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At least 163 records · Page 9

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NASA NTRS1975

Summary of information on low-speed lateral-directional derivatives due to rate of change of sideslip beta prime

The results presented show that the magnitudes of the aerodynamic stability derivatives due to rate of change of sideslip become quite large at high angles of attack for swept- and delta-wing configurations, and that such derivatives have large effects on the calculated dynamic stability of these configurations at high angles of attack. The wind-tunnel test techniques used to measure the beta prime derivatives and various approaches used to predict them are discussed. Both the conventional oscillating-airfoil theory and the lag-of-the-sidewash theory are shown to be inadequate for predicting the vertical-tail contribution to the acceleration-in-sideslip derivative; a flow-field-lag theory, which is discussed, appears to give qualitative agreement with experimental data for a current twin-jet fighter configuration.

Coe, P. L., Jr.↗

NASA NTRS1975

Design aspects of zeppelin operations from case histories

Some widely held beliefs concerning the practicability of rigid airships in air carrier operations are discussed. It is shown by a review of past operational experience, and some basic aerostatic theory, their actual record and the reasons for their demise. Problems of atmospheric density and temperature variations, meteorological factors, aerodynamic stability and control, and mooring difficulties are discussed and related to actual case histories. Structural and flight efficiencies are compared to airplane efficiencies for airplanes contemporary with the zeppelin as well as modern designs. The difficulty of supporting new, commercial airship developments on an economic basis is made clear.

Maiersperger, W. P.↗

NASA NTRS1976

Summary of flight tests to determine the spin and controllability characteristics of a remotely piloted, large-scale (3/8) fighter airplane model

An unpowered, large, dynamically scaled airplane model was test flown by remote pilot to investigate the stability and controllability of the configuration at high angles of attack. The configuration proved to be departure/spin resistant; however, spins were obtained by using techniques developed on a flight support simulator. Spin modes at high and medium high angles of attack were identified, and recovery techniques were investigated. A flight support simulation of the airplane model mechanized with low speed wind tunnel data over an angle of attack range of + or - 90 deg. and an angle of sideslip range of + or - 40 deg. provided insight into the effects of altitude, stability, aerodynamic damping, and the operation of the augmented flight control system on spins. Aerodynamic derivatives determined from flight maneuvers were used to correlate model controllability with two proposed departure/spin design criteria.

Holleman, E. C.↗

NASA NTRS1976

Transonic lateral and longitudinal control characteristics of an F-8 airplane model equipped with an oblique wing

The aerodynamic stability and control characteristics of a 0.087-scale model of an F-8 airplane fitted with an oblique wing was studied. The wing had an elliptical planform (axis ratio = 8:1), a maximum thickness of 12 percent, and was tested at three sweep angles, 0, 45, and 60 deg. Six-component force and moment data were measured at zero sideslip for angles of attack between -6 and +16 deg, with the left and right ailerons deflected one at a time at angles between -14 deg and +14. Further tests were made with the horizontal tail deflected -5 and +2.5 deg. Test Mach numbers ranged from 0.6 to 1.4 at a Reynolds number of 20 million/m.

Smith, R. C.↗

NASA NTRS1976

Redundancy of hydraulic flight control actuators

The constraint of requiring airplanes to have inherent aerodynamic stability can be removed by using active control systems. The resulting airplane requires control system reliability approaching that of the basic airframe. Redundant control actuators can be used to achieve the required reliability, but create mechanization and operational problems. Of numerous candidate systems, two different approaches to solving the problems associated with redundant actuators which appear the most likely to be used in advanced airplane control systems are described.

Chenoweth, C. C.↗

NASA NTRS1976

Flight test design for efficient extraction of aircraft parameters

This paper considers the design of flight control inputs which result in a minimization of the nonuniqueness problem of parameter identification due to statistical correlation. The performance index for the control design is taken as a linear weighted sum of the squares of the correlation coefficients of the aerodynamic stability and control derivatives as computed from the Cramer-Rao lower bound matrix. An optimal input design is demonstrated for an F-8 aircraft with supercritical wing. Reduced correlations are noted and corresponding estimates and confidence levels presented.

