| Energy Transport in the Thermosphere During the Solar Storms of April 2002 |
15 DEC 2005 |
20 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| DSMC Simulations of Hypersonic Flows and Comparison With Experiments |
13 JUL 2005 |
7 pages |
| Authors:
James N. Moss; Graeme A. Bird; Gennady N. Markelov; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
 | This paper presents computational results obtained with the direct simulation Monte Carlo (DSMC) method for several biconic test cases in which shock interactions and flow separation-reattachment are key features of the flow. Recent ground-based experiments have been performed for several biconic configurations and surface heating rate and pressure measurements have been proposed for code validation studies. The present focus is to expand on the current validating activities for a relatively ... |
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| Free-to-Roll Investigation of the Pre-Production F/A-18E Powered Approach Wing Drop |
11 APR 2005 |
9 pages |
| Authors:
D. B. Owens; Elaine M. Bryant; Jewel B. Barlow; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| A free-to-roll study of the low-speed lateral characteristics of the pre-production F/A-18E was conducted in the NASA Langley 12-Foot Low-Speed Tunnel. In developmental flight tests the F/A-18E unexpectedly experienced uncommanded lateral motions in the power approach configuration. The objective of this study was to determine the feasibility of using the free-to-roll technique for the detection of uncommanded lateral motions for the pre- production F/A-18E in the power approach configuration. The ... |
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| Characterization of Meta-Materials Using Computational Electromagnetic Methods |
JAN 2005 |
5 pages |
| Authors:
Manohar Deshpande; Joon Shin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| An efficient and powerful computational method is presented to characterize a meta-material in terms of its specified electromagnetic properties. Using the periodicity of meta-materials, the Finite Element Methodology (FEM) is developed to estimate reflection and transmission through the meta-material structure for a normal plane wave incidence. For efficient computations of reflection and transmission through a meta-material over a wideband frequency range, a Finite Difference Time Domain (FDTD) approach is developed. ... |
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| Hypersonic Boundary/Shear Layer Transition for Blunt to Slender Configurations - A NASA Langley Experimental Perspective |
01 OCT 2004 |
35 pages |
| Authors:
Thomas J. Horvath; Scott A. Berry; N. R. Merski; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Heating augmentations and temperature increases resulting from boundary layer/shear layer transition during hypersonic flight through the atmosphere of Earth or other planets impose critical constraints on the design of vehicle thermal protection systems and are well documented in the literature. Laminar-to-turbulent transition effects on local surface heat transfer determine thermal protection system material selection, placement, and thickness. In terms of vehicle performance, transition can influence vehicle aerodynamics and scramjet propulsion ... |
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| A Design of Experiments Approach Defining the Relationships Between Processing and Microstructure for Ti-6Al-4V |
AUG 2004 |
12 pages |
| Authors:
T. A. Wallace; K. S. Bey; K. M. Taminger; R. A. Hafley; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| A study was conducted to evaluate the relative significance of input parameters on Ti- 6A1-4V deposits produced by an electron beam freeform fabrication process under development at the NASA Langley Research Center. Five input parameters where chosen (beam voltage beam current, translation speed, wire feed rate, and beam focus), and a design of experiments (DOE) approach was used to develop a set of 16 experiments to evaluate the relative importance ... |
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| Effect of Surface Treatments on Electron Beam Freeform Fabricated Aluminum Structures |
AUG 2004 |
11 pages |
| Authors:
Karen M. Taminger; Robert A. Hafley; David T. Fahringer; Richard E. Martin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| Electron beam freeform fabrication (EBF3) parts exhibit a ridged surface finish typical of many layer-additive processes. Thus, post-processing is required to produce a net shape with a smooth surface finish. High speed milling, wire electrical discharge machining (EDM), electron beam glazing, and glass bead blasting were performed on EBF(3)-built 2219 aluminum alloy parts to reduce or eliminate the ridged surface features. Surface roughness, surface residual stress state, and microstructural characteristics ... |
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| Development of Nickel-Titanium Graded Composition Components |
AUG 2004 |
14 pages |
| Authors:
