Evaluation of Unmanned Aircraft Flying/Handling Qualities Using a Stitched Learjet Model

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Over the past 20 years, unmanned aircraft have taken over military missions that were deemed to be too “dull, dirty, or dangerous” for manned aircraft. The urgent demand for aircraft that can execute these missions has resulted in a “build-fly-fix-fly” development mentality. Currently, documents that specify flying and handling quality requirements for manned aircraft, such as MIL-STD-1797, list those requirements as “TBD” for unmanned aircraft. In an effort to develop metrics that can be used to quantify the handling qualities of unmanned aircraft and expand the database that can be used to develop handling quality requirements, an analysis was performed using a Simulink model of the Calspan LJ-25D Variable Stability System aircraft at the United States Test Pilot School. Two maneuvers were simulated: 1) a climbing spiral, and 2) a precision offset landing. These maneuvers were chosen to evaluate the maneuver performance and workload, as measured by control surface activity, while varying stability and control parameters. The data were used to identify trends between the stability and control parameters and the resulting workload and maneuver performance metrics. Thumbprint plots were generated to identify Level 1, Level 2, and Level 3 flying qualities and were compared to similar MIL-STD-1797 plots. Results point to using a combination of classical aircraft literal factors, such as the short-period damping and control anticipation parameter, with newly developed metrics, employing ℒ2 norm and Thiel’s inequality coefficient (TIC), to assess the maneuver performance and workload of the aircraft and flight controller during a maneuver.


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Source Publication

Journal of Guidance, Control, and Dynamics