A Systems Engineering Framework for Acoustic and Visual Signature Management in Small UAVs for Maritime Monitoring and ISR-Oriented Research Applications

Small unmanned aerial vehicles (UAVs) are increasingly used in maritime monitoring, coastal inspection, environmental assessment and ISR-oriented research applications. Their operational and scientific value depends not only on endurance, payload capacity and navigation performance, but also on the extent to which acoustic and visual signatures can be measured, compared and managed without compromising aerodynamic efficiency, energy consumption or system reliability. This paper develops a systems engineering framework for acoustic and visual signature management in small multirotor UAVs, derived from a graduate thesis project on UAV modification for maritime-support applications. The proposed framework integrates measurable requirements, acoustic metrics, visual observability indicators, design-variable traceability and staged verification logic. Acoustic assessment is organized around sound pressure level, overall sound pressure level, blade-passing frequency and harmonic content, while visual assessment is structured through luminance contrast, apparent angular size, surface reflectance and background-dependent observability. Rather than presenting operational stealth claims, the study provides a conservative and verifiable methodology for transforming conceptual UAV modification work into reproducible scientific evidence. The contribution of this work is a publication-oriented framework that connects aeroacoustics, CFD-supported modelling, visual observability and multi-domain trade-off analysis within a responsible dual-use research boundary. The framework supports the systematic evaluation of UAV signature-management strategies while preserving academic transparency, technical reproducibility and ethical publication standards.