M. S. Domack; J. M. Baughman; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| The potential of various manufacturing methods was evaluated for producing nickel-titanium graded composition material. The selected test case examined attachment brackets that join nickel-based metallic thermal protection systems to titanium-based launch vehicle structure. The proposed application would replace nickel-based components with graded composition components in an effort to alleviate service induced thermal stresses. Demonstration samples were produced by laser direct metal deposition, flat wire welding, and ultrasonic consolidation. Microstructure, general ... |
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| Technical Training on High-Order Spectral Analysis and Thermal Anemometry Applications |
SEP 2003 |
14 pages |
| Authors:
A. A. Maslov; A. N. Shiplyuk; A. A. Sidirenko; D. A. Bountin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| The topics of thermal anemometry and high-order spectral analyses were the subject of the technical training. Specifically, the objective of the technical training was to study: (i) the recently introduced constant voltage anemometer (CVA) for high-speed boundary layer; and (ii) newly developed high- order spectral analysis techniques (HOSA). Both CVA and HOSA are relevant tools for studies of boundary layer transition and stability. |
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| Control of Interacting Vortex Flows at Subsonic and Transonic Speeds Using Passive Porosity |
MAR 2003 |
9 pages |
| Authors:
Gary E. Erickson; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| A wind tunnel experiment was conducted in the NASA Langley Research Center (LaRC) 8-foot Transonic Pressure Tunnel (TPT) to determine the effects of passive surface porosity on vortex flow interactions about a general research fighter configuration at subsonic and transonic speeds. Flow-through porosity was applied to a wind leading-edge extension (LEX) mounted to a 65 deg cropped delta wind model to promote large nose-down pitching moment increments at high angles ... |
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| Cranked Arrow Wing (F-16XL-1) Flight Flow Physics with CFD Predictions at Subsonic and Transonic Speeds |
MAR 2003 |
21 pages |
| Authors:
John E. Lamar; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| The increasing capability of computational fluid dynamics (CFD) to simulate real airplane geometries and flow conditions is found in the literature for both fighter and transport airplanes. In the continuance of that trend, this report details the results of a comparative study of CFD and flight data for the F-16XL-1 airplane over a wide range of test conditions from transonic to subsonic speeds. Though this airplane is not new, its ... |
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| Technical Evaluation Report, Part A - Vortex Flow and High Angle of Attack |
MAR 2003 |
27 pages |
| Authors:
James M. Luckring; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| A symposium entitled Vortex Flow and High Angle of Attack was held in Loen, Norway, from May 7 through May 11, 2001. The Applied Vehicle Technology (AVT) Panel, under the auspices of the Research and Technology Organization (RTO), sponsored this symposium. Forty-eight papers, organized into nine sessions, addressed computational and experimental studies of vortex flows pertinent to both aircraft and maritime applications. The studies also ranged from fundamental fluids investigations ... |
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| In-Flight Flow Visualization Results of the F-106B with a Vortex Flap |
MAR 2003 |
35 pages |
| Authors:
Jay M. Brandon; James B. Hallissy; Philip W. Brown; John E. Lamar; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Surface and off-surface flow visualization techniques were used to visualize the three-dimensional vortex flows on the F-106 aircraft with vortex flaps installed. Results at angles of attack between 9 degrees and 18 degrees and Mach numbers from 0.3 to 0.9 are presented. A smoke flow vapor screen technique was used to document leading-edge vortex paths and sizes, while an oil flow technique was employed to provide detailed information on reattachment ... |
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| Vortical Flow Prediction Using an Adaptive Unstructured Grid Method |
MAR 2003 |
37 pages |
| Authors:
Shahyar Z. Pirzadeh; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| A computational fluid dynamics (CFD) method has been employed to compute vortical flows around slender wing/body configurations. The emphasis of the paper is on the effectiveness of an adaptive grid procedure in capturing' concentrated vortices generated at sharp edges or flow separation lines of lifting surfaces flying at high angles of attack. The method is based on a tetrahedral unstructured grid technology developed at the NASA Langley Research Center. Two ... |
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| Advances in Structural Integrity Analysis Methods for Aging Metallic Airframe Structures with Local Damage |