Wells, W. R.↗

NASA NTRS1976

Results of wind tunnel RCS interaction tests on a 0.010-scale space shuttle orbiter model (51-0) in the Calspan Corporation 48-inch hypersonic shock tunnel (test 0A93)

A hypersonic shock tunnel test on a 0.010 scale SSV orbital configuration was performed to determine the effects of RCS jet/flow field interactions on SSV aerodynamic stability and control characteristics at various hypersonic Mach and Reynolds numbers. Flow field interaction data were obtained using pitch and roll jets. In addition, direct impingement data were obtained at a Mach number of zero with the test section pumped down to below 10 microns of mercury pressure.

Daileda, J. J.↗

NASA NTRS1978

Some unsteady separation problems for slender bodies

The unsteady Kutta-Joukowski condition, dynamic stall on oscillating airfoils, and unsteady shock wave-boundary layer interaction are discussed. Emphasis is placed on developing reliable prediction techniques and suppression of unsteady separation on oscillating control surfaces, wings, and rotating blades to improve aerodynamic stability.

Mccroskey, W. J.↗

NASA NTRS1979

Effects of fuselage forebody geometry on low-speed lateral-directional characteristics of twin-tail fighter model at high angles of attack

Low-speed, static wind-tunnel tests were conducted to explore the effects of fighter fuselage forebody geometry on lateral-directional characteristics at high angles of attack and to provide data for general design procedures. Effects of eight different forebody configurations and several add-on devices (e.g., nose strakes, boundary-layer trip wires, and nose booms) were investigated. Tests showed that forebody design features such as fineness ratio, cross-sectional shape, and add-on devices can have a significant influence on both lateral-directional and longitudinal aerodynamic stability. Several of the forebodies produced both lateral-directional symmetry and strong favorable changes in lateral-directional stability. However, the same results also indicated that such forebody designs can produce significant reductions in longitudinal stability near maximum lift and can significantly change the influence of other configuration variables. The addition of devices to highly tailored forebody designs also can significantly degrade the stability improvements provided by the clean forebody.

Carr, P. C.↗

NASA NTRS1980

Supersonic Cruise Research 1979, part 1

Aerodynamics, stability and control, propulsion, and environmental factors of the supersonic cruise aircraft are discussed. Other topics include airframe structures and materials, systems integration, and economics.

Source record↗

NASA NTRS1982

High angle-of-attack characteristics of a forward-swept wing fighter configuration

The NASA-Langley Research Center is currently investigating the high angle-of-attack characteristics of a forward-swept wing fighter technology demonstrator in a cooperative program with the Defense Advanced Research Projects Agency. The program includes static and dynamic wind-tunnel force tests, free-flight model tests, spin-tunnel tests, and piloted simulation. Particular emphasis is placed on identifying the contributions of the forward-swept wing to the configuration aerodynamics at high angles of attack. Results are presented to illustrate the wing contributions in terms of aerodynamic stability, flow visualization, and observation of free-flight characteristics.

Grafton, S. B.↗

NASA NTRS1983

Tethers open new space options

Several examples of possible applications of the tethering concept in space are examined. In particular, attention is given to a practical design of a 500-kg satellite system to be tethered at a distance of 100 km from the Space Shuttle. The satellite body has the form of a sphere, aerodynamically stabilized and fitted with a dockline adapter that mates with a capture mechanism at the tip of an extendable boom; the tether is a very flexible synthetic line 1-2 mm in diameter. Other applications include a wholly passive stable platform created by tethering two rows of empty Shuttle External Tanks or similar masses 10-20 km apart, a remote docking port for a space station, and constellations of space objects, with tethers used to tie them together and constrain their relative motions.

Bekey, I.↗

NASA NTRS1985

Flight characteristics of the AD-1 oblique-wing research aircraft

The AD-1 is a low-speed oblique-wing research airplane. This report reviews the vehicle's basic flight characteristics, including many aerodynamic, stability, and control effects that are unique to an oblique-wing configuration. These effects include the change in sideforce with angle of attack, moment changes with angle of attack and load factor, initial stall on the trailing wing, and inertial coupling caused by a roll-pitch cross product of inertia. An assessment of the handling qualities includes pilot ratings and comments. Ratings were generally satisfactory through 30 deg of wing sweep but degraded with increased sweep. A piloted simulation study indicated that a basic rate feedback control system could be used to improve the handling qualities at higher wing sweeps.

