Optimizing Aircraft Performance With Adaptive, Integrated Flight/Propulsion Control

An adaptive, integrated flight/propulsion control algorithm called Performance Seeking Control (PSC) has been developed to optimize total aircraft performance during steady-state engine operation. The multimode algorithm will minimize fuel consumption at cruise conditions; maximize excess thrust (thrust minus drag) during aircraft accelerations, climbs, and dashes; and extend engine life by reducing Fan Turbine Inlet Temperature (FTIT) when the extended life mode is engaged. On-board models of the inlet, engine, and nozzle are optimized to compute a set of control trims, which are then applied as increments to the nominal engine and inlet control schedules. The on-board engine model is continually updated to match the operating characteristics of the actual engine cycle through the use of a Kalman filter, which accounts for anomalous engine operation. The PSC algorithm will be flight demonstrated on an F-15 test aircraft under the direction of the NASA Ames/Dryden Flight Research Facility. This paper discusses the PSC design strategy, describes the control algorithm, and presents results from high-fidelity, nonlinear aircraft/engine simulations. Simulation results indicate that thrust increases as high as 15 percent and specific fuel consumption reductions up to 3 percent are realizable by the PSC system.