufacturing energy data for UAV materials is derived from comparable industrial processes when direct LCA data is unavailable. End-of-life scenarios are modeled based on current recycling efficiencies, with alternative scenarios exploring potential improvements over time. Battery charging impacts are estimated based on regional energy grid mixes (coal, renewable, nuclear) as UAV operational emissions depend on energy sourcing.

Since direct greenhouse gas (GHG) emissions and recyclability rates are not explicitly detailed in the dataset, energy consumption values serve as a proxy for estimating emissions in Life Cycle Impact Assessment (LCIA). The end-of-life scenarios for UAV materials vary, with metals such as aluminum being highly recyclable, whereas CFRP and Kevlar^® pose significant challenges due to limited recycling options. Some manufacturing processes were assumed based on material properties (e.g., extrusion for high-strength nylon, pultrusion for composite propellers), and where direct LCI data was unavailable, values were extrapolated from similar aerospace and automotive processes. The uncertainties in literature-derived LCI data will be addressed in the LCIA phase using sensitivity analysis and Monte Carlo simulations to assess how variations in assumptions impact overall environmental outcomes.

5.3. Life Cycle Impact Assessment

This study applies LCIA following ISO 14044 (Clause 4.4) to quantify the environmental burdens associated with UAV materials. The assessment focuses on key impact categories, including climate change (carbon footprint), cumulative energy demand (CED), resource depletion, human toxicity potential, and end-of-life recyclability. Impact categories are characterized using IPCC GWP100 for climate change, while energy demand is assessed in megajoules per kilogram (MJ/kg) from extraction to disposal. Normalization and weighting techniques are not applied, ensuring transparency in comparing materials based on available environmental impact data.

The energy consumption per kilogram for UAV materials varies significantly, as detailed in Table 6. Hybrid composites exhibit the lowest energy demand due to their optimized fiber–matrix ratio, balancing structural performance and sustainability, whereas CFRPs require up to 700 MJ/kg due to energy-intensive pyrolysis and autoclave curing [54]. While thermoplastics (PC, PEEK) and thermosets (epoxy, phenolics) fall within an intermediate energy footprint range, their recyclability remains a key factor in material selection. Thermoplastics enable reprocessing and modular UAV designs, while thermosetting resins, despite higher mechanical stability, pose significant recycling challenges. Despite CFRPs’ high initial energy cost, their low weight reduces in-flight energy consumption, potentially improving UAV efficiency by 6–8% for every 10% weight reduction, leading to proportional reductions in fuel or electric power consumption over the UAV’s operational life.

The cradle-to-grave analysis evaluates the energy consumption, emissions, and material disposal impacts across UAV materials. CFRP production requires high-temperature carbonization, significantly increasing energy demand (~500–700 MJ/kg) [55]. Aluminum extraction is highly energy-intensive due to electrolysis (226.5 MJ/kg), but its 95% recyclability rate mitigates some of its environmental burden [56]. PC propellers require lower energy input (19 MJ/kg for injection molding) but contribute to fossil fuel-derived plastic waste, increasing landfill accumulation [57]. Among manufacturing processes, CFRP exhibits the highest energy demand (50 MJ/kg) due to autoclave curing and resin infusion, making it one of the most energy-intensive UAV materials [58]. Aluminum requires 30 MJ/kg for casting and extrusion, but its high recyclability makes it a preferable material despite the initial energy investment [59]. PC propellers, while energy-efficient in production, have a shorter lifespan, leading to frequent replacements and increased material waste [60].

Total greenhouse gas (GHG) emissions per UAV flight depend on battery energy consumption and the energy mix used for charging. A coal-based grid (820 g CO₂/kWh) results in emissions of 5.25 kg CO₂ per full flight cycle, whereas a wind-powered grid (12 g CO₂/kWh) limits emissions to 0.076 kg CO₂ per flight [61]. Battery degradation over time further influences UAV energy efficiency and material waste, as lithium-ion batteries typically last 500 charge cycles before replacement, contributing to electronic waste concerns [62]. The battery pack typically lasts 500 charge cycles before needing replacement, after which improper disposal can result in the toxic leaching of lithium, cobalt, and nickel into the environment [63]. Only 5% of lithium-ion batteries are fully recycled globally, emphasizing the need for improved battery recovery systems [64].

Resource depletion and toxicity impacts vary by material. Aluminum, while highly energy-intensive (226.5 MJ/kg) during extraction, offsets its impact with a 95% recyclability rate [48]. In contrast, CFRP and Kevlar^® composites pose significant challenges due to limited end-of-life recovery options [58]. The environmental trade-offs in thermochemical recycling of CFRP through pyrolysis offer potential solutions, as recovered carbon fibers retain partial mechanical integrity. Additionally, bio-based composites incorporating flax and hemp fibers present a promising alternative to petroleum-derived resins, reducing both energy consumption and disposal impact.

This study emphasizes the importance of sustainable material selection, highlighting that hybrid composites, bio-based alternatives, and recycled CFRPs provide viable solutions for reducing UAV energy consumption and environmental impact. A modular UAV design approach could further extend operational lifespans, reduce waste, and promote circular economy principles. Future research should explore detailed disposal modeling, recycling efficiency improvements, and end-of-life UAV decommissioning scenarios to provide a more comprehensive sustainability assessment.

5.4. Interpretation of Results (ISO 14044, Clause 4.5)

The findings are presented through structured comparative assessments. While no formal critical review was conducted under ISO 14044 Clause 6, data reliability is ensured through secondary sources such as Ecoinvent, SimaPro, and peer-reviewed literature. The results are visualized using comparative material analysis charts, sensitivity analysis, and Pareto frontier evaluations, providing actionable insights for sustainable UAV material selection.