FEB 2003 |
16 pages |
| Authors:
James H. Starnes Jr.; James C. Newman Jr.; Charles E. Harris; Robert S. Piascik; Richard D. Young; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| Analysis methodologies for predicting fatigue-crack growth from rivet holes in panels subjected to cyclic loads and for predicting the residual strength of aluminum fuselage structures with cracks and subjected to combined internal pressure and mechanical loads are described. The fatigue-crack growth analysis methodology is based on small-crack theory and a plasticity induced crack-closure model, and the effect of a corrosive environment on crack-growth rate is included. The residual strength analysis ... |
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| Molecular Dynamics Simulations on Nanocomposites Formed by Intermetallic Dispersoids of L1(2) Type and Aluminum Matrices |
2003 |
6 pages |
| Authors:
Min Namkung; Sun M. Paik; Buzz Wincheski; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Molecular dynamics simulations were performed to characterize the lattice morphology in the region adjacent to the interfaces in nanocomposite systems of a Ni3Al dispersoid embedded in Al matrix (Ni3Al/Al) and an Al3Nb dispersoid embedded in aluminum matrix (Al3Nb/Al). A nearly perfect coherent interface is obtained in the Al3Nb/Al system with the lattice planes of dispersoid and matrix aligned parallel in all directions. The simulation results show the presence of the ... |
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| Simulation of Carbon Nanotube Pull-out When Bonded to a Polymer Matrix |
2003 |
6 pages |
| Authors:
S. J. Frankland; V. M. Harik; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| A carbon nanotube pulling through a polyethylene matrix was simulated using molecular dynamics. The interfacial sliding was characterized in terms of a nanoscale friction model, which is parametrized from the molecular dynamics simulation, and involves determining the critical pull-out force on the nanotube and the effective viscosity at the nanotube/polymer interface. Comparison was made of the pull-out behavior of non-bonded and functionalized nanotube composites. Chemical bonds between the polymer and ... |
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| P1 Nonconforming Finite Element Method for the Solution of Radiation Transport Problems |
AUG 2002 |
24 pages |
| Authors:
Kab S. Kang; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| The simulation of radiation transport in the optically thick flux- limited diffusion regime has been identified as one of the most time-consuming tasks within large simulation codes. Due to multimaterial complex geometry, the radiation transport system must often be solved on unstructured grids. In this paper, we investigate the behavior and the benefits of the unstructured P sub 1 nonconforming finite element method, which has proven to be flexible and ... |
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| Uncertainty Analysis for Fluid Mechanics with Applications |
FEB 2002 |
50 pages |
| Authors:
Robert W. Walters; Luc Huyse; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| This paper reviews uncertainty analysis methods and their application to fundamental problems in fluid dynamics. Probabilistic (Monte-Carlo, Moment methods, Polynomial Chaos) and non-probabilistic methods (Interval Analysis Propagation of error using sensitivity derivatives) are described and implemented. Results are presented for a model convection equation with a source term, a model non-linear convection-diffusion equation; supersonic flow over wedges, expansion corners, and an airfoil; and two-dimensional laminar boundary layer flow. |
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| Wind Tunnel Evaluation of a Model Helicopter Main-Rotor Blade With Slotted Airfoils at the Tip |
DEC 2001 |
132 pages |
| Authors:
Kevin W. Noonan; William T. Yeager Jr.; Jeffrey D. Singleton; Matthew L. Wilbur; Paul H. Mirick; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| Data for rotors using unconventional airfoils are of interest to permit an evaluation of this technology's capability to meet the U.S. Army's need for increased helicopter mission effectiveness and improved safety and survivability. Thus, an experimental investigation was conducted in the Langley Transonic Dynamics Tunnel (TDT) to evaluate the effect of using slotted airfoils in the rotor blade tip region (85 to 100 percent radius) on rotor aerodynamic performance and ... |
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| On the Conservation and Convergence to Weak Solutions of Global Schemes |
Dec 2001 |
19 pages |
| Authors:
Mark H Carpenter; David Gottlieb; Chi-Wang Shu; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| In this paper we discuss the issue of conservation and convergence to weak solutions of several global schemes including the commonly used compact schemes and spectral collocation schemes, for solving hyperbolic conservation laws. It is shown that such schemes, if convergent boundedly almost everywhere, will converge to weak solutions. The results are extensions of the classical Lax-Wendroff theorem concerning conservative schemes. |
