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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1947

Wing plan forms for high-speed flight

It is pointed out that, in the case of an airfoil of infinite aspect ratio moving at an angle of sideslip, the pressure distribution is determined solely by that component of the motion in a direction normal to the leading edge. It follows that the attachment of plane waves to the airfoil at near-sonic or supersonic speeds (Ackeret theory) may be avoided and the pressure drag may be reduced by the use of plan forms in which the angle of sweepback is greater than the Mach angle. The analysis indicates that for aerodynamic efficiency, wings designed for flight at supersonic speeds should be swept back at an angle greater than the Mach angle, and the angle of sweepback should be such that the component of velocity normal to the leading edge is less than the critical speed of the airfoil sections. This principle may also be applied to wings designed for subsonic speeds near the speed of sound, for which the induced velocities resulting from the thickness might otherwise be sufficiently great to cause shock waves.

Jones, Robert J↗
NASA NTRS1983

Exploratory low-speed wind-tunnel investigation of advanced commuter configurations including an over-the-wing propeller design

A recent low-speed wind-tunnel investigation of a three-surface regional transport configuration has shown large favorable power effects on longitudinal and lateral stability and marginal engine-out trim characteristics for some aft engine and empennage configurations. The present paper discusses these results in terms of static force test information obtained for power-off and power-on conditions. Also discussed in this paper are wind-tunnel results which indicate that mounting propellers over the wing can introduce large favorable slipstream interference effects which significantly reduce the wing drag at climb power conditions.

Johnson, J. L., Jr.↗
NASA NTRS2002

Multirate Flutter Suppression System Design for the Benchmark Active Controls Technology Wing: Theory and Design Procedure - Part 1

To study the effectiveness of various control system design methodologies, the NASA Langley Research Center initiated the Benchmark Active Controls Project. In this project, the various methodologies were applied to design a flutter suppression system for the Benchmark Active Controls Technology (BACT) Wing. This report describes a project at the University of Washington to design a multirate suppression system for the BACT wing. The objective of the project was two fold. First, to develop a methodology for designing robust multirate compensators, and second, to demonstrate the methodology by applying it to the design of a multirate flutter suppression system for the BACT wing.

Mason, Gregory S.↗
NASA NTRS2006

Impact of Aerodynamics and Structures Technology on Heavy Lift Tiltrotors

Rotor performance and aeroelastic stability are presented for a 124,000-lb Large Civil Tilt Rotor (LCTR) design. It was designed to carry 120 passengers for 1200 nm, with performance of 350 knots at 30,000 ft altitude. Design features include a low-mounted wing and hingeless rotors, with a very low cruise tip speed of 350 ft/sec. The rotor and wing design processes are described, including rotor optimization methods and wing/rotor aeroelastic stability analyses. New rotor airfoils were designed specifically for the LCTR; the resulting performance improvements are compared to current technology airfoils. Twist, taper and precone optimization are presented, along with the effects of blade flexibility on performance. A new wing airfoil was designed and a composite structure was developed to meet the wing load requirements for certification. Predictions of aeroelastic stability are presented for the optimized rotor and wing, along with summaries of the effects of rotor design parameters on stability.

Acree, C. W., Jr.↗
NASA NTRS1974

Transonic transport wings - Oblique or swept

A comparative evaluation of fixed-geometry and variable-sweep wing designs, a fixed delta wing, and oblique wings with a single body or two bodies suggests that an oblique wing is preferable in a transonic transport aircraft in terms of gross weight, fuel consumption, and aircraft noise, and also shows an acceptable aeroelastic stability. Further studies are, however, needed to develop the full potential of the oblique-wing concept, including its economic implications.

Jones, R. T.↗
NASA NTRS1988

Design, testing, and damage tolerance study of bonded stiffened composite wing cover panels

Results are presented from the application of damage tolerance criteria for composite panels to multistringer composite wing cover panels developed under NASA's Composite Transport Wing Technology Development contract. This conceptual wing design integrated aeroelastic stiffness constraints with an enhanced damage tolerance material system, in order to yield optimized producibility and structural performance. Damage tolerance was demonstrated in a test program using full-sized cover panel subcomponents; panel skins were impacted at midbay between stiffeners, directly over a stiffener, and over the stiffener flange edge. None of the impacts produced visible damage. NASTRAN analyses were performed to simulate NDI-detected invisible damage.