5.4.1. Comparative Energy Consumption and Carbon Footprint of Materials

Figure 11 presents a comparative analysis of various UAV components based on material selection, energy consumption during extraction and manufacturing, and recyclability. The UAV frame is primarily constructed using aluminum or CFRP. Aluminum, with a total energy consumption of 256.5 MJ/kg and a high 95% recyclability rate, is a more sustainable choice. In contrast, CFRP requires 751 MJ/kg, making it far more energy-intensive, with a significantly lower recyclability rate of 30%, despite its high stiffness-to-weight ratio. For propellers, PC is a more environmentally friendly option, consuming 131.95 MJ/kg with an 80% recyclability rate, compared to CFRP, which mirrors its high energy demand of 751 MJ/kg and low recyclability of 30%. This suggests that while CFRP enhances UAV performance, it comes at a substantial environmental cost. Similarly, for body materials, EPS offers a good balance between low energy consumption (109 MJ/kg) and moderate recyclability (60%), making it a practical choice. Wings can be made from Kevlar^®–glass or balsa–carbon composites. Kevlar^®–glass is more energy-intensive (595 MJ/kg) with a recyclability rate of 40%, while balsa–carbon wings have a lower energy consumption of 420 MJ/kg and a better recyclability rate of 60%, making them a more sustainable alternative. Overall, the data suggests that aluminum, PC, EPS, and balsa–carbon composites are more sustainable options for UAV construction, as they balance performance with lower energy demand and higher recyclability. CFRP, while offering excellent mechanical properties, remains the least sustainable choice due to its excessive energy consumption and poor recyclability.

Figure 11 highlights the CO₂ emissions associated with various UAV materials, which is an important factor in assessing their environmental impact. CFRP stands out with the highest CO₂ emissions at 31.4 kg CO₂/kg, followed by Kevlar^®–glass composites at 22.8 kg CO₂/kg. These materials, while offering high stiffness-to-weight ratios, come with a significant carbon footprint due to their energy-intensive production processes. Balsa–carbon composites and aluminum have moderate emissions, with balsa–carbon contributing 18.5 kg CO₂/kg and aluminum emitting 11.5 kg CO₂/kg. Aluminum’s production is energy-intensive, but its high recyclability helps mitigate its environmental impact, making it a relatively sustainable choice. On the other hand, EPS and PC are the most environmentally friendly materials based on GHG emissions and climate change impact, with EPS emitting only 3.0 kg CO₂/kg and PC emitting 5.2 kg CO₂/kg. These materials are especially useful for non-structural UAV components where lower strength requirements allow for the use of lighter, more sustainable options. In conclusion, EPS and PC are the most sustainable in terms of CO₂/kg emissions, while CFRP and Kevlar^®–glass present greater environmental challenges due to their higher emissions.

5.4.2. Sensitivity Analysis and Multi-Criteria Decision Making (MCDM)

The sensitivity analysis on UAV materials follows several key steps. First, a baseline scenario is established by defining the current material compositions and their associated environmental impacts. Next, parameter variation is conducted, specifically reducing the use of CFRP in UAV frames and propellers by 20%, replacing it with aluminum or hybrid composites. Impact measurement involves recalculating the energy consumption and carbon footprint of the adjusted material composition. These results are then subjected to a comparative evaluation to assess the effect of reducing CFRP on overall sustainability and performance. The analysis also includes trade-off considerations, where the benefits of a reduced carbon footprint are weighed against potential performance losses, such as increased weight. Finally, validation ensures the accuracy of the analysis by comparing the findings with experimental or simulated UAV flight performance data. The findings of the sensitivity analysis indicate that a 20% reduction in CFRP usage, replaced by aluminum, can lower the carbon footprint by nearly 18%, though this comes at the cost of slight performance degradation. Hybrid materials like recycled CFRP or flax–carbon composites are suggested as a balanced solution, offering a compromise between stiffness and sustainability. Furthermore, lightweighting strategies, such as structural optimization using finite element analysis (FEA), can mitigate performance losses when switching to more sustainable materials. Looking ahead, several trends in UAV materials show promise for improving sustainability. Recycled carbon fiber is highlighted as an alternative to virgin CFRP, reducing overall energy input by up to 40%. Bio-based resins, derived from plant-based polymers, offer a more sustainable matrix for composites. Graphene-infused composites can enhance stiffness while potentially lowering weight, although their recyclability remains a challenge. Additionally, additive manufacturing (3D printing) is gaining traction as a method to reduce waste by optimizing component production layer by layer. The sensitivity analysis underscores the potential for enhancing UAV sustainability through material optimization, the adoption of hybrid materials, and the development of recycling strategies. Future UAV designs should prioritize bio-based materials and lightweight hybrid composites, while leveraging advanced recycling techniques and modular designs to improve lifecycle environmental considerations.

5.4.3. Advanced Sensitivity Analysis: Monte Carlo Simulations

To account for uncertainties in material properties, manufacturing processes, and operational parameters, we employed Monte Carlo simulations (Figure 12). This stochastic method allows for a comprehensive assessment of potential variability in the LCA outcomes. The Monte Carlo simulation process begins by defining input parameters, such as energy consumption, material properties, manufacturing efficiencies, and emission factors, which are identified as key variables in the model. Next, probability distributions are assigned to each parameter based on their characteristics, such as using a normal distribution for manufacturing energy consumption and a uniform distribution for material efficiencies. The simulation is then executed, running 10,000 iterations where random samples are drawn from the assigned distributions to simulate a range of possible outcomes. Finally, the result analysis involves interpreting the simulation results, including calculating the mean, standard deviation, and confidence intervals for the total energy consumption and emissions. The findings from the Monte Carlo simulations revealed that the total carbon footprint varied between 28.5 and 35.2 kg CO₂-equivalent per flight hour, with a 95% confidence interval, indicating a range of potential outcomes based on the uncertainties in the input parameters. The analysis also showed that energy consumption was most sensitive to CFRP processing inefficiencies, highlighting the significant impact that production methods have on the overall environmental performance of the UAV, particularly in relation to CFRP usage.