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| Blending Methodology of Linear Parameter Varying Control Synthesis of F- 16 Aircraft System |
OCT 2001 |
24 pages |
| Authors:
Jong-Yeob Shin; Gary J. Balas; Alpay M. Kaya; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| This paper presents the design of a linear parameter varying (LPV) controller for the F-16 longitudinal axes over the entire flight envelope using a blending methodology which lets an LPV controller preserve performance level over each parameter subspace and reduces computational costs for synthesizing an LPV controller. Three blending LPV controller synthesis methodologies are applied to control F-16 longitudinal axes. Using a function substitution method, a quasi-LPV model of the ... |
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| Random Field Solutions Including Boundary Condition Uncertainty for the Steady-state Generalized Burgers Equation |
OCT 2001 |
28 pages |
| Authors:
Luc Huyse; Robert W. Walters; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| CFD results are subject to considerable uncertainty associated with the operating conditions. Even when the operational uncertainty is omitted under very controlled circumstances during wind tunnel experiments, substantial disagreement between experimental and CFD results persists. This discrepancy must be attributed to model uncertainty. This report discusses the various sources of uncertainty. The need for advanced uncertainty modeling is illustrated by means of a computationally inexpensive 1-D Burgers equation model. We ... |
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| Analysis of Linear Parameter Varying System Models Based on Reachable Sets |
OCT 2001 |
19 pages |
| Authors:
Jong-Yeob Shin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| This paper presents the analysis method of quasi-LPV models, comparing the ellipsoid set which contains the reachable set of a nonlinear system to define which quasi-LPV model is less conservative to represent the nonlinear dynamics. Three quasi-LPV models are constructed from a nonlinear model using three different methods, to facilitate synthesis of an LPV controller for the nonlinear system. The comparison results of closed-loop system performance with synthesized LPV controllers ... |
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| The Solution of Radiation Transport Equations with Adaptive Finite Elements |
OCT 2001 |
17 pages |
| Authors:
Linda Stals; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| We compare the performance of an inexact Newton-multigrid method and Full Approximation Storage multigrid when solving radiation transport equations. We also present an adaptive refinement algorithm and explore its impact on the solution of such equations. |
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| Robust Airfoil Optimization to Achieve Consistent Drag Reduction Over a Mach Range |
AUG 2001 |
23 pages |
| Authors:
Wu Li; Luc Hyuse; Sharon Padula; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| We prove mathematically that in order to avoid point-optimization at the sampled design points for multipoint airfoil optimization, the number of design points must be greater than the number of free-design variables. To overcome point-optimization at the sampled design points, a robust airfoil optimization method (called the profile optimization method) is developed and analyzed. This optimization method aims at a consistent drag reduction over a given Mach range and has ... |
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| Large Eddy and Detached Eddy Simulations Using an Unstructured Multigrid Solver |
AUG 2001 |
10 pages |
| Authors:
Dimitri J. Mavriplis; Juan Pelaez; Osama Kandil; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| This work is concerned with the development of an efficient parallel Large Eddy Simulation (LES) and Detached Eddy Simulation (DES) capability using unstructured meshes. The advantages of unstructured meshes include flexible modeling of complex geometries, adaptive meshing capabilities, and homogeneous data structures well suited for massively parallel computer architectures. On the other hand, unstructured mesh techniques require additional computer resources as compared to cartesian or structured mesh methods, and the ... |
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| Lattice Boltzmann Method for Turbulent Combustion |
19 JUN 2001 |
4 pages |
| Authors:
Sharath S. Girimaji; Li-Shi Luo; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Over the last few years, the Lattice Boltzmann methods - Lattice Boltzmann Equation (LBE) and Lattice Gas Automata (LGA) have made significant strides in both theory and application. On the theoretical front, rigorous mathematical proof now exists demonstrating that the LBE method is a special finite difference scheme of the Boltzmann equation that governs all fluid flow %1. (Recall that the Navier-Stokes equation also has its basis in the Boltzmann ... |
