326 research outputs found
Investigation of installation effects on twin-engine convergent-divergent nozzles
An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine installation effects on convergent-divergent nozzles applicable to twin-engine reduced-power supersonic cruise aircraft. Tests were conducted at Mach numbers from 0.50 to 1.20, angles of attack from -5 deg to 9 deg, and at nozzle pressure ratios from jet off (1.0) to 8.0. The effects of empennage arrangement, nozzle length, and afterbody closure on total and component drag coefficients were investigated
Effect of simulated in-flight thrust reversing on vertical-tail loads of F-18 and F-15 airplane models
Investigations were conducted in the Langley 16-Foot Transonic Tunnel to provide data on a 0.10-scale model of the prototype F-18 airplane and a 0.047-scale model of the F-15 three-surface configuration (canard, wing, and horizontal tails). Test data were obtained at static conditions and at Mach numbers from 0.6 to 1.2 over an angle-of-attack range from 2 deg to 15 deg. Nozzle pressure ratio was varied from jet off to about 8.0
ESTIMATING RETURNS TO AGRICULTURAL RESEARCH, EXTENSION, AND TEACHING AT THE STATE LEVEL
The majority of decisions concerning investment and allocation of public funds for agricultural research, extension, and teaching (RET) are made at the state-level, while most of the quantitative RET evaluations are made on a national basis. This paper illustrates an approach for conducting a disaggregated state-level evaluation of agricultural research, extension, and teaching. Ridge regression is employed to handle multicollinearity problems.Teaching/Communication/Extension/Profession,
Data reduction formulas for the 16-foot transonic tunnel: NASA Langley Research Center, revision 2
The equations used by the 16-Foot Transonic Wind Tunnel in the data reduction programs are presented in nine modules. Each module consists of equations necessary to achieve a specific purpose. These modules are categorized in the following groups: (1) tunnel parameters; (2) jet exhaust measurements; (3) skin friction drag; (4) balance loads and model attitudes calculations; (5) internal drag (or exit-flow distribution); (6) pressure coefficients and integrated forces; (7) thrust removal options; (8) turboprop options; and (9) inlet distortion
Effects of the installation and operation of jet-exhaust yaw vanes on the longitudinal and lateral-directional characteristics of the F-14 airplane
A wind tunnel investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effects of the installation and use of jet exhaust yaw vanes on the longitudinal and lateral-directional characteristics of the F-14 aircraft. The model was tested at Mach numbers from 0.70 to 1.25 at angles of attack from 0 deg to 4.3 deg. Compressed air was used to simulate nozzle exhaust flow from jet off up to a nozzle pressure ratio of 8. The results of the investigation show that the yaw vanes can augment the rudders to provide directional control, but further investigation will be necessary to optimize the deflection schedule associated with the various nozzle power settings
Computations for the 16-foot transonic tunnel, NASA, Langley Research Center, revision 1
The equations used by the 16 foot transonic tunnel in the data reduction programs are presented in eight modules. Each module consists of equations necessary to achieve a specific purpose. These modules are categorized in the following groups: tunnel parameters; jet exhaust measurements; skin friction drag; balance loads and model attitudes calculations; internal drag (or exit-flow distributions); pressure coefficients and integrated forces; thrust removal options; and turboprop options. This document is a companion document to NASA TM-83186, A User's Guide to the Langley 16 Foot Transonic Tunnel, August 1981
Opportunistic survey of leucistic individuals of the Southern Crested-Caracara (Caracara Plancus) in the Patagonia Austral Park (Chubut, Argentina)
En este trabajo se reporta el primer conteo parcial de individuos leucísticos de Carancho (Caracara plancus) dentro del Parque Interjurisdiccional Marino Costero Patagonia Austral, Chubut, Argentina. Entre septiembre de 2016 y enero de 2017 se recorrieron 1325 km dentro del parque. Durante los recorridos se divisó, aproximadamente a 2 km de la costa de Bahía Melo, a un grupo de 66 individuos de Carancho asociados a los restos de caza de guanacos, de los cuales 36 eran de coloración clara (5 de coloración intermedia y 31 leucísticos). Estos registros incrementan la información disponible sobre esta particular población con aberraciones cromáticas.In this work we report the first partial survey of leucistic individuals of the Southern Crested-Caracara (Caracara plancus) in the Interjurisdictional Marine Park of Patagonia Austral, Chubut, Argentina. Between September 2016 and January 2017, 1325 km were surveyed within the park. During the survey, we sighted a group of 66 individuals of the Southern Crested-Caracara, approximately 2 km from the coast of Bahía Melo, associated with the remains of guanaco hunting, of which 36 were lightly coloured (5 of intermediate coloration and 31 leucistic). These records increase the information available about this particular population with chromatic aberrations
Negative-Index Metamaterials: Second-Harmonic Generation, Manley-Rowe Relations and Parametric Amplification
Second harmonic generation and optical parametric amplification in
negative-index metamaterials (NIMs) are studied. The opposite directions of the
wave vector and the Poynting vector in NIMs results in a "backward"
phase-matching condition, causing significant changes in the Manley-Rowe
relations and spatial distributions of the coupled field intensities. It is
shown that absorption in NIMs can be compensated by backward optical parametric
amplification. The possibility of distributed-feedback parametric oscillation
with no cavity has been demonstrated. The feasibility of the generation of
entangled pairs of left- and right-handed counter-propagating photons is
discussed.Comment: 7 pages, 6 figure
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