Recently, the second law of thermodynamics has been used to develop the concept of a “common currency” for use in analysis and optimization of multidisciplinary systems. The second law approach relates the irreversibility (or entropy generation) in different subsystems or physical mechanisms to the overall system performance. Since entropy generation has the same units in every subsystem, this provides a common framework for evaluating the impact of each subsystem on the overall system performance. One difficulty in applying second law techniques to aerospace vehicles is the fact that commonly used engineering codes often do not simulate the physics necessary to directly calculate the irreversible entropy generation. An example is hypersonic aerodynamic codes based on local surface inclination (panel methods). In this paper, an enhancement to a low-fidelity hypersonic aerodynamic analysis code is developed, allowing calculation of irreversible entropy generation due to different aerodynamic mechanisms. This development is presented in context of a multidisciplinary framework for aerospace vehicle design.