Sim, Alex G.↗

NASA NTRS1987

The interference of the model support mast with measurements of the longitudinal and lateral aerodynamic coefficients

The effects the single-bottom support masts used in the ONERA S1 and S4 wind tunnels have on aerodynamic data collected with scale model aircraft were examined experimentally and analytically. Systematic studies were performed on the flow characteristics around different diameters for the mounts. Scaling methods used to make data from one wind tunnel correspond to data from the other are described. Airbus 320 models were introduced into the tests and mast-body flow interactions were observed. A summary is presented of restrictions on the mast diameters, relative to cylindrical model diameters, which will minimize the effects the masts have on longitudinal and lateral aerodynamic stability data.

Vandekreeke, C.↗

NASA NTRS1987

A survey of aerobraking orbital transfer vehicle design concepts

The five existing design concepts of the aerobraking orbital transfer vehicle (namely, the raked sphere-cone designs, conical lifting-brake, raked elliptic-cone, lifting-body, and ballute) are reviewed and critiqued. Historical backgrounds, and the geometrical, aerothermal, and operational features of these designs are reviewed first. Then, the technological requirements for the vehicle (namely, navigation, aerodynamic stability and control, afterbody flow impingement, nonequilibrium radiation, convective heat-transfer rates, mission abort and multiple atmospheric passes, transportation and construction, and the payload-to-vehicle weight requirements) are delineated by summarizing the recent advancements made on these issues. Each of the five designs are critiqued and rated on these issues. The highest and the lowest ratings are given to the raked sphere-cone and the ballute design, respectively.

Park, Chul↗

NASA NTRS1988

Building a 1903 Wright 'Flyer' - By committee

This is a summary of a progress report of the Los Angeles AIAA Section Wright Flyer Project. Begun in late 1978, the project is devoted chiefly to construction of two replicas of the 1903 Wright 'Flyer'. The first, now being covered, is an exact replica intended for full-scale wind tunnel tests. The second will be a flying replica, incorporating minimal modifications to produce a less unstable aircraft. Considerable attention has been given to the aerodynamics, stability, and control of the 1903 'Flyer'. Wind-tunnel tests have been conducted with a 1/6 flexible model, and a 1/8 scale steel model tested at full-scale Reynolds numbers. The data have provided the basis for analyzing both the closed-loop and open-loop performance of the aircraft. Consideration is also given to aeronautical history both before and after 1903, to provide a better appreciation for the Wrights' achievements and a clearer perspective of their work in the context of aeronautical progress.

Culick, F. E. C.↗

NASA NTRS1988

The Horizon: A blended wing aircraft configuration design project, volume 3

The results of a study to design a High-Speed Civilian Transport (HSCT) using the blended wing-body configuration are presented. The HSCT is a Mach 2 to 5 transport aircraft designed to compete with current commercial aircraft. The subjects discussed are sizing, configuration, aerodynamics, stability and control, propulsion, performance, structures and pollution effects.

Keidel, Paul↗

NASA NTRS1989

Mars Rover Sample Return aerocapture configuration design and packaging constraints

This paper discusses the aerodynamics requirements, volume and mass constraints that lead to a biconic aeroshell vehicle design that protects the Mars Rover Sample Return (MRSR) mission elements from launch to Mars landing. The aerodynamic requirements for Mars aerocapture and entry and packaging constraints for the MRSR elements result in a symmetric biconic aeroshell that develops a L/D of 1.0 at 27.0 deg angle of attack. A significant problem in the study is obtaining a cg that provides adequate aerodynamic stability and performance within the mission imposed constraints. Packaging methods that relieve the cg problems include forward placement of aeroshell propellant tanks and incorporating aeroshell structure as lander structure. The MRSR missions developed during the pre-phase A study are discussed with dimensional and mass data included. Further study is needed for some missions to minimize MRSR element volume so that launch mass constraints can be met.

Lawson, Shelby J.↗