Flight Data Matching

Flight Test Data to High Fidelity Model Using J2 Universal Tool-Kit

The J2 Universal Tool-Kit provides a unique ability to handle all flight test data within a single Tool-Kit, removing noise and bias, smoothing data and being able to use the unique j2 automated data correction finding methodology. Run all your lateral flight test data cases in a single step and reduce the entire flight test data matching process by as much as 40%.

Flight Test data matching, the process which takes flight test data, analyses it and uses the outputs from this analysis to match the digital model too is a time consuming, slow and iterative process.  The skills required to successfully develop and tune a model using flight test data are learned over a long apprenticeship, often in excess of 25 years. Mostly, this is because aircraft are closely coupled systems so that changing one aspect on the model has a knock-on effect to multiple characteristics and responses. Finding the model fit which meets the requirements of the applicable standards e.g. FAA Part 60 rev 2 or equivalent when producing a high fidelity Level D type model for Pilot training fidelity is a difficult and very time consuming task.

j2 has already provided the information elsewhere in the website on how models can be developed using j2 Builder, j2 Elements, or external models or data integrated into j2 software using j2 Developer, elsewhere in the website, but now let us show you how j2 Flight is revolutionising the whole flight test data matching process.

There are many challenges that have to be overcome when developing a model using flight test data for simulator certification. Firstly, the regulatory requirements demands a more varied spread of flight test data for high fidelity simulation than for certification purposes.  This immediately presents challenges when purchasing OEM data packs.

In addition, poor quality flight data has many inconsistencies which if unchecked can introduce characteristics that are not part of the aircraft. When using existing tools, it is quote common for a range of frig factors to be used to correct the problems caused by such inconsistencies. Under examination such factors are easily identifiable.

An on going challenge has been the the length of time it takes to analyse the flight test data and manually identify the necessary corrections to the model, so that it matches the flight test data. This can have a significant and marked impact on the overall simulator build project cost.

Finally, the continued reduction in workforce/skillset with sufficient experience to continue to do things the “old way” is fast reducing and this presents a significant business risk for small, medium and even large simulator manufacturers as they look to protect that knowledge and move on from older legacy systems.

j2 has already vested significant time and energy in launching j2 Flight, its unique flight test data handling and analysis engine. j2 has already established an alternative methodology for  tuning models that does not require an OEM data pack.  j2 can also adjust existing models to refine new characteristics on and off line within a single continuous Tool-Kit and without any need to write code.

The j2 process and methodology can help with identifying what additional flight test data is required to develop full qualification test points for high fidelity simulation applications. This additional data can come from any source and can be used to tune the model as an alternative to OEM Data packs.

The j2 methodology is uniquely able to smooth flight test data and remove excessive noise/bias whilst leaving the real aircraft nuances untouched. J2 Flight includes a full Kalman Filtering capability that is used for Flight Path Reconstruction from the flight data.  In doing this, a kinematically consistent set of all 18 aircraft states are calculated.  These are smoothed and the bias removed so that they provide a clean set of test points for further analysis and QTGs. The j2 process also undertakes flightpath reconstruction, reprediction, parameter identification (PID) and it is able to identify model corrections for model tuning and QTG acceptance steps.

A further significant advance in methodology is that j2 software works at the coefficient level and as part of the analysis process, can uniquely place the model in the same point in space and time as the flight test aircraft. This removes the need for additional integration steps from the analysis as each analytical time step within j2 software is 1/1000th of a second. The benefit of this is that additional signal noise and a potential source of error from the analytical process is completely removed.

This well documented process is already fully commercial and provides a new approach that is robust, repeatable and teachable so that new engineers can be trained in how to tune models without the need of a 40-year apprenticeship. This breakthrough is already full supported and technically proven through j2 being awarded 2 x ITAR licenses with major US based simulator OEM’s.

The analysis that is possible within j2 software has also significantly reduced the work time needed to complete the flight test data matching process. The main reason for this improvement is that the j2 method does not require a test by test iterative process, instead  it can run all lateral and longitudinal tests in large batches, automating how corrections are found and this greatly speeds up the process. One client ran the entire flight test programme of lateral and longitudinal tests in a single analytical run, allowing the j2 software to automatically determine the necessary corrections needed to comply with the QTG tolerances to meet FAA part 60 requirements.