Different techniques which might be used to cool hypersonic aircraft structures are reviewed. A numerical model for simulating the performance of nosecap or wing leading edge heat pipes is presented, and the relations related to the capillary and boiling limitations are derived. The numerical results show that the wick design in the nose and leading edge regions is crucial to the capillary limit consideration. The numerical model presented in this paper provides an efficient method to analyze the transient and steady-state performances of the nosecap, and wing leading edge heat pipes for the heat pipe design.