302,152 research outputs found
Aerothermodynamics issues of the DLR hypersonic flight experiment SHEFEX-I
No full textHere is presented an overview of the hypersonic experiment on sharp edge concepts, SHEFEX-I. The project, being performed under responsibility of the German Aerospace Center (DLR), is aimed to investigate the behavior and the possibilities of an improved shape for aerospace vehicles considering sharp edges and facetted surfaces. It is a basic in-flight experimentation research on hypersonic technologies for future launcher vehicles but not a re-entry experiment. Additionally, the SHEFEX-I project is the starting point for a series of experiments which enable the acquisition of important knowledge in hypersonic free flight experimentation and which are an excellent test bed for new technological concepts. The experiment which successfully flew on top of a two-stage solid propellant sounding rocket on October 27th, 2005 from Andøya Rocket Range in northern Norway, enabled time accurate investigation of the flow effects and their structural answer during a hypersonic flight Ma~6 from 90 km down to an altitude of 20 km. The present paper gives an overview about the aerothermodynamic philosophy and introduces some main outcomes of the post-flight analysis
Scheduling and routing models for airline systems
No full textDecember 1969PB 196 528Includes bibliographical referencesForeword: This report attempts to put together all of the optimal computer models concerned with scheduling and routing problems for passenger transportation systems. By placing them in one place, classifying them, and using a consistent notation, it is hoped that the models' relationships to each other can be seen, and that a clear picture of the state of the art in model building and solving can be shown. The emphasis of the report is on optimal models which use well-known optimization techniques from mathematical programming. Work which uses heuristic computer methods in this area is quite extensive, but is not described here. The models are oriented towards public transportation systems operati-ng on a short haul network. Generally a cyclic or repetitive schedule of services is assumed, and a single vehicle rather than a train of vehicles is being dispatched. Within those assumptions, the models can find applicability to schedule planning for a wide range of public transportation systems, not necessarily just airline systems. The research is supported in part by the Office of High Speed Ground Transportation, Department of Transportation, and is pointed towards producing schedules for both high speed trains and future V/STOL aircraft. The models are useful to planners and regulators in studying problems in corporate planning, in transportation systems planning, and in regulation of transportation industries. An extensive bibliography accompanies each class of models in this report. If it is not complete (with respect to optimal models), I would appreciate receiving additional references from interested readers. One of the reasons for writing this report is to give a good bibliography for various groups of present researchers who seem to be unaware of segments of the literature, or of each other's activities. Much of the content of this report has been taken from lecture notes prepared by the author for an MIT graduate course, "Flight Transportation Operations Analysis", given by the author for the past few years. Students from that course will recognize the examples as being homework problems involving "Tech Airways", and I am indebted to them since some of their computer solutions are used as examples in the report. As well, the report gives an overview of current research activity in this area in the MIT Flight Transportation Laboratory. A previous report, FTL R68-5 by Professor Amos Levin describes some of the Fleet Routing models and computational methods for solving them. Other reports and theses from the laboratory are referenced where appropriate. I must also recognize the work performed by Dave Benbasset, Norm Clerman, and Thor Paalson in providing computer runs for several of the examples. i
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
A syntax of hoverfly flight prototypes
No full textGeurten B, Kern R, Braun E, Egelhaaf M. A syntax of hoverfly flight prototypes. Journal of Experimental Biology. 2010;213(14):2461-2475.Hoverflies such as Eristalis tenax Linnaeus are known for their distinctive flight style. They can hover on the same spot for several seconds and then burst into movement in apparently any possible direction. In order to determine a quantitative and structured description of complex flight manoeuvres, we searched for a set of repeatedly occurring prototypical movements (PMs) and a set of rules for their ordering. PMs were identified by applying clustering algorithms to the translational and rotational velocities of the body of Eristalis during free-flight sequences. This approach led to nine stable and reliable PMs, and thus provided a tremendous reduction in the complexity of behavioural description. This set of PMs together with the probabilities of transition between them constitute a syntactical description of flight behaviour. The PMs themselves can be roughly segregated into fast rotational turns (saccades) and a variety of distinct translational movements (intersaccadic intervals). We interpret this segregation as reflecting an active sensing strategy which facilitates the extraction of spatial information from retinal image displacements. Detailed analysis of saccades shows that they are performed around all rotational axes individually and in all possible combinations. We found the probability of occurrence of a given saccade type to depend on parameters such as the angle between the long body axis and the direction of flight
