This project involves the design and development of a long-endurance, fully autonomous fixed-wing Unmanned Aerial Vehicle (UAV) capable of collecting and transmitting environmental data over extended flight missions. The UAV will be built from the ground up, including a custom-designed flight controller, enabling full control over stabilization, navigation, and mission execution. The system is intended for environmental monitoring applications such as measuring atmospheric conditions, air quality, temperature, humidity, and other ecological parameters over large geographic areas. The aircraft will use a lightweight fixed-wing airframe optimized for aerodynamic efficiency and endurance, combined with an embedded avionics system that integrates sensors, communication modules, and autonomous control algorithms.