Madan, Ram C.↗
NASA NTRS1990

Conceptual design optimization study

The feasibility of applying multilevel functional decomposition and optimization techniques to conceptual design of advanced fighter aircraft was investigated. Applying the functional decomposition techniques to the conceptual design phase appears to be feasible. The initial implementation of the modified design process will optimize wing design variables. A hybrid approach, combining functional decomposition techniques for generation of aerodynamic and mass properties linear sensitivity derivatives with existing techniques for sizing mission performance and optimization, is proposed.

Hollowell, S. J.↗
NASA NTRS1989

Structural development of laminar flow control aircraft chordwise wing joint designs

For laminar flow to be achieved, any protuberances on the surface must be small enough to avoid transition to turbulent flow. However, the surface must have joints between the structural components to allow assembly or replacement of damaged parts, although large continuous surfaces can be utilized to minimize the number the number of joints. Aircraft structural joints usually have many countersunk bolts or rivets on the outer surface. To maintain no mismatch on outer surfaces, it is desirable to attach the components from the inner surface. It is also desirable for the panels to be interchangeable, without the need for shims at the joint, to avoid surface discontinuities that could cause turbulence. Fabricating components while pressing their outer surfaces against an accurate mold helps to ensure surface smoothness and continuity at joints. These items were considered in evaluating the advantages and disadvantages of the joint design concepts. After evaluating six design concepts, two of the leading candidates were fabricated and tested using many small test panels. One joint concept was also built and tested using large panels. The small and large test panel deflections for the leading candidate designs at load factors up to +1.5 g's were well within the step and waviness requirements for avoiding transition.The small panels were designed and tested for compression and tension at -65 F, at ambient conditions, and at 160 F. The small panel results for the three-rib and the sliding-joint concepts indicated that they were both acceptable. The three-rib concept, with tapered splice plates, was considered to be the most practical. A modified three-rib joint that combined the best attributes of previous candidates was designed, developed, and tested. This improved joint met all of the structural strength, surface smoothness, and waviness criteria for laminar flow control (LFC). The design eliminated all disadvantages of the initial three-rib concept except for unavoidable eccentricity, which was reduced and reacted satisfactorily by the rib supports. It should also result in a relatively simple low-cost installation, and makes it easy to replace any panels damaged in the field.

Fischler, J. E.↗
NASA NTRS1992

HSCT design for reduced sonic boom

The topics covered include the following: low sonic boom design perspective; design approach for reduced sonic boom; target sonic boom waveforms; airplane design for reduced sonic boom loudness; design procedure for low sonic boom; wing design and nacelle lift effects; area distributions and F-functions due to volume; fuselage area distributions; low sonic boom design, configuration 3B; sonic boom characteristics; sizing, performance, and noise characteristics; a summary of phase 3 configurations; impact of sonic boom design constraints; and wing loading considerations.

Haglund, George T.↗
NASA NTRS1980

Results of design studies and wind tunnel tests of high-aspect-ratio supercritical wings for an energy efficient transport

These basic characteristics of critical wings included wing area, aspect ratio, average thickness, and sweep as well as practical constraints on the planform and thickness near the wing root to allow for the landing gear. Within these constraints, a large matrix of wing designs was studied with spanwise variations in the types of airfoils and distribution of lift as well as some small planform changes. The criteria by which the five candidate wings were chosen for testing were the cruise and buffet characteristics in the transonic regime and the compatibility of the design with low speed (high-lift) requirements. Five wing-wide-body configurations were tested in the NASA Ames 11-foot transonic wind tunnel. Nacelles and pylons, flap support fairings, tail surfaces, and an outboard aileron were also tested on selected configurations.

Steckel, D. K.↗
NASA NTRS1990

Transonic wind tunnel test of a 14 percent thick oblique wing

An experimental investigation was conducted at the ARC 11- by 11-Foot Transonic Wind Tunnel as part of the Oblique Wing Research Aircraft Program to study the aerodynamic performance and stability characteristics of a 0.087-scale model of an F-8 airplane fitted with an oblique wing designed by Rockwell International. The 10.3 aspect ratio, straight-tapered wing of 0.14 thickness/chord ratio was tested at two different mounting heights above the fuselage. Additional tests were conducted to assess low-speed behavior with and without flaps, aileron effectiveness at representative flight conditions, and transonic drag divergence with 0 degree wing sweep. Longitudinal stability data were obtained at sweep angles of 0, 30, 45, 60, and 65 degrees, at Mach numbers ranging from 0.25 to 1.40. Test Reynolds numbers varied from 3.2 to 6.6 x 10 exp 6/ft. and angle of attack ranged from -5 to +18 degrees. Most data were taken at zero sideslip, but a few runs were at sideslip angles of +/- 5 degrees. The raised wing position proved detrimental overall, although side force and yawing moment were reduced at some conditions. Maximum lift coefficient with the flaps deflected was found to fall short of the value predicted in the preliminary design document. The performance and trim characteristics of the present wing are generally inferior to those obtained for a previously tested wing designed at ARC.

