Inverse flight simulation using aircraft performance models

The Systems Analysis Laboratory of Helsinki University of Technology (TKK) has developed an aircraft trajectory optimization routine based on an enhanced three degree-of-freedom (3-DOF) point mass flight simulation model. However, in simulating rapid maneuvers, 5-DOF performance modeling with proper dynamic behavior is required to achieve comparable realism with high-fidelity 6-DOF flight simulations. To be able to assess the realism of the computed optimal trajectories, an inverse simulation was developed on the basis of a 5-DOF flight simulation program Flyacm developed by the Laboratory of Aerodynamics at TKK. An integration-based inverse simulation algorithm was coded in Fortran and it runs the modified 5-DOF simulation as an iteration loop. The inverse simulation routine was applied to evaluate calculated optimal trajectories. The results led to improvements in the 3-DOF trajectory modeling and also gave new ideas on the inverse simulation algorithm. The capabilities of the inverse simulation algorithm are demonstrated using large-amplitude maneuvers.