Aerospace Plane Ascending Trajectories with Heat Consideration

Abstract

This is a study of performance and control for transatmospheric (TAV) aerospace planes, that use air-breathing propulsion. The study is structured in two parts and considers the heat load near the stagnation point. The first part is analytical and consists of two cases, it seeks closed form solutions for the non-linear feedback controls (aerodynamic and thrust), which are necessary to transfer the (TAV) from one specified state to another specified state, while satisfying pairs of equality constraints (that is, Case I: constant acceleration with constant dynamic pressure and Case II: constant rate of climb with constant dynamic pressure). This leads to closed form solutions for the controls in feedback form and also for the heat rate and load. The analytical approach gives a reasonable approximation of the general ascent trajectory to orbit, where the two cases can be used in combination with different constant values of the constraints in different levels of the hypersonic trajectory. The analytical results were a useful guide in the numerical studies. The second part describes numerical simulation and optimization. The control laws, which minimize the heat load, are found in feedback form. A numerical example is worked out for illustration. The trajectory corridor and, in general, all the constraints are satisfied for heat load ≤ 350 kJ/cm2 using feasible controls.