S.S.T. flight-profile optimisation

The development of a practical method for the calculation of optimal flight profiles for the supersonic transport Concorde is described. Existing optimisation techniques are modified to reduce the long computation times usually required for this type of problem. A modified `stopping-condition¿ approach is introduced to deal with the free terminal time problem. Switching times are used as control parameters to govern the use of reheat thrust on the aircraft, resulting in discontinuities in the state equations. The effect of these switching times on the optimality conditions is shown. The conjugate-gradient technique, with some modifications, is used in the solution of the problem. The definition of the inner product of the gradients is altered to accommodate the combined use of control variables and control parameters. Also, an alternative method to the restart approach for reducing the effect of error accumulation in the search directions is introduced. Finally, the effect of gradient scaling on the convergence of the problem is demonstrated. The optimisation of a representative flight for Concorde is presented to demonstrate the effectiveness of the method.