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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1955

Lateral Stability and Control Measurements of a 0.0858-Scale Model of the Lockheed XF-104 Airplane at Transonic Speeds

An investigation of the lateral stability and control effectiveness of a 0.0858-scale model of the Lockheed XF-104 airplane has been conducted in the Langley 16-foot transonic tunnel. The model has a low aspect ratio, 3.4-percent-thick wing with negative dihedral. The horizontal tail is located on top of the vertical tail. The investigation was made through a Mach number range of 0.80 to 1.06 at sideslip angles of -5 deg. to 5 deg. and angles of attack from 0 deg. to 16 deg. The control effectiveness of the aileron, rudder, and yaw damper were determined through the Mach number and angle-of-attack range. The results of the investigation indicated that the directional stability derivative was stable and that positive effective dihedral existed throughout the lift-coefficient range and Mach number range tested. The total aileron effectiveness, which in general produced favorable yaw with rolling moment, remained fairly constant for lift coefficients up to about 0.8 for the Mach number range tested. Yawing-moment effectiveness of the rudder changed little through the Mach number range. However, the yaw damper effectiveness decreased about 30 percent at the intermediate test Mach numbers.

Arabian, Donald D.↗
NASA NTRS1953

Charts and approximate formulas for the estimation of aeroelastic effects of the lateral control of swept and unswept wings

Charts and approximate formulas are presented for the estimation of static aeroelastic effects on the spanwise lift distribution, rolling-moment coefficient, and rate of roll due to the deflection of ailerons on swept and unswept wings at subsonic and supersonic speeds. Some design considerations brought out by the results of this report are discussed. This report treats the lateral-control case in a manner similar to that employed in NACA Report 1140 for the symmetric-flight case, and is intended to be used in conjunction with NACA Report 1140 and the charts and formulas presented therein.

Foss, Kenneth A↗
NASA NTRS2000

Flight Control Using Distributed Shape-Change Effector Arrays

Recent discoveries in material science and fluidics have been used to create a variety of novel effector devices that offer great potential to enable new approaches to aerospace vehicle flight control. Examples include small inflatable blisters, shape-memory alloy diaphragms, and piezoelectric patches that may be used to produce distortions or bumps on the surface of an airfoil to generate control moments. Small jets have also been used to produce a virtual shape-change through fluidic means by creating a recirculation bubble on the surface of an airfoil. An advanced aerospace vehicle might use distributed arrays of hundreds of such devices to generate moments for stabilization and maneuver control, either augmenting or replacing conventional ailerons, flaps or rudders. This research demonstrates the design and use of shape-change device arrays for a tailless aircraft in a low-rate maneuvering application. A methodology for assessing the control authority of the device arrays is described, and a suite of arrays is used in a dynamic simulation to illustrate allocation and deployment methodologies. Although the authority of the preliminary shape-change array designs studied in this paper appeared quite low, the simulation results indicate that the effector suite possessed sufficient authority to stabilize and maneuver the vehicle in mild turbulence.

Raney, David L.↗
NASA NTRS1929

:Theoretical investigation of the effect of the ailerons on the wing of an airplane

The present work investigates, on the basis of Prandtl's wing theory, the form of the lift distribution when the ailerons are deflected in opposite directions. An ideal fluid and a wing with a rectangular form are assumed. The moments must not cause any rotation of the wing or any deviation from the rectilinear motion.

AILERONS - DISPLACEMENT↗
NASA NTRS1995

Feedback control laws for highly maneuverable aircraft

During this year, we concentrated our efforts on the design of controllers for lateral/directional control using mu synthesis. This proved to be a more difficult task than we anticipated and we are still working on the designs. In the lateral-directional control problem, the inputs are pilot lateral stick and pedal commands and the outputs are roll rate about the velocity vector and side slip angle. The control effectors are ailerons, rudder deflection, and directional thrust vectoring vane deflection which produces a yawing moment about the body axis. Our math model does not contain any provision for thrust vectoring of rolling moment. This has resulted in limitations of performance at high angles of attack. During 1994-95, the following tasks for the lateral-directional controllers were accomplished: (1) Designed both inner and outer loop dynamic inversion controllers. These controllers are implemented using accelerometer outputs rather than an a priori model of the vehicle aerodynamics; (2) Used classical techniques to design controllers for the system linearized by dynamics inversion. These controllers acted to control roll rate and Dutch roll response; (3) Implemented the inner loop dynamic inversion and classical controllers on the six DOF simulation; (4) Developed a lateral-directional control allocation scheme based on minimizing required control effort among the ailerons, rudder, and directional thrust vectoring; and (5) Developed mu outer loop controllers combined with classical inner loop controllers.

