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At least 235 records · Page 13

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NASA NTRS1954

The flow past a straight and a swept-wing-body combination and their equivalent bodies of revolution at Mach numbers near 1.0

Tests utilizing the Schlieren method of flow photography have been conducted to provide a comparison of the complete flow fields past a straight and a swept-wing-body combination and the flow fields past their equivalent bodies of revolution at Mach numbers around 1.0. The results indicated that the shock growth and positions on the wing-body combinations were closely reproduced in the flow past the equivalent body.

Lindsey, Walter F↗

NASA NTRS1924

The Distribution of Lift Over Wing Tips and Ailerons

This investigation was carried out in the 5-foot wind tunnel of the Langley Memorial Aeronautical Laboratory for the purpose of obtaining more complete information on the distribution of lift between the ends of wing spars, the stresses in ailerons, and the general subject of airflow near the tip of a wing. It includes one series of tests on four models without ailerons, having square, elliptical, and raked tips respectively, and a second series of positively and negatively raked wings with ailerons adjusted to different settings. The results show that negatively raked tips give a more uniform distribution of air pressure than any of the other three arrangements, because the tip vortex does not disturb the flow at the trailing edge. Aileron loads are found to be less severe on wings with negative application to the calculation of aileron and wing stresses and also to facilitate the proper distribution of load in sand testing. Contour charts show in great detail the complex distribution lift over the wing.

Bacon, David L↗

NASA NTRS1989

Applied transonics at Grumman

A review of several applications of Computational Fluid Dynamics (CFD) to various aspects of aerodynamic design recently carried out at Grumman is presented. The emphasis is placed on project-oriented applications where the ease of use of the methods and short start-to-completion times are required. Applications cover transonic wing design/optimization, wing mounted stores load prediction, transonic buffet alleviation, fuselage loads estimation, and compact offset diffuser design for advanced aircraft configurations. Computational methods employed include extended transonic small disturbance (automatic grid embedding) formulation for analysis/design/optimization and a thin layer Navier-Stokes formulation for both external and internal flow analyses.

Davis, W. H.↗

NASA NTRS1992

Paneling methods with vorticity effects and corrections for nonlinear compressibility

Supersonic panel methods and axisymmetric body-modeling singularity methods are presently combined with corrections for nonlinear flow phenomena to a complete missile, its airbreathing inlets, and wing-body combinations. The computer code LRCDM2 is used as an illustrative example of the methods in question. Attention is given to a preliminary method which employs panels to estimate additive drag and lift acting on supersonic rectangular inlets, as well as to the method used to correct off-body flowfields for the presence of a shock. Examples of missile applications of these methods with the appropriate nonlinear corrections are presented.

Dillenius, Marnix F. E.↗

NASA NTRS1992

Research in robust control for hypersonic vehicles

During the first reporting period research concentrated on finishing the modeling work required for a representative model of a scramjet propulsion system for hypersonic vehicles. An existing hypersonic propulsion code was adjusted to the winged-cone configuration. In this process the complete force and moment calculation was revised. The advantageous feature of the code to account for angle of attack variations was then used to compute the thrust, lift, and pitching moment contributions of the propulsion system not only for various Mach numbers and fuel equivalence ratios, but also for different angles of attack.

Calise, A. J.↗

NASA NTRS1999

Unstructured Grid Euler Method Assessment for Aerodynamics Performance Prediction of the Complete TCA Configuration at Supersonic Cruise Speed

Unstructured grid Euler computations, performed at supersonic cruise speed, are presented for a proposed high speed civil transport configuration, designated as the Technology Concept Airplane (TCA) within the High Speed Research (HSR) Program. The numerical results are obtained for the complete TCA cruise configuration which includes the wing, fuselage, empennage, diverters, and flow through nacelles at Mach 2.4 for a range of angles-of-attack and sideslip. The computed surface and off-surface flow characteristics are analyzed and the pressure coefficient contours on the wing lower surface are shown to correlate reasonably well with the available pressure sensitive paint results, particularly, for the complex shock wave structures around the nacelles. The predicted longitudinal and lateral/directional performance characteristics are shown to correlate very well with the measured data across the examined range of angles-of-attack and sideslip. The results from the present effort have been documented into a NASA Controlled-Distribution report which is being presently reviewed for publication.

Farhad Ghaffari↗

NASA NTRS2005

Recent Progress on the Stretched Lens Array (SLA)

At the last Space Photovoltaic Research and Technology Conference, SPRAT XVII, held during the fateful week of 9/11/01, our team presented a paper on the early developments related to the new Stretched Lens Array (SLA), including its evolution from the successful SCARLET array on the NASA/JPL Deep Space 1 spacecraft. Within the past two years, the SLA team has made significant progress in the SLA technology, including the successful fabrication and testing of a complete four-panel prototype solar array wing (Fig. 1). The prototype wing verified the mechanical and structural design of the rigid-panel SLA approach, including multiple successful demonstrations of automatic wing deployment. One panel in the prototype wing included four fully functional photovoltaic receivers, employing triple-junction solar cells.

