Flight Test and Aircraft Certification

Flight Test Tracking and Envelope Expansions Built In

When it comes to satisfying all the test points requested from any Certifying Body, a lot of test cases are required to prove the aircraft as well as covering all the envelope corner points and possible failures.  This requires a significant number of tests to cover different phases of flight and aircraft configurations.  To build up the flight test cases, a structured Envelope Expansion programme is needed using model uncertainty analysis to identify the limiting tests whilst progressively reducing the uncertainty and expanding the test points. The j2 Universal Tool-Kit provides a rapid modelling environment and automatic flight matching capability to speed up the process.  At the same time, developing a validated high fidelity digital twin means that more read across from predictive analysis and demonstrated tests can be accepted.

The first stage when looking at flight test for a new or modified aircraft design is the process of envelope expansion.  This ensures that at every stage, the test can be performed safely and data can be collected and fed back into the test program for further testing.  To achieve this there is a need to build an initial A Priori baseline model to examine the different levels of uncertainty across different parameters and to evaluate how those impact the aircraft, enabling the limiting tests and test points to be found.

The j2 Universal Tool-Kit provides the ability to build an initial A Priori model within j2 Builder or to use an existing model from external code, integrated through the j2 Developer API.  j2 Builder provides the ability to create Delta models that reference back to the original baseline and can add the different uncertainty values across multiple parameters.  Using j2 Freedom, the set of flight tests can be evaluated across the envelope using all delta models.  The results of the dynamic analysis can be cross checked against limitations and excursions with autogenerated boundaries built into j2 Visualize.  Using templates and the unique charting capabilities of j2 Visualize this process can identify the limiting tests.  These can be evaluated with a Pilot-in-the-loop in real-time using j2 Pilot, allowing the models to be flown on any simulator platform without any data transfer.

Following the test, the data can then be loaded back into j2 Flight and the results compared against the original predictive model through Re-Prediction.  The automatic tuning capability means that the baseline A Priori model can be updated and all the delta models connected to it are then using the corrected values.  Where corrections have taken place, the level of uncertainty can then be reduced and the next set of tests evaluated.

With the data driven Universal Tool-Kit coupled with the automatic data processing capabilities, the envelope expansion effort can be reduced by almost 40%.

With a validated model developed the complete flight envelope can be tested.  This helps to establish the key corner points that need to be demonstrated and allows read across of other test points reducing further the burden of test flights necessary.  This can lead to a faster certification process with reduced flying hours.