This study investigates the influence of grid-fin chord Reynolds number \({\text{Re}}_{c}\) on the incremental static aerodynamic characteristics of a generic missile configuration with grid fins in the transonic regime. Wind tunnel tests were performed on a body-alone configuration and two grid-fin configurations with different blockage ratios over Mach numbers 0.6–1.2 and Rec ≈ 0.5 × 106–5.0 × 106, and incremental coefficients were obtained by subtracting body-alone data. The incremental axial force coefficient at zero angle of attack, \(\Delta {C}_{A0}\) , exhibits only weak dependence on \({\text{Re}}_{c}\) , while the incremental normal-force and pitching-moment slopes, \(\Delta {C}_{N\alpha }\) and \(\Delta {C}_{m\alpha }\) , and the center-of-pressure location \({X}_{\text{c}\text{p}}\) show strong Reynolds number sensitivity in the subsonic–transonic range, with increased \({\text{Re}}_{c}\) enhancing the stabilizing contribution of the grid fins and shifting \({X}_{\text{c}\text{p}}\) aft. These effects are stronger for the higher-blockage configuration, highlighting that transonic grid-fin performance is controlled by the combined influence of Mach number, lattice geometry, and chord Reynolds number.