5.4.4. Scenario Analysis: Impact of Energy Grid Mix

Figure 13 highlights the significant impact of different energy sources on UAV carbon emissions. The figure visually represents the UAV emissions per flight when powered by these sources. The data reveals that the choice of energy mix plays a crucial role in determining the carbon footprint of UAV operations. Coal is the most carbon-intensive energy source, emitting 820 g CO₂ per kWh, which translates to approximately 5.25 kg CO₂ per UAV flight. This high level of emissions makes coal the least sustainable option for powering UAVs. Natural gas, while cleaner than coal, still produces significant emissions at 450 g CO₂ per kWh, resulting in 2.88 kg CO₂ per flight. These figures emphasize that fossil fuel-based energy grids contribute substantially to UAV-related carbon emissions. In contrast, renewable energy sources offer a much cleaner alternative. Solar power, with emissions of 50 g CO₂ per kWh, leads to a significantly lower UAV emission rate of 0.32 kg CO₂ per flight. Wind energy is the cleanest among all sources, emitting only 12 g CO₂ per kWh, corresponding to a mere 0.08 kg CO₂ per flight. Hydropower also presents a low-emission option at 24 g CO₂ per kWh, leading to 0.24 kg CO₂ per flight. These numbers underscore the vast difference between fossil fuels and renewables in terms of environmental impact. The comparison between the table and the figure makes it clear that shifting to renewable energy sources is essential for reducing UAV carbon footprints. Wind energy stands out as the most environmentally friendly option, followed by solar and hydropower.

Additionally, Figure 13 illustrates the energy consumption associated with the extraction and manufacturing of different UAV materials. The materials analyzed include aluminum, CFRP, PC, and Kevlar^®–glass. Energy consumption is divided into two categories: extraction energy (in orange) and manufacturing energy (in red), measured in megajoules per kilogram (MJ/kg). Among the materials, CFRP exhibits the highest total energy consumption, with an extraction energy of 701 MJ/kg and a manufacturing energy of 50 MJ/kg. This makes it the most energy-intensive material in the chart. Kevlar^®–glass follows with a total energy consumption of 595 MJ/kg, consisting of 550 MJ/kg for extraction and 45 MJ/kg for manufacturing. These values suggest that CFRP and Kevlar^®–glass, despite their desirable lightweight and high-stiffness properties, come at a high environmental and energy cost. Aluminum, on the other hand, has significantly lower total energy demand compared to CFRP and Kevlar^®–glass. Its extraction energy is 226 MJ/kg, with an additional 30 MJ/kg required for manufacturing. While still energy-intensive, it is a more sustainable option than CFRP. PC has the lowest overall energy consumption, with an extraction energy of only 113 MJ/kg and a minimal manufacturing energy of 19 MJ/kg, making it the least energy-demanding material in comparison. CFRP and Kevlar^®–glass offer superior mechanical properties, but their high energy consumption may pose environmental challenges. In contrast, aluminum and PC provide lower energy footprints, making them more energy-efficient alternatives. To optimize UAV design for environmental considerations, a balance must be struck between performance requirements and energy efficiency in material selection.

Figure 14 illustrates a Pareto frontier analysis for UAV materials, assessing the trade-off between environmental considerations and mechanical performance. The x-axis represents the carbon footprint in kg CO₂ per kg of material, indicating the environmental impact, while the y-axis shows the strength in MPa, representing the material’s mechanical capability. The goal is to identify materials that offer an optimal balance between these two competing factors. The blue crosses indicate different UAV materials, each labeled accordingly. Materials positioned toward the left of the plot have a lower carbon footprint, making them more sustainable, while those positioned higher on the plot possess greater mechanical strength. For example, EPS and PC exhibit low carbon footprints but also have relatively low strength. In contrast, CFRP provides the highest strength but at a significantly higher environmental cost.

The red dashed line represents the Pareto frontier, which connects materials that offer the best possible trade-offs between environmental considerations and performance. The Pareto frontier graph evaluates UAV material selection, balancing strength (MPa) vs. carbon footprint (kg CO₂ kg). Materials lying on this frontier are Pareto-optimal, meaning that no other material in the dataset offers a better combination of both properties. These materials include EPS, PC, aluminum, balsa–carbon, Kevlar^®–glass, and CFRP, each providing a unique balance of stiffness and environmental considerations. Materials that do not lie on this line are dominated options, meaning there exists another material with either higher strength at the same or lower carbon footprint or lower carbon footprint at the same or higher strength. From an engineering and material selection perspective, the figure provides valuable insights. If environmental considerations is the primary concern, materials like EPS or PC are preferable due to their low carbon footprint. If performance is the dominant criterion, CFRP is an ideal choice, albeit with a high environmental impact. However, intermediate materials like balsa–carbon and Kevlar^®–glass offer reasonable compromises, delivering moderate stiffness with a controlled environmental footprint. This Pareto frontier visualization aids in multi-objective decision-making for UAV material selection. By identifying materials that lie on the frontier, engineers can make informed choices that best align with design requirements, whether emphasizing environmental considerations, performance, or a balance of both.