O'Neill, Markl↗

NASA NTRS2019

Experimental Investigation of the NASA Common Research Model with a Natural Laminar Flow Wing in the NASA Langley National Transonic Facility

A test of the new NASA Common Research Model with a Natural Laminar Flow (CRMNLF) semispan wing in the NASA Langley National Transonic Facility (NTF) was completed in October 2018. The main focus of this test was the evaluation of the extent of laminar flow on the CRM-NLF wing at various Reynolds numbers and test conditions. During this test, data were acquired at chord Reynolds numbers from 10 to 30 million and at Mach numbers ranging from 0.84 to 0.86. This investigation provided valuable insight into the necessary procedures for laminar flow testing in the NTF. It also significantly advanced the new carbonbased heating layer technique to improve the quality of transition visualization data from temperature sensitive paint (TSP) in a cryogenic wind tunnel.

Rivers, Melissa B.↗

NASA NTRS1981

Transonic flutter study of a wind-tunnel model of an arrow-wing supersonic transport

A 1/20-size, low-speed flutter model of the SCAT-15F complete airplane was tested in a wind-tunnel on cables to simulate a near free-flying condition. Only the model wing and fuselage were flexible. Flutter boundaries were measured for a nominal configuration and a configuration with wing fins removed at Mach numbers M from 0.76 to 1.2. For both configurations, the transonic dip in the wing flutter dynamic pressure q boundary was relatively small and the minimum flutter q occurred near M = 0.92. Removing the wing fins increased the flutter q about 14 percent and changed the flutter mode from symmetric to antisymmetric. Vibration and flutter analyses were made using a finite-element structural representation and subsonic kernel-function aerodynamics. For the nominal configuration, the analysis (using calculated modal data) predicted the experimental flutter q levels within 10 percent but did not predict the correct flutter mode at the higher M. For the configuration without wing fins, the analysis predicted 16 to 36 percent unconservative (higher than experimental) flutter q levels and showed extreme sensitivity to mass shapes.

Ruhlin, C. L.↗

NASA NTRS1952

A Comparison of the Chordwise Pressure Distribution and Spanwise Distribution of Loading at Subsonic Speeds on Two Triangular Wings of Aspect Ratio 2 Having NACA 0005 and 0008 Sections

Measurements of the distribution of surface pressures were made on two wing-body combinations employing a triangular wing having an aspect ratio ratio of 2. The first of these combinations had a wing with the NACA 0008-63 section parallel to the air stream while the wing of the second had the NACA 0005-63 section in the stream direction. The measurements were made for Mach numbers from 0.11 to 0.95 at a constant Reynolds number of 3.0 million. Data were also obtained for Reynolds numbers up to 15.0 million at the lower Mach number. A summary of data obtained from previously published force tests of these same models is also included for completeness of the presentation of the effect of wing thickness.

Smith, Donald W↗

NASA NTRS1935

Ice Prevention on Aircraft by Means of Impregnated Leather Covers, Special Report

The National Advisory Committee for Aeronautics is testing the effectiveness of a method to prevent the formation of ice on airplanes. The system makes use of a leather cover that is attached to the leading edge of the wing. A small tube, attached to the inner surface of the leather, distributes to the leading edge a solution that permeates throughout the leather and inhibits the formation of ice on the surface. About 25 pounds of the liquid per hour would be sufficient to prevent ice from forming on a wing of 50-foot span. The additional gross weight of the system will not be excessive. The tests are not yet completed but the method is thought to be practicable for the wing and it may also be adaptable to the propeller.

Clay, William C.↗

NASA NTRS1938

Improvement of aileron effectiveness by the prevention of air leakage through the hinge gap as determined in flight

A flight investigation was made of the increase in effectiveness of ailerons that can be obtained by preventing flow of air through the wing at the hinges and of the possibility of reducing the aileron operating force by replacing ailerons having normal open hinge gaps with narrower but equally effective ailerons having sealed hinge gaps. Tests were made with a Fairchild 22 airplane with two sizes of plain unbalanced ailerons, one set having a chord equal to 0.18c, and the other chord equal to 0.09c. The results of the investigation show that improvement of the lateral-control effectiveness is obtained by completely preventing the flow of air through the wing at the hinge axis of conventional ailerons. The magnitude of the improvement depends on the aileron chord. For the 0.18c ailerons the gain in aileron effectiveness due to sealing the gap at the hinge axis was of the order of one-fifth and for the 0.09c ailerons the gain was about one-third. The importance of sealing the gap was demonstrated by the fact that the 0.09c ailerons with a slight increase in deflection range were made as effective as the 0.18c ailerons with an unsealed gap but required only about one-third as large an operating force.