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| Active Control Technology at NASA Langley Research Center |
JUN 2001 |
14 pages |
| Authors:
Richard R. Antcliff; Ann-Marie R. McGowan; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| NASA Langley has a long history of attacking important technical opportunities from a broad base of supporting disciplines. The research and development at Langley in this subject area range from the test tube to the test flight. The information covered here will range from the development of Innovative new materials sensors and actuators to the incorporation of smart sensors and actuators in practical devices to the optimization of the location ... |
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| ICASE Semiannual Report |
MAY 2001 |
60 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| This report summarizes research conducted at ICASE in applied mathematics, computer science, fluid mechanics, and structures and material sciences during the period October 1, 2000 through March 31, 2001. |
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| Semiannual Report: April 1, 2000 Through September 20, 2000 |
JAN 2001 |
67 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| ICASE is operated at the Langley Research Center (LaRC) of NASA by the Universities Space Research Association (USRA) under a contract with the Center. USRA is a nonprofit consortium of major U.S. colleges and universities. The Institute conducts unclassified basic research in applied mathematics, numerical analysis and algorithm development, computer science, fluid mechanics, and structures and materials in order to extend and improve problem-solving capabilities in science and engineering, particularly ... |
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| FIELD-DEPLOYABLE ACOUSTIC DIGITAL SYSTEMS FOR NOISE MEASUREMENT, |
JAN 2001 |
|
| Authors:
QAMAR A. SHAMS; KENNETH D. WRIGHT; CHARLES B. LUNSFORD; CHARLIE D. SMITH; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
 | (U) THIS PAPER PRESENTS A DETAILED DESCRIPTION OF TWO SYSTEMS ALONG WITH ACOUSTIC DATA ANALYSIS FROM BOTH SYSTEMS. THE TWO SYSTEMS ARE THE DIGITAL ACOUSTIC MEASUREMENT SYSTEM (DAMS) FOR MEASURING THE ACOUSTIC NOISE LEVELS FROM ROTORCRAFT AND TILTROTOR AIRCRAFT; AND THE REMOTE ACQUISITION AND STORAGE SYSTEM (RASS), DEVELOPED AND DEPLOYED FOR THE FIRST TIME IN THE FIELD ALONG WITH THE DAMS SYSTEM FOR THE COMMUNITY NOISE FLIGHT TEST USING THE ... |
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| Field-Deployable Acoustic Digital Systems for Noise Measurement |
OCT 2000 |
19 pages |
| Authors:
Qamar A. Shams; Kenneth D. Wright; Charles B. Lunsford; Charlie D. Smith; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System (DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System (RASS) was developed and deployed for ... |
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| Future Challenges and Opportunities in Aerodynamics |
SEP 2000 |
19 pages |
| Authors:
Ajay Kumar; Jerry N. Hefner; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Investments in aeronautics research and technology have declined substantially over the last decade, in part due to the perception that technologies required in aircraft design are fairly mature and readily available. This perception is being driven by the fact that aircraft configurations, particularly the transport aircraft, have evolved only incrementally over last several decades. If, however, one considers that the growth in air travel is expected to triple in the ... |
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| Steady and Periodic Pressure Measurements on a Generic Helicopter Fuselage Model in the Presence of a Rotor |
JUN 2000 |
188 pages |
| Authors:
Raymond E. Mineck; Susan A. Gorton; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Helicopter airframes are subjected to periodic air-loads due principally to the rotating main rotor blades. The periodic air loads impact the noise and vibration within the passenger cabin as well as the fatigue life of the airframe. Computational techniques have been and are being developed to predict these periodic airframe air loads. Periodic pressure measurements are needed on simple configurations for validation of the computational techniques. Few experimental data sets ... |
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| Exploratory Investigation of Aerodynamic Characteristics of Helicopter Tail Boom Cross-Section Models With Passive Venting |
JUN 2000 |
53 pages |
| Authors:
Daniel W. Banks; Henry L. Kelly; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Two large-scale two-dimensional helicopter tail boom models were used to determine the effects of passive venting on boom down loads and side forces in hovering crosswind conditions. The models were oval shaped and trap- ezoidal shaped. Completely porous and solid configurations partial venting in various symmetric and asymmetric configurations and strakes were tested. Calculations were made to evaluate the trends of venting and strakes on power required when applied to ... |
