Enhancing Real Time Monitoring Support for Safe Envelope Expansion

The paper describes a few simulation techniques implemented to support flight testing activities and safe envelope expansion of a high performance fighter aircraft. One of the important tasks of flight testing is to safely carry out parameter identification flight tests at the edge of the flight envelope (maximum angle-of-attack). Wind tunnel data updated on the basis of these flight tests is used to upgrade the aircraft flight control design. Flying for the first time close to envelope boundaries always presents an extra degree of uncertainty due to the nonlinear flight dynamics. This uncertainty needs to be removed by gradually expanding flight envelope through flight tests. Parameter Excursion Boundaries (PEBs) offer a convenient option to monitor the critical safety parameters in real-time during envelope expansion. PEBs decide the safe limits of excursion of these parameters for a specified flight condition and configuration. In the present case, batch simulation process of the relevant maneuvers to be carried out during the flight tests was used to generate the PEBs. Apart from this, online parameter estimation tool was also developed for improving the flight test efficiency and for assuring pilot and vehicle safety.