Flight Capital and its Reversal for Development Financing
No full textcapital flight, flight capital reversal, development finance
Capital flight, external debt, and domestic policies
No full textThe international debt crisis of 1982 revealed that unrecorded private capital outflows from developing countries occurred simultaneously with borrowing from international commercial banks. Current interest in capital flight has been generated by the possibility that the resurgence of private capital inflows to these countries may be limited to the return of flight capital. A simple public finance model shows that simultaneous capital outflows and inflows can be explained as the result of private international arbitrage of domestic policies. The paper discusses the welfare consequences of gross two-way capital flows that take advantage of opportunities to avoid taxation or generate subsidy income.Capital movements ; Developing countries ; Finance, Public
Sounding Rockets for Entry Research: SHEFEX Flight Test Program
No full textWithin research for space vehicles with Re-entry capability and hypersonic airplane development in the last decade sounding rocket systems became a major and important test bed. This paper will present an overview of the national development and flight test program SHEFEX (SHARP EDGE FLIGHT EXPERIMENT) of the German Aerospace Center DLR. After 2 successful flight campaigns in 2005 and 2012 DLR is now preparing the next test vehicle SHEFEX III, which is planned for launch in 2016. The paper will focus on the strategic test approach and scientific experiments on board in interaction and possibilities of the sounding rocket system. Also some spin off effects will be prescribed which will enhance the performance of the rocket system also outside re-entry research
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Air Force Flight Dynamics Laboratory (U.S.) Technical Report 73-19 Volume V. Part I
No full textReport describing a program of flight control technology applicable to an Advance Medium STOL Transport (AMST) airplane equipped with a vectored-thrust powered lift system. Low q moment producers are evaluated. Mathematical models (control laws) of control systems suitable for the STOL landing approach are defined. The effect of control system mechanization complexity on performance, weight, cost, safety, design risk, and vulnerability to small arms fire are evaluated. A candidate control system is selected and its performance is validated using a piloted moving base simulation. (Author)
Capital Flight from the Philippines, 1962-1986
No full textThis paper presents quantitative measures of the annual flow and cumulative stock of capital flight from the Philippines from 1962-1986. Results indicate a substantial capital flight during the period of investigation, amounting to almost four-fifths of the country’s external debt outstanding at the end of 1986.inflows, capital outflows, public debt, capital account
Application of robust control in unmanned vehicle flight control system design
No full textThe robust loop-shaping control methodology is applied in the flight control system
design of the Cranfield A3 Observer unmanned, unstable, catapult launched air vehicle.
Detailed linear models for the full operational flight envelope of the air vehicle are
developed. The nominal and worst-case models are determined using the v-gap metric.
The effect of neglecting subsystems such as actuators and/or computation delays on
modelling uncertainty is determined using the v-gap metric and shown to be significant.
Detailed designs for the longitudinal, lateral, and the combined full dynamics TDF
controllers were carried out. The Hanus command signal conditioning technique is also
implemented to overcome actuator saturation and windup. The robust control system is
then successfully evaluated in the high fidelity 6DOF non-linear simulation to assess its
capability of launch stabilization in extreme cross-wind conditions, control
effectiveness in climb, and navigation precision through the prescribed 3D flight path in
level cruise. Robust performance and stability of the single-point non-scheduled control
law is also demonstrated throughout the full operational flight envelope the air vehicle
is capable of and for all flight phases and beyond, to severe launch conditions, such as
33knots crosswind and exaggerated CG shifts.
The robust TDF control law is finally compared with the classical PMC law where the
actual number of variables to be manipulated manually in the design process are shown
to be much less, due to the scheduling process elimination, although the size of the final
controller was much higher. The robust control law performance superiority is
demonstrated in the non-linear simulation for the full flight envelope and in extreme
flight conditions
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