Garrard, William L.↗
NASA NTRS2009

Sensitivity Analysis of Linear Programming and Quadratic Programming Algorithms for Control Allocation

The Next Generation (NextGen) transport aircraft configurations being investigated as part of the NASA Aeronautics Subsonic Fixed Wing Project have more control surfaces, or control effectors, than existing transport aircraft configurations. Conventional flight control is achieved through two symmetric elevators, two antisymmetric ailerons, and a rudder. The five effectors, reduced to three command variables, produce moments along the three main axes of the aircraft and enable the pilot to control the attitude and flight path of the aircraft. The NextGen aircraft will have additional redundant control effectors to control the three moments, creating a situation where the aircraft is over-actuated and where a simple relationship does not exist anymore between the required effector deflections and the desired moments. NextGen flight controllers will incorporate control allocation algorithms to determine the optimal effector commands and attain the desired moments, taking into account the effector limits. Approaches to solving the problem using linear programming and quadratic programming algorithms have been proposed and tested. It is of great interest to understand their relative advantages and disadvantages and how design parameters may affect their properties. In this paper, we investigate the sensitivity of the effector commands with respect to the desired moments and show on some examples that the solutions provided using the l2 norm of quadratic programming are less sensitive than those using the l1 norm of linear programming.

Frost, Susan A.↗
NASA NTRS1976

High supersonic stability and control characteristics of a 0.015-scale (remotely controlled elevon) model 44-0 space shuttle orbiter tested in the NASA/LaRC 4-foot UPWT (LEG 2) (LA75), volume 1

Wind tunnel tests are reported on a 0.015-scale SSV orbiter model with remote independently operated left and right elevon surfaces. Special attention was directed to definition of nonlinear aerodynamic characteristics by taking data at small increments. Six component aerodynamic force and moment and elevon position data were recorded for the space shuttle orbiter with various elevon, aileron rudder and speed brake deflection combinations over an angle of attack range from -4 deg to 32 deg at angles of sideslip of 0 deg and 3 deg. Additional tests were made over an angle of sideslip range from -6 deg to 8 deg at selected angles of attack. Test Mach numbers were 2.86, 2.90, 3.90 and 4.60 with Reynolds numbers held at a constant 2.0 x 1 million per foot.

Ball, J. W.↗
NASA NTRS2016

Rotary Balance Wind Tunnel Testing for the FASER Flight Research Aircraft

Flight dynamics research was conducted to collect and analyze rotary balance wind tunnel test data in order to improve the aerodynamic simulation and modeling of a low-cost small unmanned aircraft called FASER (Free-flying Aircraft for Sub-scale Experimental Research). The impetus for using FASER was to provide risk and cost reduction for flight testing of more expensive aircraft and assist in the improvement of wind tunnel and flight test techniques, and control laws. The FASER research aircraft has the benefit of allowing wind tunnel and flight tests to be conducted on the same model, improving correlation between wind tunnel, flight, and simulation data. Prior wind tunnel tests include a static force and moment test, including power effects, and a roll and yaw damping forced oscillation test. Rotary balance testing allows for the calculation of aircraft rotary derivatives and the prediction of steady-state spins. The rotary balance wind tunnel test was conducted in the NASA Langley Research Center (LaRC) 20-Foot Vertical Spin Tunnel (VST). Rotary balance testing includes runs for a set of given angular rotation rates at a range of angles of attack and sideslip angles in order to fully characterize the aircraft rotary dynamics. Tests were performed at angles of attack from 0 to 50 degrees, sideslip angles of -5 to 10 degrees, and non-dimensional spin rates from -0.5 to 0.5. The effects of pro-spin elevator and rudder deflection and pro- and anti-spin elevator, rudder, and aileron deflection were examined. The data are presented to illustrate the functional dependence of the forces and moments on angle of attack, sideslip angle, and angular rate for the rotary contributions to the forces and moments. Further investigation is necessary to fully characterize the control effectors. The data were also used with a steady state spin prediction tool that did not predict an equilibrium spin mode.