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| Development of X-33/X-34 Aerothermodynamic Data Bases: Lessons Learned and Future Enhancements |
JUN 2000 |
12 pages |
| Authors:
C. G. Miller; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| A synoptic of programmatic and technical lessons learned in the development of aerothermodynamic data bases for the X-33 and X-34 programs is presented in general terms and from the perspective of the NASA Langley Research Center Aerothermodynamics Branch. Aerothermodynamics, defined herein as encompassing aerodynamics, aeroheating, and fluid dynamics and physical processes, is the genesis for the design, development, and flight of space transportation vehicles and is in the critical path ... |
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| Research Activities Within NASA's Morphing Program |
MAY 2000 |
10 pages |
| Authors:
Anna-Maria R. McGowan; Lucas G. Horta; Joycelyn S. Harrison; David L. Raney; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| In the last decade, smart technologies have become important enabling technologies that cut across traditional boundaries in science and engineering. Here smart is defined as the ability to respond to a stimulus in a predictable and reproducible manner. while multiple successes have been achieved in the laboratory, we have yet to see the general applicability of smart technologies to actual aircraft and spacecraft. The NASA Morphing program is an attempt ... |
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| NASA Langley Research Center's Contributions to International Active Buffeting Alleviation Programs |
MAY 2000 |
9 pages |
| Authors:
Robert W. Moses; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Buffeting is an aeroelastic phenomenon which plagues high performance aircraft, especially those with twin vertical tails like the F/A-18, at high angles of attack. This buffeting is a concern from fatigue and inspection points of view. By means of wind-tunnel and flight tests, this phenomenon is well studied to the point that buffet loads can be estimated and fatigue life can be increased by structural enhancements to the airframe. In ... |
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| Flow Environment Study Near the Empennage of a 15-Percent Scale Helicopter Model |
MAR 2000 |
30 pages |
| Authors:
Susan A. Gorton; John D. Berry; W. T. Hodges; Deane G. Reis; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Development of advanced rotorcraft configurations has highlighted a need for high-qualify experimental data to support the development of flexible and accurate analytical design tools. To provide this type of data a test program was conducted in the Langley 14- by 22-Foot Subsonic Tunnel to measure the flow near the empennage of a 1 5-percent scale powered helicopter model with an operating tail fun. Three-component velocity profiles were measured with laser ... |
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| Field-Deployable Acoustic Digital Systems for Noise Measurement |
2000 |
19 pages |
| Authors:
Qamar A. Shams; Kenneth D. Wright; Charles B. Lunsford; Charlie D. Smith; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System(DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System(RASS) was developed and deployed for the first ... |
|
| Analyzing Mode Confusion via Model Checking |
MAY 1999 |
67 pages |
| Authors:
Gerald Luettgen; Victor Carreno; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Mode confusion is one of the most serious problems in aviation safety. Today's complex digital flight decks make it difficult for pilots to maintain awareness of the actual states, or modes, of the flight deck automation. NASA Langley leads an initiative to explore how formal techniques can be used to discover possible sources of mode confusion. As part of this initiative, a flight guidance system was previously specified as a ... |
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| A Comparison of Interactional Aerodynamics Methods for a Helicopter in Low Speed Flight |
JUN 1998 |
17 pages |
| Authors:
John D. Berry; Victor Leinikov; Irene Bavykina; Mark S. Chaffin; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Recent advances in computing subsonic flow have been applied to helicopter configurations with various degrees of success. This paper is a comparison of two specific methods applied to a particularly challenging regime of helicopter flight, very low speeds, where the interaction of the rotor wake and the fuselage are most significant. Comparisons are made between different methods of predicting the interactional aerodynamics associated with a simple generic helicopter configuration. These ... |
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| Full-Potential Modeling of Blade-Vortex Interactions |
DEC 1997 |
90 pages |
| Authors:
