Shunted piezoelectric patches form an effective control mechanism for reducing vibrations of a mechanical system. One type of shunt, a negative capacitance circuit, is capable of suppressing vibration amplitude over a broad frequency range. Most previous work has focused on control of simple test structures such as beams and plates. This work studies the performance of the negative capacitance shunt connected to piezoelectric patches attached to a stiffened aircraft panel. The placement of the piezoelectric transducers is determined using a simplified finite element model of one bay of the panel. The numerical predictions are compared to experimental results for spatial average vibration for a point force input. The amount of control for increasing number of patches is also investigated. These results give a more accurate representation of the achievable performance in real world application.