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Algorithms for resolving air traffic conflicts are tested on archived tracking data from 102 actual operational errors (violations of minimum required separation due to controller error). The algorithms compute horizontal or vertical resolution maneuvers for tactical conflicts in which the minimum required separation is predicted to be lost within approximately two min. The horizontal maneuvers are issued as heading vectors, and the vertical maneuvers are issued as standard altitude clearances. Algorithms for the vertical resolutions were presented in an earlier paper, and algorithms for the horizontal resolutions are described in this paper. Simulation results show that these resolution algorithms could have prevented most of the archived operational errors. In some cases, the controller failed to enter an altitude amendment consistent with the voice clearance, and in eight such cases the conflict was not detected early enough to be resolved in the simulation. The correct altitude amendments were added to the recorded data for those cases (to simulate the correct entry by the controller), and successful resolution was then achieved for all cases. [ABSTRACT FROM AUTHOR]

The research and development efforts outlined in this paper address the aerodynamic design of micro air vehicles that are capable of vertical takeoff and landing, as well as hovering. The effect of a propulsive slipstream on a wing's quasi-steady aerodynamics is investigated as an early step toward improving existing vertical takeoff and landing designs and control algorithms. Wind-tunnel testing was conducted on a propulsion system with contrarotating propellers, a wing, and the combined wing and propulsion system. Aerodynamic coefficient definitions are discussed with regard to vertical takeoff and landing micro air vehicles, and modified definitions are presented. [ABSTRACT FROM AUTHOR]

Two approaches are examined for finding the best stacking sequence of laminated composite wing structures with blending and manufacturing constraints: smeared-stiffness-based method and lamination-parameter-based method. In the first method, the material volume is the objective function at the global level, and the stack shuffling to satisfy blending and manufacturing constraints is performed at the local level. The other method introduced in this paper is to use lamination parameters and numbers of plies of the predefined angles (0, 90, 45, and -45 deg) as design variables with buckling, strain, and ply percentage constraints while minimizing the material volume in the top-level optimization run. Given lamination parameters from the top-level optimization as targets for the local level, an optimal stacking sequence is determined to satisfy the global blending requirements. On a benchmark problem of an 18-panel wing box, the results from these two approaches are compared to published results to demonstrate their potential. [ABSTRACT FROM AUTHOR]

This paper presents a fast tool that can be used during the preliminary design of isotropic and composite stiffened panels subjected to axial compression. It consists of two modules, one for the analysis and one for the optimization. The analysis is performed by implementing an analytical formulation to obtain the linearized buckling load and to study the nonlinear postbuckling field. In particular, closed-form solutions are derived for the linearized local and global buckling loads, and a semi-analytical procedure is implemented for the study of the nonlinear local postbuckling field. The optimization is based on genetic algorithms and allows taking into account buckling and postbuckling requirements with reduced computational time. Two examples regarding the minimum weight optimization of an isotropic panel and a composite panel are discussed and verified by means of finite element eigenvalue and nonlinear analyses. The total time required for the analysis and the optimization is of the order of a few minutes, and the difference between the analytical and numerical results is below 9% for the buckling load and below 3% for the postbuckling stiffness. [ABSTRACT FROM AUTHOR]

Autopilot systems are capable of reliably following flight plans under normal circumstances, but even the most advanced flight-management systems cannot provide robust response to most anomalous events including in-flight failures. This paper describes an emergency flight-management architecture that can be applied to piloted or autonomous aircraft, with focus on the design and implementation of an adaptive flight planner (AFP) that dynamically adjusts its model to compute feasible flight plans in response to events that degrade aircraft performance. A two-step landing-site selection/trajectory generation process defines safe emergency plans in real time for situations that require landing at an alternate airport. A constraint-based search algorithm selects and prioritizes feasible emergency landing sites, then the AFP synthesizes a segmented trajectory to the best site based on post-failure flight dynamics. The AFP architecture is general for any failure situation; however, operational success is guaranteed only with accurate post-failure performance characterization and a trajectory generation strategy that respects degraded flight envelope boundaries. A real-time segmented trajectory planning algorithm and case study results are presented for total loss of thrust failure scenarios. This emergency is surprisingly common and necessitates an immediate approach and landing without a go-around option. [ABSTRACT FROM AUTHOR]

The issue of monitoring aircraft performance during takeoff has been repeatedly considered in the last 50 years. This has been in response to concern over the low safety margins associated with this phase of flight and the lack of adequate objective performance-related information available to the crew during the takeoff maneuver. Two major difficulties, however, have to date inhibited the successful introduction of an instrument providing such information on the flight deck, namely, the provision of a reliable quantification of actual performance during the takeoff maneuver and the provision of an adequate display. This paper focuses on the former issue and evaluates the accuracy of a predictive performance monitoring algorithm developed at Cranfield University. The major hurdles that are associated with takeoff performance monitoring are briefly discussed, and the results of flight-based tests using data from large jet-transport operations presented. These results, which confirm a robustness that warrants the application of the algorithm in real-time performance monitoring, are also compared with those of an earlier flight test program using a twin turboprop aircraft. [ABSTRACT FROM AUTHOR]