Redesign of a Cargo-Bay Honeycomb Sandwich Panel for RF Compatibility

Sandwich composite panels, consisting of high-stiffness facesheets bonded to a lightweight core, offer high strength and stiffness-to-weight ratios, making them well-suited for aerospace applications. Embedding Radio Frequency (RF) payloads in these structures, however, requires cutouts and fasteners that interrupt core load paths and can degrade both mechanical integrity and RF performance. This paper details the redesign of an aluminum honeycomb cargo-bay panel on a twin-engine uncrewed aerial system (UAS) to meet simultaneous structural, modal, electromagnetic, and environmental requirements for operations in polar environments. The baseline panel featured aluminum facesheets, core terminations that did not share load with the closeouts, and exposed honeycomb at apertures that produce local stress concentrations and leave the core vulnerable to moisture ingress, icing, and corrosion. The redesigned panel replaces the metallic facesheets with S2-glass/epoxy facesheets bonded to a 1 in. HRH-10 Nomex® core and introduces removable S2-glass/epoxy-Rohacell® sandwich aperture covers, bonded composite-metal closeouts, and sealed core compartments. A 1D RF boundary-value (BVP) model and finite element analysis show that the new configuration keeps reflected power below roughly 5% across the 2–8 GHz band at normal incidence and maintains positive margins of safety with a ∼7% reduction in panel weight relative to the legacy panel. The redesigned panel provides an RF-compatible, structurally adequate replacement for the cargo-bay panel and serves as a practical example for similar RF-transparent structural panels on future platforms.