This paper presents a numerical model intended for a system study of transpiration cooled thermal protection systems. The code PIRATE (Porous Impulse Response Analysis for Transpiration cooling Evaluation) enables rapid transient calculations for thermal protection systems of hypersonic flight vehicles. In the code, semi-empirical aerodynamic correlations are employed. However, the code could also be used by applying higher fidelity inputs from CFD calculations for more complicated vehicle geometries. The wall temperature distribution is calculated by utilising the thermal impulse and step responses of porous media, increasing the calculation speed significantly. A heat flux balance is considered for a one-dimensional porous material. The code is validated with experimental data of plasma wind tunnel tests and the SHEFEX II flight experiment. The transient heating of a flat plate model in a steady state flow condition in the L2K plasma wind tunnel is assessed for both un-cooled and transpiration cooled cases. The SHEFEX II flight simulation accounts for transient external flow conditions * Post-doctoral research assistant, Hypersonics group, Oxford Thermofluids Institute, AIAA Member.