## 2 UAV Platform Evolution
### UAV Platforms Based on Aerodynamic Features
**Fixed-wing** UAVs offer streamlined airframe designs that generate a lift via forward airspeed, such as a conventional airplane. Their aerodynamic efficiency, combined with non-rotating propulsion, enables substantially longer flight times and distances than multirotor drones, making them suitable for wide-area mapping [57]. However, fixed-wing UAVs cannot take off vertically, land, or hover, relying on catapults, hand launches, skids, or bellies for landing. This limits their utility for inspecting and scanning localized urban structures where hovering proximity is critical. The maneuvering flexibility is also reduced compared to multirotor UAVs. Yet, for extensive bird's-eye urban imaging, fixed-wing UAVs play an important role. **Hybrid VTOL** platforms aim to deliver the best attributes of multirotor takeoff and landing capabilities combined with the cruising range and speed of fixed wings. This is achieved by lifting off vertically using the rotor thrust before transitioning the rotors to forward flight propulsion once an adequate altitude is achieved [61]. Some advanced hybrids can even optimize the transition speed and angle based on factors, such as wind conditions, using onboard AI [62]. This blend of VTOL flexibility and improved flight efficiency makes hybrid drones well-suited to diverse climate sensing roles, from a localized infrastructure inspection to wide-area thermographic mapping. However, their mechanical complexity remains a reliability challenge compared to other UAV platforms, as shown in Figure 3.  
Across UAV types, flight times reaching 30-60 minutes are commonplace at present, enabled by the developments in battery technology. Lithium polymer and lithium-ion packs can deliver the electrical storage versus weight ratio needed for sustained UAV operations. UAV airframes have also become more durable, yet lightweight, by utilizing carbon-fiber composites and engineered thermoplastics, such as PLA (polylactic acid) [39]. Enhanced satellite navigation integration provides robust autonomous control and stability. These airframes, avionic, and battery innovations underpin drones' expanding capabilities for flexible and responsive climate research flights, even in turbulence-prone urban settings. Furthermore, UAVs offer highly customizable and scalable platforms for integrating specialized sensor payloads needed for diverse climate data collection roles. Visible-spectrum cameras support creating detailed 2D and 3D maps of urban morphologies, vegetations,  
Figure 3: UAV classifications based on their aerodynamic features, level of autonomy, sensors, and power sources. Based on [60; 63; 64; 65]. and infrastructures [4]. Thermal infrared imaging enables microclimate variability, heat island mapping, and building insulation assessments [8]. Miniaturized gas sensors measure pollutants, such as carbon dioxide and particulate matter [66]. LiDAR scanners generate precise 3D point clouds of buildings and terrain [67]. Swapping these sensors between missions adapts UAVs to differing data capture needs. Onboard processing and AI further empower sensor integration and real-time analytics during flights.