The forecasting model (Figure 14) aims to predict future trends in UAV carbon footprint by analyzing advancements in materials, energy sources, and manufacturing techniques. One key factor is the introduction of recycled composites and bio-based materials, which can significantly reduce lifecycle emissions. Additionally, the transition of the energy grid toward renewables will play a crucial role, as more UAVs rely on clean energy sources for charging. Innovations in low-energy fabrication techniques are also expected to reduce emissions associated with UAV manufacturing. By examining historical trends in material selection and energy use, the model forecasts the evolution of UAV carbon emissions over the next 20 years. Using time-series forecasting methods such as LSTM and ARIMA, the study predicts that the average UAV lifecycle carbon footprint will decrease from 28.5 kg CO₂ in 2025 to 12.3 kg CO₂ by 2045, representing a 57% reduction. This decline is primarily driven by the adoption of recycled CFRP and thermoplastic composites, the decarbonization of the energy grid, and the development of lighter UAV structures, which improve flight efficiency. Material innovations will have a profound impact on carbon reduction. If recycled CFRP replaces virgin CFRP, lifecycle emissions can drop by 30%. Additionally, the use of flax–fiber composites, which are bio-based, further reduces environmental impact. Aluminum and hybrid composites also improve recyclability by 50%, significantly lowering emissions during manufacturing. The UAV energy mix is expected to transition from a coal-dominated charging infrastructure to a renewable-based system. Coal-powered UAV charging, which accounts for 60% in 2025, is projected to decline to just 10% by 2045, while wind and solar energy adoption is expected to rise to 70%. This transition alone will reduce operational emissions by 90%, making clean energy integration a crucial factor in achieving sustainability goals. Battery technology advancements will further contribute to emission reductions. The adoption of solid-state batteries is expected to enhance UAV efficiency by 40%, reducing overall energy consumption per flight. Additionally, the development of higher life cycle batteries will minimize waste and lower material demand, contributing to a more sustainable UAV ecosystem. The implications of these forecasts highlight important actions for industry stakeholders. Manufacturers should prioritize the use of recycled CFRP and thermoplastics to align with the industry’s shift toward sustainability. Energy policymakers must accelerate the transition to clean UAV charging grids to support net-zero aviation goals. Meanwhile, researchers should continue focusing on bio-based and graphene composites to further push emission reductions beyond 2045.

Figure 15 presents the flow of resources, energy, and emissions across the UAV lifecycle, emphasizing Figure 15 critical inefficiencies and sustainability challenges. The horizontal axis represents the progression from raw material extraction to manufacturing, operation, and end-of-life stages. The vertical spread indicates the relative scale of resource inputs, energy consumption, emissions, and waste generation at each stage, with larger sections reflecting greater contributions to environmental impact. Circular economy pathways, such as recycling, are distinguished from landfill disposal to highlight material recovery potential. The visualization highlights the significant energy consumption during raw material extraction and manufacturing, reinforcing that upstream processes account for a major portion of the total environmental footprint. This indicates that material efficiency strategies, such as reducing raw material dependency through recyclability improvements or adopting alternative lightweight materials, could significantly mitigate environmental impact.

Figure 15 also underscores the energy losses associated with battery charging and operational flight, clarifying that UAV emissions are not only dependent on fuel or electricity consumption but also on charging efficiency and grid energy sources. The distinction between fossil-fuel-based electricity and potential renewable energy inputs suggests that decarbonization of energy sources could be a key intervention to reduce UAV lifecycle emissions. Furthermore, the disproportionate losses from power conversion and storage inefficiencies highlight the need for advancements in battery technology, energy storage optimization, and UAV power management systems. A crucial insight from this figure is the clear differentiation between recycled materials and landfill waste, illustrating that despite the presence of recycling pathways, a substantial proportion of UAV materials still end up as non-recovered waste. This distinction reinforces the necessity of improving material circularity, strengthening recycling infrastructure, and advancing UAV design for disassembly to facilitate material recovery. Additionally, the structured mapping of emissions pathways across different lifecycle stages provides a comprehensive view of carbon output distribution, demonstrating that environmental considerations improvements must address both production-phase emissions and end-of-life material recovery.

The structured representation in Figure 15 goes beyond traditional LCA frameworks by offering an integrated approach to identifying intervention points, ranging from sustainable material selection and enhanced recyclability to energy efficiency improvements and cleaner operational power sources. This analysis supports the need for holistic UAV design strategies that optimize material and energy flows to minimize environmental impact throughout the system’s lifecycle. At the end-of-life stage, only 30% of UAV materials are successfully recycled, while the remaining 70% ends up as landfill waste. This indicates that current recycling efforts are insufficient to close the material loop, underscoring the importance of developing better recycling technologies and sustainable disposal practices to minimize waste accumulation. Additionally, energy losses in battery charging and flight propulsion systems account for nearly 25% of the total UAV lifecycle energy use. These inefficiencies arise from thermal losses, power conversion, and propulsion system limitations, suggesting that advancements in battery technology and propulsion efficiency could significantly reduce overall energy consumption and improve the environmental considerations of UAVs.

5.4.5. Optimized UAV Material Selection Results (Genetic Algorithm Analysis)

The genetic algorithm (GA) was used to find the best combination of materials for UAV manufacturing by optimizing for high structural stiffness (ensuring performance and durability), low weight (reducing overall mass for better flight efficiency), and minimal carbon footprint (improving environmental considerations and reducing lifecycle emissions). The genetic algorithm evolved the following materials (

Table 7. Selected materials for optimization.

Component	Selected Material	Strength (MPa)	Weight (kg/m2)	Carbon Footprint (kg CO2/kg)
Frame	Aluminum	310	2.7	11.5
Propeller	PC	75	1.2	5.2
Body	EPS	50	0.5	3.0
Wings	Kevlar®–glass	400	1.5	22.8

) as the optimal selection.

