Articles written in Sadhana

    • Limitations of Flight Path Reconstruction techniques


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      The Flight Path Reconstruction (FPR) techniques are performed to verify the data compatibility check and post-flight. This is often achieved by calibrating the onboard sensors such as inertial and airdata sensors. In this paper, the limitations of FPR techniques in terms of Maximum Likelihood Estimation (MLE) andExtended Kalman Filter (EKF) and Unscented Kalman Filter (UKF) have been reported. To demonstrate the FPR and sensor calibration, kinematic trajectory simulations with wind box type maneuvers have been performed. It is also shown as how a kinematic simulation is valid for the studies carried out in this work.

    • A novel methodology to update table in air data system of a high performance fighter aircraft


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      Accurate air data parameters and measurements are critical for the successful flight missions of any modern fighters. Externally mounted vanes and probes measure the local flow angles, pressure, and temperature. These local measurements are to be corrected through a calibration process to obtain the free stream flow angles, pressure, and ambient temperature, etc. The preflight calibration of these sensors are carried out using wind tunnel tests/CFD computations. This paper presents a novel methodology to update air data table of these sensors, post-flight. The Air Data Computer (ADC) of the aircraft discussed in this paper hosts air data tables that are pre-calibrated using the Maximum Likelihood Estimation (MLE) method. However, challenges have been experienced in extending MLE methods for unsteady flights, when dynamic effects prevail. Unsteady conditions during wind up turns are inevitable to perform calibration at High Angles of Attack (AoA) regimes. Hence, an extended Kalman filter based methodology is proposed for calibration and table update. A complete process is tested for an entire flight envelope having 200 and odd flights. The results demonstrate the strength of the technique for air data calibration and table update in ADC.

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