Soule, H A↗

NASA NTRS2001

AST Composite Wing Program: Executive Summary

The Boeing Company demonstrated the application of stitched/resin infused (S/RFI) composite materials on commercial transport aircraft primary wing structures under the Advanced Subsonic technology (AST) Composite Wing contract. This report describes a weight trade study utilizing a wing torque box design applicable to a 220-passenger commercial aircraft and was used to verify the weight savings a S/RFI structure would offer compared to an identical aluminum wing box design. This trade study was performed in the AST Composite Wing program, and the overall weight savings are reported. Previous program work involved the design of a S/RFI-base-line wing box structural test component and its associated testing hardware. This detail structural design effort which is known as the "semi-span" in this report, was completed under a previous NASA contract. The full-scale wing design was based on a configuration for a MD-90-40X airplane, and the objective of this structural test component was to demonstrate the maturity of the S/RFI technology through the evaluation of a full-scale wing box/fuselage section structural test. However, scope reductions of the AST Composite Wing Program pre-vented the fabrication and evaluation of this wing box structure. Results obtained from the weight trade study, the full-scale test component design effort, fabrication, design development testing, and full-scale testing of the semi-span wing box are reported.

Karal, Michael↗

NASA NTRS1947

Wind-Tunnel Tests of a 1/8-Scale Powered Model of the XTB3F-1 Airplane, TED No. NACA 2382

A 1/8 scale model of the Grumman XTB3F-1 airplane was tested in the Langley 7- by 10-foot tunnel to determine the stability and control characteristics and to provide data for estimating the airplane handling qualities. The report includes longitudinal and lateral stability and control characteristics of the complete model, the characteristics of the isolated horizontal tail, the effects of various flow conditions through the jet duct, tests with external stores attached to the underside of the wing, ana tests simulating landing and take-off conditions with a ground board. The handling characteristics of the airplane have not been computed but some conclusions were indicated by the data. An improvement in the longitudinal stability was obtained by tilting the thrust line down. It is shown that if the wing flap is spring loaded so that the flap deflection varies with airspeed, the airplanes will be less stable than with the flap retracted or fully deflected. An increase in size of the vertical tail and of the dorsal fin gave more desirable yawing-moment characteristics than the original vertical tail and dorsal fin. Preventing air flow through the jet duct system or simulating jet operation with unheated air produced only small changes in the model characteristics. The external stores on the underside of the wing had only small effects on the model characteristics. After completion of the investigation, the model was returned to the contractor for modifications indicated by the test results.

McKee, John W.↗

NASA NTRS1987

An assessment of upper surface blowing for the reduction of tilt rotor download

A study evaluating the use of upper-surface blowing to reduce the wing download on a V-22 tilt rotor aircraft has been completed. The study assesses the penalties associated with the upper-surface blowing system (compressor weight, compressor power, etc.), and the reduction in wing download, for a wide range of blowing slot heights and blowing pressure ratios. Three wing configurations were investigated: blowing at both leading and trailing edges with no change in wing planform relative to the V-22 tilt rotor aircraft, blowing at both leading and trailing edges with a 25% reduction in wing chord, and blowing at the leading edge only with the flap deflected 75 deg. Predicted download is presented for all of these configurations, and is compared with the download of the baseline V-22 tilt rotor aircraft configuration. The optimum configuration had 15% less net download than the baseline V-22 configuration.

Faye, Robert E.↗

NASA NTRS1993

Design for cyclic loading endurance of composites

The application of the computer code IPACS (Integrated Probabilistic Assessment of Composite Structures) to aircraft wing type structures is described. The code performs a complete probabilistic analysis for composites taking into account the uncertainties in geometry, boundary conditions, material properties, laminate lay-ups, and loads. Results of the analysis are presented in terms of cumulative distribution functions (CDF) and probability density function (PDF) of the fatigue life of a wing type composite structure under different hygrothermal environments subjected to the random pressure. The sensitivity of the fatigue life to a number of critical structural/material variables is also computed from the analysis.

Shiao, Michael C.↗

NASA NTRS1985

Detailed pressure distribution measurements obtained on several configurations of an aspect-ratio-7 variable twist wing

Detailed pressure distribution measurements were made for 11 twist configurations of a unique, multisegmented wing model having an aspect ratio of 7 and a taper ratio of 1. These configurations encompassed span loads ranging from that of an untwisted wing to simple flapped wings both with and without upper-surface spoilers attached. For each of the wing twist configurations, electronic scanning pressure transducers were used to obtain 580 surface pressure measurements over the wing in about 0.1 sec. Integrated pressure distribution measurements compared favorably with force-balance measurements of lift on the model when the model centerbody lift was included. Complete plots and tabulations of the pressure distribution data for each wing twist configuration are provided.

Holbrook, G. T.↗

NASA NTRS1978

User's manual: Subsonic/supersonic advanced panel pilot code

Sufficient instructions for running the subsonic/supersonic advanced panel pilot code were developed. This software was developed as a vehicle for numerical experimentation and it should not be construed to represent a finished production program. The pilot code is based on a higher order panel method using linearly varying source and quadratically varying doublet distributions for computing both linearized supersonic and subsonic flow over arbitrary wings and bodies. This user's manual contains complete input and output descriptions. A brief description of the method is given as well as practical instructions for proper configurations modeling. Computed results are also included to demonstrate some of the capabilities of the pilot code. The computer program is written in FORTRAN IV for the SCOPE 3.4.4 operations system of the Ames CDC 7600 computer. The program uses overlay structure and thirteen disk files, and it requires approximately 132000 (Octal) central memory words.

Moran, J.↗