The optimization process led to a strategic selection of materials, balancing structural performance, environmental considerations, and recyclability. Aluminum was chosen for the UAV frame due to its favorable strength-to-weight ratio and high recyclability, avoiding the significant carbon footprint associated with CFRP. For the propellers, PC was selected, as it is both lightweight and cost-effective while maintaining the necessary durability. The UAV body was constructed using EPS, primarily due to its low weight and minimal environmental impact, making it a suitable choice for reducing overall energy consumption. Additionally, Kevlar^®–glass composite was used for the wings, offering an exceptional stiffness-to-weight ratio, which enhances aerodynamic performance while maintaining structural integrity. The selected materials contribute to a lightweight UAV design, reducing the total mass and improving both energy efficiency and flight duration. In terms of environmental considerations, the optimization minimizes the UAV’s carbon footprint compared to CFRP-based alternatives. The recyclability of materials like aluminum and PC supports a circular economy, mitigating landfill waste and promoting resource efficiency. Finally, the chosen combination ensures structural stiffness, allowing the UAV to withstand aerodynamic loads and operational stresses, thus enhancing both durability and performance. This optimized material combination provides a technically feasible and environmentally sustainable alternative to traditional CFRP-dominated UAV structures.

Figure 16 presents a sensitivity analysis evaluating the impact of various material properties on UAV environmental considerations. It is a horizontal bar graph where each bar represents a material property, and the length of the bar corresponds to its sensitivity score, indicating the extent to which that property influences UAV environmental considerations. The analysis provides insight into which material characteristics are most critical for improving environmental considerations in UAV design and operation. Material weight has the highest sensitivity score of 0.35, meaning it plays the most significant role in determining environmental considerations. A lighter UAV requires less energy for operation, leading to improved efficiency and reduced environmental impact.

Operational energy use follows closely with a score of 0.30, highlighting that materials influencing energy consumption during flight are crucial for environmental considerations. This suggests that selecting materials that minimize energy requirements can lead to a more sustainable UAV. Manufacturing energy, with a sensitivity score of 0.25, also has a substantial effect, indicating that the energy expended during the production of UAV components is a key consideration. CO₂ emissions, scoring 0.20, reflect the importance of reducing greenhouse gas emissions in material selection. Although recyclability has the lowest sensitivity score of 0.15, it still contributes to environmental considerations, albeit to a lesser extent compared to weight and energy-related factors. In practical terms, the findings suggest that if UAV designers aim to improve environmental considerations, they should prioritize lightweight materials that require less operational and manufacturing energy. While reducing CO₂ emissions and improving recyclability are valuable goals, the most effective way to enhance UAV environmental considerations is through material choices that minimize weight and energy consumption. While this study defines a performance-based functional unit to align with UAV operational requirements, the current assessment is constrained by available mass-based environmental impact data. The study establishes a methodological framework that can be expanded in future research with more refined aerodynamic performance data, enabling more precise material selection based on UAV operational efficiency. Also, while this study evaluates the impact of different energy sources on UAV emissions, the environmental footprint associated with the construction, manufacturing, and installation of renewable energy infrastructure (e.g., wind turbines and solar panels) is beyond the scope of this assessment. Future studies may incorporate these embedded emissions for a more comprehensive energy impact evaluation.

5.4.6. Limitations of the Study

This study relies on secondary data sources, including literature values, LCI databases, and engineering estimates, due to the absence of primary experimental data. As a result, potential variability in results exists, particularly in material energy consumption and emissions estimates. The material impact calculations are based on a mass-per-kilogram approach, which does not account for variations in aerodynamic efficiency and structural optimization in real-world UAV designs, potentially affecting comparability. Additionally, the study does not consider UAV maintenance and repair cycles, meaning energy consumption from component replacements, operational wear, and refurbishment processes is excluded, even though these factors could influence the long-term environmental impact.

A further limitation arises in end-of-life disposal modeling, as UAV-specific recycling efficiencies, landfill emissions, and incineration byproducts are not well-documented in current literature. Due to limited UAV disposal datasets, assumptions were necessary regarding material recyclability and waste treatment pathways, which may not fully reflect real-world UAV decommissioning scenarios.

Additionally, certain technical aspects of UAV LCA methodology were beyond the scope of this review. This study aimed to provide a detailed conceptual framework for UAV LCA, but full-scale process-based modeling, dynamic LCI variations, and economic cost-benefit analysis of sustainable UAV materials were not within the review’s scope. The study does not integrate multi-objective optimization approaches for UAV material selection, nor does it quantify the environmental benefits of advanced recycling technologies such as thermochemical depolymerization and closed-loop CFRP recovery systems. Furthermore, supply chain emissions, transportation logistics for UAV components, and battery degradation modeling were not explicitly considered, as these aspects require a more system-specific, real-time operational dataset beyond what is available in current literature.

This study does not include the amortization of capital equipment used in UAV material production and manufacturing, as it falls outside the defined cradle-to-grave system boundary. The environmental burdens assessed in this LCA focus on material extraction, processing, manufacturing energy consumption, operational emissions, and end-of-life disposal, rather than long-term industrial infrastructure impacts. Although a full LCA compliant with ISO/TR 14047:2003 requires that acidification, eutrophication/nitrification, human and eco-toxicity, depletion of resources, stratospheric ozone depletion, and photooxidation formation be considered, these parameters were not assessed.

Existing aerospace and UAV LCA literature indicates that capital equipment amortization typically contributes less than 1% to total environmental burdens, making it insignificant compared to energy-intensive processes such as carbon fiber production (~700 MJ/kg) and aluminum extraction (~226.5 MJ/kg). Additionally, the LCI datasets used in this study (Ecoinvent, SimaPro, GREET) do not incorporate capital equipment depreciation at the process level, further supporting its exclusion. While future studies could explore the life cycle impact of UAV manufacturing infrastructure, the current study aligns with standard ISO 14040-compliant LCA practices, where capital amortization is generally omitted unless industrial infrastructure impacts are explicitly within the study’s scope.

Despite these limitations, this study provides a structured, technical overview of UAV LCA, serving as a foundation for future research. To enhance accuracy, future studies should incorporate empirical UAV life cycle data, operational flight energy measurements, and advanced sensitivity analyses to further refine sustainability assessments in UAV design and manufacturing.

