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 in addition to 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 to be flown and data collected. The j2 Universal Tool-Kit provides a rapid modelling environment and an automated flight data matching capability to speed up this process. At the same time, developing a validated high fidelity digital twin means it is possible to use more 'read across' data from predictive analysis and other demonstrated tests in the data acceptance process.
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 evaluation. 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 any 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 be used to add different uncertainty values across multiple parameters, all without corrupting the baseline model version. Using j2 Freedom, flight tests can be evaluated across the envelope off line before any flight testing using the delta model capability. The results of the dynamic analysis can be cross checked against limitations and excursions with autogenerated boundaries and report templates built in j2 Visualize. Using the templates and the unique charting capabilities of j2 Visualize this process can identify any limiting tests. These can be evaluated with a Pilot-in-the-loop evaluation in real-time using j2 Pilot, allowing the j2 models to be flown on any simulator platform without any coding or data import/export tasks and be fully evaluated before committing to any flight tests. This is a unique capability that can risk assess each and every flight test requirement before the aircraft has left the ground.
Following the flight test, the collected data can then be loaded back into j2 Flight and the results compared against the original predictive model using Re-Prediction. The automatic model tuning capability means that the baseline A Priori model can be updated and all the delta models connected to it updated using the corrected values. Where corrections have taken place, the level of uncertainty can then be reduced and the next set of flight tests evaluated.
With the data driven j2 Universal Tool-Kit coupled with the automatic data processing capabilities, the efforts normally required to complete the envelope expansion task can be reduced by almost 40%.
With a validated model developed, the complete flight envelope can be evaluated and analysed. This helps to establish the key corner points that need to be demonstrated and also allows ‘read across’ of other test points reducing further the burden of flight testing necessary. This can lead to a faster certification process with up to 15% fewer flying hours.
Being able to run and analyse each and every proposed flight test off line is a big step forward in flight safety risk assessment practices and provides a quick and easy evaluation, analysis and simulation process in advance of any proposed test flying of an aircraft.