172,610 research outputs found
Capital flight and war
No full textThe author provides empirical evidence on the effects of inflation on post-war capital flight flows. He tests the hypothesis that inflation has a positive additional impact on capital flight flows after war. He uses a new panel dataset of 77 developing countries, of which 35 experienced at least one episode of war between 1971 and 2000. The author uses a range of estimation methods and four capital flight measures-Cline, World Bank Residual, Morgan Guarantee, and Dooley. The results consistently support the research hypothesis: Post-war inflation increases annual capital flight flows by about 0.005 to 0.01 percentage points of GDP. This effect is substantial in total at high inflation rates. The implication is that low inflation helps to curb capital flight in post-conflict economies.Economic Theory&Research,Banks&Banking Reform,Investment and Investment Climate,Settlement of Investment Disputes,Achieving Shared Growth
The HIRM+ Flight Dynamics Model
No full textThe major objective of the GARTEUR Action Group on Analysis Techniques for Clearance of Flight Control Laws FM(AG-11) is the improvement of the flight clearance process by increased automation of the tools used for modelbased
analysis of the aircraft’s dynamical behaviour. What is finally needed are techniques for faster detection of the worst case combination of parameter values and manoeuvre cases, from which the flight clearance restrictions are be derived. The basis for such an analysis are accurate mathematical models of the controlled aircraft. In this chapter the HIRM+ flight dynamics model is described as one of the benchmark military aircraft models used within FM(AG-11). HIRM+ originates from the HIRM (High Incidence Research Model) developed within the GARTEUR Action Group on Robust Flight Control M(AG-08). In building the HIRM+, additional emphasis has been put on realistic modelling of parametric uncertainties
Flight test: Supporting the investigation of factors affecting loss of control of light aircraft
No full textA quarter of all fatal General Aviation accidents in the UK during the period 1980 to 2006 involved Loss of Control (LoC) in Visual Meteorological Conditions (VMC). LoC has consistently appeared in accident statistics over this period, but at apparently different rates for different aircraft types. This raises two important questions - why do these LoC events happen and why is there a difference between aircraft types?.
One case in point is that of the Cessna 150 /152 and over the 27-year period
analysed, the Cessna 150 falls approximately on the average for fatal accidents in the UK GA fleet, whereas the Cessna 152 exhibits a lower accident rate. Brunel Flight Safety Laboratory, in conjunction with the UK
General Aviation Safety Council, undertook to try and understand why this is
so. The key design differences in relation to performance and handling qualities were researched using available published material and informal interviews with type-experienced students, pilots and flying instructors.
A flight test programme was conducted using examples of both aircraft types to gather additional research data, to assess and compare the apparent performance and handling qualities (both qualitatively and quantitatively). Flight tests were performed at three different CG conditions relevant to the key design differences, concentrating upon apparent longitudinal (static and dynamic) stability and control characteristics, stall and low-speed handling
characteristics, and cockpit ergonomics / pilot workload. In all tests, normal
(unmodified) flying club aircraft were used, in most cases with a 2-man (TP+FTE) crew. Data was recorded manually on test cards and
automatically using a low-cost, commercially available, portable FDR.
Proven theory was used to estimate static margins and pilot stick forces and gradients in the region of the stall, the pre-cursor to an LoC event.General Aviation Safety Council (GASCo
Sounding Rockets as a Real Flight Platform for Aerothermodynamic CFD Validation of Hypersonic Experiments
No full textThis paper describes the possibilities of sounding rockets to provide a platform for flight experiments in hypersonic conditions as a supplement to wind tunnel tests. Real flight data from measurement durations longer than 30 seconds can be compared with predictions from CFD calculations. This paper will regard projects flown on sounding rockets, but mainly describe the current efforts at Mobile Rocket Base, DLR on the SHarp Edge Flight EXperiment SHEFEX
Optimizing Automatic Flight Condition Recognition through a Multi-Strategy Machine-Learning Based Approach
No full textFlight Condition Recognition (FCR) is essential in the usage monitoring of helicopters, as maneuver instances determine the usage spectrum, and thus the assessment of the original usage assumptions, adopted at design time for the definition of the retirement life of its components. Automated FCR capabilities, exploiting algorithms to detect the aircraft maneuvers by appropriate processing of on-board sensors measurements, allow us to reconstruct the usage spectrum, supporting the definition of improved maintenance manuals, with replacement times and inspection intervals tailored to the helicopters actual usage, thus enabling Condition-Based Maintenance (CBM) schemes. However, designing an efficient automatic FCR system is a challenging task, due to the complex machine dynamics characterizing the different flight regimes. In this work, we show how to optimize a machine-learning based approach to FCR design by exploiting a multi-strategy time-series segmentation framework, which combines two supervised learning approaches that leverage sliding windows and stacking ensembles to produce reliable estimates of the flown regimes. The approach is validated on an experimental dataset of nearly 500 labeled flights from two helicopter models, demonstrating its effectiveness in predicting the different maneuver types, and its improvement over a single-strategy approach
Propeller ground and ceiling effect in forward flight