6. Alternative Approach to LCA Complimenting Previous Findings

The LCA of UAV materials presented in the previous section establishes a fundamental evaluation of environmental impact based on literature-derived data. While this approach provides an essential baseline, it relies on fixed values and does not fully account for variations in material processing or a structured ranking system to assess trade-offs between different environmental considerations metrics. To refine the conclusions, an alternative approach using Monte Carlo-based uncertainty analysis and MCDM was implemented. This computational methodology introduces a systematic material selection framework while ensuring that conclusions are based on a probabilistic rather than deterministic understanding of environmental impact. In this alternative approach, an LCI was first compiled by integrating data on extraction energy, manufacturing energy, carbon footprint, and recyclability for key UAV materials. These values were cross-referenced with those in the previous section to ensure consistency while allowing for additional refinements [52,53,54]. The Monte Carlo simulation was then applied to model uncertainty in material impact by introducing statistical variability in energy consumption and emissions across 10,000 iterations. This method accounts for variations in industrial processing conditions and ensures that the reported values are not singular estimates but instead represents a range of probable environmental impacts. The analysis reveals that while general sustainability trends remain unchanged, the exact environmental burden of certain materials, particularly composites, fluctuates depending on process efficiency and sourcing. Unlike the previous section, which focuses on reporting specific impact values, this approach emphasizes the stochastic nature of environmental impact and provides a confidence interval around material sustainability metrics, allowing for more robust assessment. The variability in energy consumption and emissions observed in this simulation is illustrated in Figure 17, which highlights how different materials exhibit distinct levels of uncertainty in their environmental footprint.

To further enhance material selection, MCDM was introduced to establish a structured decision-making framework. While the previous section qualitatively discusses the environmental considerations of different UAV materials, it does not assign explicit trade-offs between competing environmental factors such as energy demand, emissions, and recyclability. The MCDM approach applied weighted factors to these three criteria, integrating them into a single sustainability ranking. The structured ranking methodology ensures that material selection is not solely based on individual impact metrics but instead considers the combined environmental footprint of each material in a way that reflects realistic design constraints. This enhances the previous LCA findings by translating material impact assessments into actionable insights for UAV component selection. The ranking results from the MCDM analysis, presented in Figure 18, clearly demonstrate that PC and EPS outperform CFRP and Kevlar^®–glass in terms of environmental considerations, reinforcing the argument for adopting these materials in UAV manufacturing.

A significant distinction between the uncertainty modeling in this approach and that in the previous section lies in the scope of probabilistic assessment. While both analyses employ Monte Carlo simulations, the previous section applies this technique primarily to UAV operational energy use and emissions over a flight cycle. In contrast, this approach focuses on uncertainty in the manufacturing phase of UAV materials, offering a complementary perspective on sustainability considerations. This distinction is important because while operational impact assessments help evaluate the environmental footprint of a UAV throughout its lifecycle, material selection must be driven by a cradle-to-gate perspective, where the environmental costs of production are a determining factor. By combining these perspectives, a more comprehensive environmental considerations assessment emerges, ensuring that materials are evaluated not only for their long-term environmental effects but also for their manufacturing and supply-chain feasibility. The broader range of environmental variability in CFRP, particularly in fiber production and resin processing, is further visualized on Figure 19, where Monte Carlo simulation results illustrate the impact of different material production scenarios.

The deeper technical insight provided by this approach also highlights the sensitivity of CFRP’s environmental footprint to manufacturing inefficiencies. The results indicate that variations in fiber production methods, resin curing techniques, and material processing contribute significantly to its final energy consumption and emissions. Unlike materials such as aluminum and PC, whose impact remains relatively stable across different scenarios, CFRP exhibits a wider range of possible environmental burdens. This insight suggests that improving manufacturing efficiency and waste recovery strategies for CFRP could lead to meaningful reductions in its sustainability deficit. Similarly, while the recyclability of materials is often treated as a fixed property, the Monte Carlo approach shows that end-of-life impact is highly dependent on collection and processing rates, which can fluctuate significantly depending on regional policies and technological advancements. These findings emphasize the need for dynamic modeling in sustainability assessments, where material properties are not treated as static but instead are analyzed under a range of possible real-world conditions.

The MCDM approach applied weighted factors to these three criteria, integrating them into a single sustainability ranking. The structured ranking methodology ensures that material selection is not solely based on individual impact metrics but instead considers the combined environmental footprint of each material in a way that reflects realistic design constraints. This enhances the previous LCA findings by translating material impact assessments into actionable insights for UAV component selection. The final sustainability ranking, as shown in Figure 20, confirms that PC and EPS emerge as the most viable materials due to their favorable balance of low energy demand, minimal emissions, and moderate recyclability. Aluminum remains a strong alternative for structural UAV components due to its high recyclability, even though it has moderate energy consumption and emissions. Conversely, CFRP consistently ranks the lowest due to its high environmental burden across all assessed parameters. This structured ranking system ensures that material selection decisions reflect holistic sustainability considerations rather than isolated impact factors.

The integration of statistical variability analysis and decision-based ranking refines the conclusions of the previous section by strengthening the material selection process. Rather than replacing the existing LCA findings, this approach extends them by adding a quantitative dimension to sustainability decision-making, ensuring that the UAV material selection process is both data-driven and adaptable to process variations. This enhanced framework makes it possible to optimize UAV material selection not only for immediate environmental impact reduction but also for long-term sustainability improvements based on advancements in manufacturing efficiency, material recovery, and recycling technologies. Weight is a critical factor in UAV material selection, directly impacting flight endurance, payload capacity, and energy consumption. While this ranking is based on weight, these factors inherently influence drone performance. However, future research may expand the ranking by incorporating additional parameters such as stiffness-to-weight ratio, aerodynamic efficiency, and mechanical durability.

