<p>A novel method is presented to analyze the impact of hovering-based inter Unmanned Aerial Vehicle (UAV) based Free Space Optical (FSO) system on the performance and secure communication of serial relaying. This study improves upon previous research by comprehensively considering the effects of orientations, positions, and angle of arrival (AoA) fluctuations for end-to-end bit error rate (BER) analysis in serial relaying for disaster management applications. We examined the end-to-end performance by considering hovering state positions, orientations, AoA fluctuations, path loss, pointing loss, and the effects of turbulence. The influences of atmospheric turbulence, hovering state variations, and pointing errors are mitigated through the implementation of serial-relaying and Differential Chaos Shift Keying (DCSK) Modulation techniques. This approach enhances the overall transmission distance of inter-UAV-based FSO systems by addressing atmospheric turbulence, spreading factor and hovering state fluctuations. We derived an analytical expression for the end-to-end BER in serial relays incorporating DCSK modulation. The analytical results were plotted and compared with simulation results. This study provides insights into the design of inter-UAV-based FSO systems, evaluates serial relay performance under varying turbulence conditions, determines the required number of relays under specific turbulence scenarios, and assesses the achievable transmission distances.</p>