As part of NASA's Aviation Safety and Security Program, research has been in progress to develop aerodynamic modeling methods for simulations that accurately predict the flight dynamics characteristics of large transport airplanes in upset conditions. The motivation for this research stems from the recognition that simulation is a vital tool for addressing loss-of-control accidents, including applications to pilot training, accident reconstruction, and advanced control system analysis. The ultimate goal of this effort is to contribute to the reduction of the fatal accident rate due to loss-of-control. Research activities have involved accident analyses, wind tunnel testing, and piloted simulation. Results have shown that significant improvements in simulation fidelity for upset conditions, compared to current training simulations, can be achieved using state-of-the-art wind tunnel testing and aerodynamic modeling methods. This paper provides a summary of research completed to date and includes discussion on key technical results, lessons learned, and future research needs.

The radial wrinkle pattern generated by a liquid drop on a floating elastic sheet has stimulated a number of advances in the understanding of wrinkle patterns in ultrathin sheets. A puzzle associated with the spatial extent of this simple, highly symmetric pattern has only recently been resolved, but several other basic aspects of the pattern remain unexplained. Our previous experiments have studied the extent and wavenumber of the pattern via 2-dimensional images. In the current study we report a full 3-dimensional topographical characterization of this archetypical problem, and of its counterpart, a bubble beneath a sheet. In addition to measurements of the wrinkle amplitude, these studies reveal the elastic deformation and the resulting wrinkle pattern beneath the drop. We also show that the flat boundary condition at the contact line of the drop is achieved by a cascade of wrinkles on both sides of the boundary. Finally, we report studies by high-speed video imaging of the propagation of the wrinkle pattern, with the unexpected result that the wavenumber is established early in the development of the pattern, before it has reached its full spatial extent.

No abstract

The Constitutional Convention was established by the Irish government in 2012. It was tasked with making recommendations on a number of constitutional reform proposals. As a mini-public, its membership was a mix of 66 citizens (randomly selected) and 33 politicians (self-selected). Its recommendations were debated on the floor of the Irish parliament with three of them leading to constitutional referendums; other recommendations are in the process of being implemented. This article uses data gathered during and after the operation of the Convention to examine this real-world example of a mixed-membership mini-public. The focus is on how the inclusion of politicians may have impacted on the Convention’s mode of operation and/or its outcomes. We find little impact in terms of its operation (e.g. no evidence that politicians dominated the discussions). There is evidence of a slight liberal bias among the politician membership, but this had little effect on the outcomes.

Toward the goal of reducing the fatal accident rate of large transport airplanes due to loss of control, the NASA Aviation Safety Program has conducted research into flight control technologies that can provide resilient control of airplanes under adverse flight conditions, including damage and failure. As part of the safety program's Integrated Resilient Aircraft Control Project, the NASA Airborne Subscale Transport Aircraft Research system was designed to address the challenges associated with the safe and efficient subscale flight testing of research control laws under adverse flight conditions. This paper presents the results of a series of pilot evaluations of several flight control algorithms used during an offset-to-landing task conducted at altitude. The purpose of this investigation was to assess the ability of various flight control technologies to prevent loss of control as stability and control characteristics were degraded. During the course of 8 research flights, data were recorded while one task was repeatedly executed by a single evaluation pilot. Two generic failures, which degraded stability and control characteristics, were simulated inflight for each of the 9 different flight control laws that were tested. The flight control laws included three different adaptive control methodologies, several linear multivariable designs, a linear robust design, a linear stability augmentation system, and a direct open-loop control mode. Based on pilot Cooper-Harper Ratings obtained for this test, the adaptive flight control laws provided the greatest overall benefit for the stability and control degradation scenarios that were considered. Also, all controllers tested provided a significant improvement in handling qualities over the direct open-loop control mode.