7. Emerging and Less Common UAV Materials: Potential and Limitations

The previous section provides a detailed evaluation of widely used UAV materials; however, several other materials exist that have not been extensively discussed due to their limited adoption, insufficient LCA data, or performance trade-offs that restrict their feasibility for UAV applications. Among these are magnesium alloys, which offer an excellent stiffness-to-weight ratio and could serve as alternatives to aluminum. However, their susceptibility to corrosion necessitates protective coatings, which increase production complexity and environmental impact. Their recyclability is also lower compared to aluminum, making them less favorable for UAV structures exposed to variable environmental conditions. Natural fiber composites, such as flax or hemp-reinforced polymers, have gained attention as sustainable substitutes for synthetic composites like CFRP and Kevlar^®–glass. These materials exhibit lower embodied energy and a reduced carbon footprint, yet they suffer from lower mechanical strength, poor moisture resistance, and variability in fiber properties, limiting their suitability for UAV structural applications. Additionally, large-scale data on their long-term durability and compliance with aviation safety standards remains lacking, making it difficult to integrate them into a quantitative sustainability assessment.

Another category of emerging materials includes graphene-reinforced polymers, which offer exceptional stiffness, electrical conductivity, and lightweight characteristics. While these properties present exciting possibilities for UAV development, graphene-enhanced composites remain in the experimental phase, facing challenges related to high production costs, scalability, and supply chain constraints. Furthermore, their environmental impact, particularly regarding energy-intensive manufacturing processes and end-of-life disposal, remains largely unquantified, preventing their inclusion in comparative LCA. Bio-based resins, derived from renewable plant sources, are being explored as alternatives to petroleum-based epoxy resins in CFRP and Kevlar^® composites. These resins could improve biodegradability and reduce dependency on fossil fuel-derived materials, aligning with sustainability goals. However, their mechanical performance limitations, processing challenges, and the early stage of an established industrial supply chain hinder their viability for UAV applications where structural reliability is critical. Variability in raw material sourcing and curing properties further complicates their integration into high-performance UAV components.

Additional unconventional materials, such as titanium alloys and shape-memory alloys, have been explored in UAV applications, particularly in aerospace and defense sectors. Titanium alloys offer superior strength and corrosion resistance but come at a high cost and increased density, making them impractical for lightweight UAV designs where fuel efficiency is prioritized. Shape-memory alloys, which can adapt to environmental changes and offer self-healing capabilities, are being investigated for advanced UAV morphing structures, but their current applications remain experimental and costly. Similarly, aerogels and metal matrix composites have demonstrated potential in thermal insulation and high-stiffness applications, but their scalability, manufacturing complexity, and uncertain LCA data make them unsuitable for widespread UAV adoption at present.

The exclusion of these materials from the detailed discussion in the previous section is justified by their limited industrial use, insufficient life cycle datasets, or practical barriers that restrict their commercial viability in UAV manufacturing. While these materials present promising avenues for research and future sustainability improvements, their current limitations in processing efficiency, cost, and performance consistency make their adoption in UAV applications uncertain. Further advancements in material processing techniques, cost reduction strategies, and regulatory approvals will be necessary before these materials can be systematically included in UAV LCA assessments.

8. Comparative LCA of UAVS Across Applications: A Material-Centric Perspective

LCA studies on UAVs vary significantly depending on their application, operating conditions, and mission-specific requirements. While previous research primarily focuses on the operational efficiency of UAVs in sectors such as logistics, agriculture, surveillance, and defense, fewer studies emphasize the role of material selection in defining the overall environmental footprint. This section integrates existing LCA findings across different UAV applications, linking them to material sustainability, performance trade-offs, and recyclability. Delivery drones, commonly powered by lithium-ion (Li-ion) batteries, experience frequent charge–discharge cycles, resulting in significant battery degradation and e-waste concerns. Their frame structures are often made from CFRPs or lightweight aluminum alloys, prioritizing energy efficiency. Studies indicate that the carbon footprint of UAV-based deliveries is lower than traditional delivery trucks over short distances; however, when factoring in battery production and disposal, the environmental advantage diminishes. The dominant environmental contributors in drone-based logistics include battery resource extraction (e.g., lithium, cobalt, nickel) and carbon fiber manufacturing, both of which have high embodied energy.

In contrast, surveillance drones, often operating over extended periods without carrying payloads, exhibit longer operational lifespans with fewer charge cycles, reducing battery replacement frequency. However, military-grade surveillance UAVs, such as fixed-wing drones, integrate titanium, advanced composite materials, and reinforced polymers, which have a high energy-intensive manufacturing process. While these materials improve durability and reduce mid-life maintenance, their production phase contributes significantly to carbon emissions, water use, and toxic byproducts [65].

Agricultural drones, which support precision farming, crop monitoring, and pesticide spraying, are subject to chemical exposure, UV radiation, and humidity, influencing material degradation. Most off-the-shelf commercial UAVs use CFRP and thermoplastic composites, which are prone to wear when exposed to fertilizers and agrochemicals. While glass fiber composites (GFRPs) offer better chemical resistance, they have higher density and lower strength-to-weight ratios than CFRPs, leading to increased energy consumption during operation. Bio-based composites, such as natural fiber-reinforced polymers (NFRPs), show promise in agricultural UAVs due to their biodegradability and resistance to UV-induced embrittlement. However, challenges related to moisture absorption and reduced mechanical properties currently limit their widespread adoption [66].

Defense UAVs require stealth, high-stiffness materials, and thermal resistance, often employing aramid-reinforced composites, radar-absorbing coatings, and titanium alloys. These materials, while crucial for stealth and impact resistance, exhibit high embodied energy and complex recycling pathways. Additionally, thermoset-based CFRPs, which are commonly used in defense UAVs, have limited recyclability compared to thermoplastic composites. Recent advancements in self-healing polymer composites and recyclable epoxy resins offer potential solutions to mitigate environmental concerns while maintaining high-performance structural integrity.

