Abstract: Hypersonic multi-body vehicles encounter highly transient and strongly interfering flows during stage separation, leading to pronounced nonlinear control-surface effectiveness and inducing a tightly coupled aerodynamic-kineMatic-control problem. At present, no ground-based facility exists that can reproducibly investigate controlled stage separation. This study develops and experimentally validates a controllable stage-separation testing technique that integrates “continuous-grid force measurement, high-fidelity interference-rudder modelling and real-time surface deflection”. First, a 2 mm-step continuous-grid force-measurement mode is employed to establish a high-density interference-rudder effectiveness database; an area-weighted two-dimensional interpolation scheme is then adopted to reconstruct the rudder effectiveness with high accuracy. Second, a compact, high-load actuator integrated into the model is designed to drive genuine surface deflections, and a coordination algorithm synchronising dynamic rudder motion with dual continuous-CTS traverse is developed. These elements constitute a controlled-separation test platform operable in either database-driven or real-deflection mode. BenchMark TSTO configuration tests are conducted to systematically assess the influence of rudder-modelling fidelity, deflection-simulation strategy and control-law implementation on separation trajectory. For the first time, closed-loop, controlled stage separation of a multi-body vehicle is reproduced in a hypersonic wind tunnel, significantly extending the ground-test portfolio for hypersonic multi-body separation.