Henry E. Jones; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| A study of the full-potential modeling of a blade-vortex interaction was made. A primary goal of this study was to investigate the effectiveness of the various methods of modeling the vortex. The model problem restricts the interaction to that of an infinite wing with an infinite line vortex moving parallel to its leading edge. This problem provides a convenient testing ground for the various methods of modeling the vortex while ... |
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| Aerospace Medicine and Biology: A Continuing Bibliography With Indexes |
20 OCT 1997 |
36 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| This issue of Aerospace Medicine and Biology, A Continuing Bibliography with Indexes NASA SP-7O11 lists reports, articles, and other documents recently announced in the NASA STI Database. In its subject coverage, Aerospace Medicine and Biology concentrates on the biological, physiological, psychological, and environmental effects to which humans are subjected during and following simulated or actual flight in the Earth's atmosphere or in interplanetary space. References describing similar effects on biological ... |
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| Performance and Vibratory Loads Data from a Wind-Tunnel Test of a Model Helicopter Main-Rotor Blade with a Paddle-Type Tip |
MAY 1997 |
26 pages |
| Authors:
William T. Yeager Jr.; Kevin W. Noonan; Jeffrey D. Singleton; Matthew L. Wilbur; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| An investigation was conducted in the Langley Transonic Dynamics Tunnel to obtain data to permit evaluation of paddle-type tip technology for possible use in future U.S. advanced rotor designs. Data were obtained for both a baseline main-rotor blade and a main-rotor blade with a paddle-type tip. The baseline and paddle-type tip blades were compared with regard to rotor performance oscillatory pitch-link loads and 4-per-rev vertical fixed-system loads. Data were obtained ... |
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| Fatigue Debonding Characterization in Composite Skin/Stringer Configurations |
APR 1997 |
37 pages |
| Authors:
Michael K. Cvitkovich; T. K. O'Brien; Pierre J. Minguet; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| The objective of this work was to investigate the fatigue damage mechanisms and to identify the influence of skin stacking sequence in carbon epoxy composite bonded skin/stringer constructions. A simple 4-point-bending test fixture originally designed for previously performed monotonic tests was used to evaluate the fatigue debonding mechanisms between the skin and the bonded frame when the dominant loading in the skin is flexure along the edge of the frame. ... |
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| Unsteady Velocity Measurement Taken Behind a Model Helicopter Rotor Hub in Forward Flight |
MAR 1997 |
248 pages |
| Authors:
John D. Berry; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Drag caused by separated flow behind the hub of a helicopter has an adverse effect on aerodynamic performance of the aircraft. To determine the effect of separated flow on a configuration used extensively for helicopter aerodynamic investigations, an experiment was conducted using a laser velocimeter to measure velocities in the wake of a model helicopter hub operating at Mach-scaled conditions in forward flight. Velocity measurements were taken using a laser ... |
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| Emerging Trends in the Globalization of Knowledge: The Role of the Technical Report in Aerospace Research and Development |
97 |
27 pages |
| Authors:
Thomas E. Pinelli; Vicki L. Golich; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Economists, management theorists, business strategists, and governments alike recognize knowledge as the single most important resource in today's global economy. Because of its relationship to technological progress and economic growth, many governments have taken a keen interest in knowledge; specifically its production, transfer, and use. This paper focuses on the technical report as a product for disseminating the results of aerospace research and development (R&D) and its use and importance ... |
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| Operation Heli-STAR - Atlanta Communications Experiment (ACE). Volume 9 |
DEC 1996 |
65 pages |
| Authors:
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| Operation Heli-STAR (Helicopter Short-Haul Transportation and Aviation Research) was established and operated in Atlanta, Georgia, during the period of the 1996 Centennial Olympic Games. Heli-STAR had three major thrusts: (1) the establishment and operation of a helicopter-based cargo transportation system, (2) the management of low-altitude air traffic in the airspace of an urban area, and (3) the collection and analysis of research and development data associated with items 1 and ... |
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