77 research outputs found

    Status and future plans of the Drones for Aerodynamic and Structural Testing (DAST) program

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    Results from flight tests of the ARW-1 research wing are presented. Preliminary loads data and experiences with the active control system for flutter suppression are included along with comparative results of test and prediction for the flutter boundary of the supercritical research wing and on performance of the flutter suppression system. The status of the ARW-2 research wing is given

    A method for controlling parachute deployment conditions in simulated planetary environments

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    Controlling parachute deployment conditions in simulated planetary environment

    Self-induced balloon motions and their effects on wind data

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    Self-induced balloon motions and effects on wind measurement

    Atmospheric turbulence power spectral measurements to long wavelengths for several meteorological conditions

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    Use of power spectral design techniques for supersonic transports requires accurate definition of atmospheric turbulence in the long wavelength region below the knee of the power spectral density function curve. Examples are given of data obtained from a current turbulence flight sampling program. These samples are categorized as (1) convective, (2) wind shear, (3) rotor, and (4) mountain-wave turbulence. Time histories, altitudes, root-mean-square values, statistical degrees of freedom, power spectra, and integral scale values are shown and discussed

    A perspective on the status of measurement of atmospheric turbulence in the US

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    A perspective on status of measurement of atmospheric turbulence is presented. Details are given for turbulence characteristics measured in four distinct meteorological conditions. The emphasis is on identifying appropriate values of L, the integral scale value in the von Karman expression. On-going activity to measure spanwise gradients of turbulence at low altitudes is described. A resume of the NASA VGH program is given, as well as on-going utilization of flight recorder data on wide-body transports to reconstruct special turbulence encounters. Reference is made to some other activities regarding sensing, measurement, modeling, and alleviation

    Power spectral measurements of clear-air turbulence to long wavelengths for altitudes up to 14,000 meters

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    Measurements of three components of clear air atmospheric turbulence were made with an airplane incorporating a special instrumentation system to provide accurate data resolution to wavelengths of approximately 12,500 m (40,000 ft). Flight samplings covered an altitude range from approximately 500 to 14,000 m (1500 to 46,000 ft) in various meteorological conditions. Individual autocorrelation functions and power spectra for the three turbulence components from 43 data runs taken primarily from mountain wave and jet stream encounters are presented. The flight location (Eastern or Western United States), date, time, run length, intensity level (standard deviation), and values of statistical degrees of freedom for each run are provided in tabular form. The data presented should provide adequate information for detailed meteorological correlations. Some time histories which contain predominant low frequency wave motion are also presented

    Harvests of shame: enduring unfree labour in twentieth century United States, 1933-1964

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    This article reframes the discussion on vulnerable and exploited agricultural labour in twentieth-century United States using the overarching category of unfree labour. In order to do so, it bridges two usually distinct historiographies by linking the phenomenon of ā€˜peonageā€™ during the New Deal, with the one of immigrant contract labour southern Florida, under the H2 visa. Archival research on the practices at the US Sugar Corporation in southern Florida exemplifies this link. This article draws on federal archives, government proceedings, papers of political activists and legal and labour scholarship to argue: firstly, that unfree labour has been an enduring feature of agricultural labour relations at regional level during the twentieth century, through both a transmission and a transformation of practice that had their origin in the control of black emancipated labour; secondly, that the introduction of guest workers under the H2 and Bracero programme meant a modernization in the practices of unfree labour, pivoting on the lack of citizenship rights, racial discrimination, debt at home, and threat of deportation; and, finally, that the failure to recognise forms of legal and economic deprivation and coercion as unfree labour has hurt the ability of the United States to enforce protection of human rights at home
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