A comparative analysis of LCA results across UAV applications reveals that while electric UAVs reduce operational emissions, their life cycle impact is largely dictated by material selection and end-of-life disposal strategies. Carbon fiber production, for instance, is a major contributor to global warming potential (GWP), abiotic resource depletion, and human toxicity. Additionally, Li-ion battery manufacturing and disposal significantly impact terrestrial and aquatic ecotoxicity due to heavy metal contamination.

Table 8. UAV application and associated primary material concerns.

Uav Application	Primary Material Concerns	Environmental Hotspots in LCA	Potential Sustainable Alternatives
Delivery Drones (logistics)	CFRP, Li-ion Batteries	High embodied energy in battery production, e-waste concerns	Solid-state batteries, recycled CFRP
Surveillance Drones	CFRP, Aluminum, Titanium	Energy-intensive metal refining, limited CFRP recyclability	Bio-composites, lightweight alloys
Agricultural Drones	CFRP, GFRP, Bio-composites	Chemical degradation, high maintenance	UV-resistant bio-composites
Military UAVs	Aramid composites, Radar-absorbing coatings	High toxicity, non-recyclable materials	Recyclable thermoplastic composites

shows UAV application and associated primary material concerns.

To reduce the environmental impact of UAVs across applications, research should focus on:

• Exploring thermoplastic composites and recycled carbon fiber can mitigate the high energy demand associated with virgin CFRP manufacturing.
• Moving toward solid-state batteries, sodium-ion batteries, or structural energy-storing composites can help reduce dependence on lithium, cobalt, and nickel.
• For applications such as agriculture and low-altitude surveillance, natural fiber composites and biodegradable resins offer an eco-friendly alternative to traditional petroleum-based polymers.

The adoption of bio-based composites and recycled carbon fibers in UAV design presents a promising approach to mitigating the environmental impact of drone manufacturing without compromising structural performance. Bio-based composites, typically derived from natural fibers such as flax, hemp, and jute, offer a lower carbon footprint and higher energy efficiency during production compared to synthetic alternatives. Their intrinsic damping properties, lower density, and tailorable mechanical performance make them viable for non-load-bearing UAV components, such as fuselage panels and aerodynamic fairings. However, their lower tensile strength and moisture sensitivity require hybridization with high-performance thermosetting or thermoplastic resins, such as bio-epoxy or polylactic acid (PLA), to achieve structural reliability. On the other hand, recycled carbon fibers (rCFs) obtained via pyrolysis or solvolysis techniques offer nearly 70–90% of the mechanical performance of virgin CFRP, while reducing energy consumption in fiber production by up to 75%. Discussion of recycled carbon fiber implies a drop-in replacement, but virgin fiber is aligned and continuous (UD FODF = 1, FVF = 0.7), while recycled fiber is short and random (FODF = 0.375, FVF = 0.2), so there is only 11% realization of mechanical properties in the latter composite. These materials can be reintegrated into UAV structures using thermoplastic-based matrices, enabling reusability and improved lifecycle sustainability. Moreover, hybrid laminates combining bio-based fibers and rCFs can optimize stiffness-to-weight ratios, making them suitable for UAV frames and wings while maintaining recyclability advantages. Despite challenges in fiber–matrix adhesion and variability in recycled fiber properties, ongoing advancements in surface treatments and resin infusion techniques are improving their mechanical reliability. Thus, integrating bio-based composites and rCFs in UAV structures represents a strategic shift toward energy-efficient, low-waste manufacturing, aligning with lightweight performance demands while minimizing material obsolescence.

The comparative LCA of UAVs across applications underscores the significant role material selection plays in shaping the environmental footprint of drones. While battery technology advancements can reduce operational emissions, material sustainability, and end-of-life recyclability remain crucial factors in achieving long-term environmental benefits. Future UAV development should prioritize lightweight, durable, and recyclable materials to optimize both performance and sustainability across various drone applications.

9. Conclusions

The increasing adoption of UAVs across diverse industries necessitates a careful balance between structural performance and environmental sustainability. This review has systematically evaluated materials used in UAV construction, highlighting the trade-offs between mechanical efficiency, durability, and ecological impact. Traditional materials such as aluminum and titanium have been widely used due to their high strength and durability, but composite materials, particularly carbon fiber-reinforced polymers (CFRP), Kevlar^®, and glass fiber composites, have emerged as superior alternatives due to their high stiffness-to-weight ratio and aerodynamic efficiency.

However, CFRP and other high-performance composites present significant environmental challenges due to their energy-intensive manufacturing and limited recyclability. This study underscores the role of life cycle assessment (LCA) in quantifying these environmental burdens and guiding the transition toward sustainable UAV material selection. The findings reveal that while lightweight composites enhance flight efficiency and operational endurance, their high embodied energy and carbon footprint necessitate innovative solutions such as recycled carbon fiber (rCF), hybrid laminates, and bio-based composites.

Through comparative analysis of UAV materials, the study highlights the potential of hybrid and recycled materials in mitigating environmental impacts while maintaining structural integrity. The integration of thermoplastic-based matrices, along with advancements in composite recycling technologies, offers a promising pathway toward circular economy principles in UAV manufacturing. Additionally, multi-criteria decision-making (MCDM) approaches and Monte Carlo simulations have demonstrated the importance of balancing sustainability with mechanical performance, reinforcing the need for future research in optimizing UAV materials.

Looking ahead, further studies should focus on full life-cycle UAV sustainability assessments, including improved end-of-life strategies, second-life applications, and advancements in energy-efficient UAV production. The use of alternative energy sources, modular UAV designs, and bio-based composite technologies could play a critical role in enhancing UAV sustainability while maintaining high-performance standards. By bridging the gap between engineering efficiency and ecological responsibility, this study provides a foundation for the next generation of energy-efficient, low-impact UAV materials, supporting the transition toward a more sustainable aerospace industry.