Kennelly, Robert A., Jr.↗
NASA NTRS1978

Computational wing optimization and wind tunnel test of semi-span model

A computational transonic wing design procedure has been developed and verified by a wind tunnel test of a variable camber semi-span wing model. The Bailey-Ballhaus transonic potential flow analysis code linked to Vanderplaat's constrained minimization routine was used to optimize test configurations at 0.9 Mach number. Based on wind tunnel test results, computationally optimized designs were as efficient as the best configurations determined by previous parametric testing and performed better at off-design points. Wind tunnel wing pressures agreed well with predictions from the improved Bailey-Ballhaus code at moderate CL's. Computational optimization was shown to be an effective transonic wing design tool.

Haney, H. P.↗
NASA NTRS1990

Design of a high speed business transport

The design of a High Speed Business Transport (HSBT) was considered by the Aeronautical Design Class during the academic year 1989 to 1990. The project was chosen to offer an opportunity to develop user friendliness for some computer codes such as WAVE DRAG, supplied by NASA/Langley, and to experiment with several design lessons developed by Dr. John McMasters and his colleages at Boeing. Central to these design lessons was an appeal to marketing and feasibility considerations. There was an emphasis upon simplified analytical techniques to study trades and to stimulate creative thinking before committing to extensive analytical activity. Two designs stood out among all the rest because of the depth of thought and consideration of alternatives. One design, the Aurora, used a fixed wing design to satisfy the design mission: the Viero used a swept wing configuration to overcome problems related to supersonic flight. A summary of each of these two designs is given.

Source record↗
NASA NTRS1999

Analysis and Inverse Design of the HSR Arrow Wing Configuration with Fuselage, Wing, and Flow Through Nacelles

The design process for developing the natural flow wing design on the HSR arrow wing configuration utilized several design tools and analysis methods. Initial fuselage/wing designs were generated with inviscid analysis and optimization methods in conjunction with the natural flow wing design philosophy. A number of designs were generated, satisfying different system constraints. Of the three natural flow wing designs developed, the NFWAc2 configuration is the design which satisfies the constraints utilized by McDonnell Douglas Aerospace (MDA) in developing a series of optimized configurations; a wind tunnel model of the MDA designed OPT5 configuration was constructed and tested. The present paper is concerned with the viscous analysis and inverse design of the arrow wing configurations, including the effects of the installed diverters/nacelles. Analyses were conducted with OVERFLOW, a Navier-Stokes flow solver for overset grids. Inverse designs were conducted with OVERDISC, which couples OVERFLOW with the CDISC inverse design method. An initial system of overset grids was generated for the OPT5 configuration with installed diverters/nacelles. An automated regridding process was then developed to use the OPT5 component grids to create grids for the natural flow wing designs. The inverse design process was initiated using the NFWAc2 configuration as a starting point, eventually culminating in the NFWAc4 design-for which a wind tunnel model was constructed. Due to the time constraints on the design effort, initial analyses and designs were conducted with a fairly coarse grid; subsequent analyses have been conducted on a refined system of grids. Comparisons of the computational results to experiment are provided at the end of this paper.

Krist, Steven E.↗
NASA NTRS1978

Drones for aerodynamic and structural testing /DAST/ - A status report

A program for providing research data on aerodynamic loads and active control systems on wings with supercritical airfoils in the transonic speed range is described. Analytical development, wind tunnel tests, and flight tests are included. A Firebee II target drone vehicle has been modified for use as a flight test facility. The program currently includes flight experiments on two aeroelastic research wings. The primary purpose of the first flight experiment is to demonstrate an active control system for flutter suppression on a transport-type wing. Design and fabrication of the wing are complete and after installing research instrumentation and the flutter suppression system, flight testing is expected to begin in early 1979. The experiment on the second research wing - a fuel-conservative transport type - is to demonstrate multiple active control systems including flutter suppression, maneuver load alleviation, gust load alleviation, and reduce static stability. Of special importance for this second experiment is the development and validation of integrated design methods which include the benefits of active controls in the structural design.

Murrow, H. N.↗