The integration of LEO satellites with GNSS/INS into a robust LeGNSS positioning subsystem for Unmanned Aerial Vehicles (UAVs) addresses the limitations of traditional GNSS and INS systems. The proposed LeGNSS integrates low-earth orbit (LEO) satellite data with GNSS and MEMS-based inertial systems to enhance UAV positioning accuracy, reliability, and fault tolerance. It aims to overcome challenges like signal degradation and sensor errors through advanced correction and optimal filtering techniques. The paper utilizes Matlab simulations to analyse UAV positioning, considering dynamic environmental factors like wind. It emphasizes the integration of GNSS and INS systems to improve position estimation, highlighting the need for sophisticated filtering and error management. The study demonstrates improved positioning accuracy with the LeGNSS subsystem compared to traditional methods and suggests its application in various sectors employing unmanned aircraft. The research enhances UAV positioning technology and improves safety and operational efficiency.