(Georgia Institute of Technology, 2018-06)
Puranik, Tejas G.; Harrison, Evan D.; Mavris, Dimitri N.
A wide range of aircraft performance and safety analyses are greatly facilitated by the development and availability of reliable and accurate aircraft performance models. In an ideal scenario, the performance models would show inherently good agreement with the true performance of the aircraft. However, in reality, this is almost never the case, either owing to underlying simplifications or assumptions or due to the limited fidelity of available or applicable analysis tools. In such cases, model calibration is required in order to fine tune the behavior of available performance models to obtain the desired agreement with the truth model. In the case of point-mass steady-state performance models, challenges arise due to the fact that there is no obvious, unique metric or flight condition at which to assess the accuracy of the model predictions, and since a large number of model parameters may potentially influence model accuracy. This work presents a systematic two- level approach to aircraft performance model calibration that poses the calibration as an optimization problem using the information available. The first level consists of calibrating the performance model using manufacturer-developed performance manuals in a multi objective optimization framework. If data is available from flight testing, these models are further refined using the second level of the calibration framework. The performance models considered in this work consist of aerodynamic and propulsion models (performance curves) that are capable of predicting the non-dimensional lift, drag, thrust, and torque produced by an aircraft at any given point in time. The framework is demonstrated on two popular and representative single-engine naturally-aspirated General Aviation aircraft. The demonstrated approach results in an easily-repeatable process that can be used to calibrate models for a variety of retrospective safety analyses. An example of the safety analyses that can be conducted using such calibrated models is also presented.
(Georgia Institute of Technology, 2016-06)
Puranik, Tejas G.; Harrison, Evan D.; Min, Sanggyu; Jimenez, Hernando; Mavris, Dimitri N.
Ensuring a safe and stabilized approach and landing is one of the important objectives in General Aviation applications. This phase is one of the main phases during which accidents occur. A "nominal" or reference trajectory for General Aviation approach and landing operations is critical for flight instruction and retrospective safety assessments reliant on flight data records captured with on-board systems. While this is a more crisply defined area in commercial aircraft operations, it is not so well-defined in General Aviation. The different aspects that need to be considered in defining a nominal trajectory and provide analyses that can be carried out using flight data records are examined. Various ways of defining this nominal or reference approach trajectory are proposed with the eventual aim of using this in conjunction with energy-based methods and metrics to assess and enhance safety in General Aviation aircraft operations.
(Georgia Institute of Technology, 2016-06)
Puranik, Tejas G.; Harrison, Evan D.; Min, Sanggyu; Jimenez, Hernando; Mavris, Dimitri N.
Energy management and energy state awareness are important concepts in aircraft safety analysis. Many loss-of-control accidents can be attributed to poor energy management. Energy-based metrics provide a measurable quantity of the energy state of the aircraft and can be viewed as an objective currency to evaluate various safety-critical conditions. In this work, we have surveyed key energy-based metrics from various domains and identified the challenges of implementing these metrics for General Aviation operations. Modifications to existing metrics and definition of some new energy metrics are proposed. A methodology is developed that can be used to evaluate and visualize the energy metrics. These energy metrics can then be used to understand and enhance General Aviation aircraft safety using retrospective flight data analysis.