No full textClick on the DOI link to access this article at the publishers website (may not be free).The study of the fixed-pitch small-scale propeller in ground/ceiling effect is extended to forward flight conditions. Force-based experiment and smoke flow visualization is conducted at the University of Dayton Low Speed Wind Tunnel. The propeller is mounted at different incidence angles to simulate the transition to forward flight from hover and forward flight conditions. The effect of propeller incidence angle seems to be negligible at J=0. The power required at constant thrust shows an increasing trend after a threshold advance ratio for each h/D and then decreases steeply upon further increase in advance ratio. Smoke flow visualization revealed the presence of three distinct zones separated by the onset of the fountain vortex and the onset of the ground vortex at each ground distance. At advance ratios below the onset of the fountain vortex lies the optimal ground effect zone. An increase in advance ratio beyond this threshold will result in power increment due to the fountain vortex. Further increase in advance ratio initiates the onset of the ground vortex where the ground effect is significantly reduced. The onset of the fountain vortex and the ground vortex occurs at lower advance ratios for a propeller at an incident angle to the ground. Copyright © 2022 by the Vertical Flight Society. All rights reservedThe author would like to thank Dr. Michael. V. OL for his advice throughout the study; Nevin Jestus and George Gogidze from the University of Dayton Low Speed Wind Tunnel Research lab for assisting the flow visualization experiment in the study; and the University of Dayton Innovation Center for funding the author’s attendance of VFS 78th Annual Forum
Loss of control testing of light aircraft and a cost effective approach to flight test
No full textCopyright @ The Society of Flight Test EngineersLoss of control in Visual Meteorological Conditions (VMC) is the most common cause of
fatal accidents involving light aircraft in the UK and probably worldwide. Understanding
why LoC events occur and why there are apparent differences between aircraft types is currently under investigation by Brunel Flight Safety Laboratory (BFSL). Using a case study approach for selected light aircraft used in the training environment
and based upon a 29 year study of UK fatal accidents, BFSL undertook a qualitative and
quantitative review of fatal stall/spin accidents using a combination of statistical and qualitative analysis. Aircraft/model design differences and published material were reviewed with respect to performance and handling qualities for possible clues, and informal interviews were conducted with type-experienced students, pilots and flying
instructors. A flight test programme was executed using multiple examples (for fleet-wide attributes) of aircraft models to enable assessment and comparison of flying qualities (both qualitatively and quantitatively). Working within the continuous budget constraints of academia, a creative and cost effective flight test programme was developed without compromising safety. The two-man team (TP & FTE) used standard (unmodified) flying club and syndicate aircraft in conjunction with non-invasive low cost flight test instrumentation. Tests included apparent longitudinal (static and dynamic) stability and control characteristics, stall and low-speed handling characteristics and cockpit
ergonomics / pilot workload. During this programme, adaptations were also made to the
classic Cooper-Harper “point tracking” method towards a “boundary avoidance” method.
The paper describes tools and techniques used, research findings, the team's lessons
learned and proposed future research. It also discusses the possible application of
research results in aircraft, pilot and environmental causal factors, enabling a better understanding of LoC incidents and future avoidance within the light aircraft community.Financial support from the Thomas Gerald Gray Charitable Trust Research Scholarship Scheme was used in this study
Development of heuristic procedures for flight rescheduling in the aftermath of irregular airline operations
No full textIncludes bibliographical references (p. [151]-158)Airlines are constantly faced with operational problems which develop from severe weather patterns and unexpected aircraft or personnel failures. However, very little research has been done on the problem of addressing the impact of irregular operations, and developing potential decision systems which could aid in aircraft re-scheduling. The primary goal of this research project has been to develop and validate algorithms, procedures and new methodologies to be used to reschedule planned activities (flights) in the event of irregular operations in large scale scheduled transportation systems, such as airline networks. A mathematical formulation of the Airline Schedule Recovery Problem is given, along with a decision framework which is used to develop efficient solution methodologies. These heuristic procedures and algorithms have been developed for potential use in a comprehensive real-time decision support systems (DSS), incorporating several aspects of the tactical operations of the transport system. These include yield management, vehicle routing, maintenance scheduling, and crew scheduling. The heuristic procedures developed will enable the carrier to recover from an irregular operation and maintain an efficient schedule for the remainder of a given resolution horizon. The algorithms are validated using real-world operational data from a major US domestic carrier, and data from an international carrier based in the Asia Pacific region. A comprehensive case study was conducted on historical operational data to compare the output of the algorithms to what actually occurred at the airline operation control center in the aftermath of an irregularity. Some of the issues considered include the percentage of flights delayed, percentage of flights cancelled, and the overall loss in operating revenue. From these analyses, it was possible to assess the potential benefits of such algorithms on the operations of an airline
Data supporting: Comparing Drosophila suzukii flight behavior using free-flight and tethered flight assays
No full textThe data set contains flight behaviors of lab-reared summer and winter morphs Drosophila suzukii on a tethered flight mill and in a free flight chamber. For tethered flight mill we recorded propensity (flight or no flight), velocity, density, and duration of flight. For the free flight chamber we recorded propensity, phototaxis (flight towards sunlight cue), bouts (the number of take-offs), and duration of flight.Winter and summer morph Drosophila suzukii flight behavior on a tethered flight mill and free flight chamber was documented. The purpose of this data were to document the limitations, benefits, and effects the two methods could have on assessing an insect’s flight capacity.Minnesota Invasive Terrestrial Plants and Pests Center (through the the Environment and Natural Resources Trust Fund; mitppc.umn.edu)Kees, Aubree M; Tran, Anh K; Hutchison, William D; Aukema, Brian H; Rao, Sujaya; Rogers, Mary A; Asplen, Mark A. (2022). Data supporting: Comparing Drosophila suzukii flight behavior using free-flight and tethered flight assays. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/4nsz-x660
Flight Capital and its Reversal for Development Financing
No full textcapital flight, flight capital reversal, development finance
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