Denham, Casey↗
NASA NTRS1943

The Effect of Mass Distribution on the Lateral Stability and Control Characteristics of an Airplane as Determined by Tests of a Model in the Free-Flight Tunnel

The effects of mass distribution on lateral stability and control characteristics of an airplane have been determined by flight tests of a model in the NACA free-flight tunnel. In the investigation, the rolling and yawing movements of inertia were increased from normal values to values up to five times normal. For each moment-of-inertia condition, combinations of dihedral and vertical-tail area representing a variety of airplane configurations were tested. The results of the flight tests of the model were correlated with calculated stability and control characteristics and, in general, good agreement was obtained. The tests showed the following effects of increased rolling and yawing moments of inertia: no appreciable change in spiral stability; reductions in oscillatory stability that were serious at high values of dihedral; a reduction in the sensitivity of the model to gust disturbances; and a reduction in rolling acceleration provided by the ailerons, which caused a marked increase in time to reach a given angle of bank. The general flight behavior of the model became worse with increasing moments of inertia but, with combinations of small effective dihedral and large vertical-tail area, satisfactory flight characteristics were obtained at all moment-of-inertia conditions.

STABILITY & CONTROL, LATERAL↗
NASA NTRS1979

Aerodynamic characteristics of the 140A/B space shuttle orbiter at Mach 10.3

A wind-tunnel investigation was conducted to determine the static longitudinal and lateral-directional characteristics of the 140/B space shuttle orbiter configurations. A 0.010-scale model was tested at angles of attack from 12 deg to 36.5 deg at Reynolds numbers ranging from 0.62 x to 1.33 x based on fuselage reference length. Stability, control, and performance characteristics were obtained for several deflections of the elevons and body flap. Effects of aileron deflection on roll control and longitudinal stability were also measured. The results indicate that the orbiter is neutrally stable at a 20 degs angle of attack with control deflections set at 0 degs and the center of gravity at 65 percent of fuselage length. For a typical entry attitude of 30 degs stable trim resulting in a lift-drag ratio of 1.40 is possible. Increasing the Reynolds number yielded higher values of lift-drag ratio, but only for angles of attack up to 24 degs. The orbiter is directionally unstable with positive dihedral effect. Aileron deflection resulted in adverse yaw to roll control and also caused negative increments in pitching moment over the test angle-of-attack range.

Bernot, P. T.↗
NASA NTRS1954

A Free-flight Wind Tunnel for Aerodynamic Testing at Hypersonic Speeds

The supersonic free-flight wind tunnel is a facility at the Ames Laboratory of the NACA in which aerodynamic test models are gun-launched at high speed and directed upstream through the test section of a supersonic wind tunnel. In this way, test Mach numbers up to 10 have been attained and indications are that still higher speeds will be realized. An advantage of this technique is that the air and model temperatures simulate those of flight through the atmosphere. Also the Reynolds numbers are high. Aerodynamic measurements are made from photographic observation of the model flight. Instruments and techniques have been developed for measuring the following aerodynamic properties: drag, initial lift-curve slope, initial pitching-moment-curve slope, center of pressure, skin friction, boundary-layer transition, damping in roll, and aileron effectiveness. (author)

Seiff, Alvin↗
NASA NTRS1992

Further wind tunnel investigation of the SM701 airfoil with aileron and turbulators

Wind tunnel tests were performed on a two-dimensional model of the SM701 airfoil designed for use on the World Class gliders. The test covered a range of Reynolds numbers from 500,000 to 1.7 million. Aerodynamic forces and moments were measured with an external balance. Momentum loss method measurements of the section drag coefficient were also made. Flow visualization techniques provided information on transition from laminar to turbulent flow. Lift, drag, and pitching moment were analyzed and comparisons were made with predicted and previously obtained experimental data. The effects of V-tape turbulators for use in turbulent drag reduction were studied. The performance of a 25 percent chord aileron deflected through plus or minus 20 degrees was researched. The model was designed, constructed, and tested by students at Texas A&M University.

Steen, Gregory↗
NASA NTRS1986

Subsonic aerodynamic characteristics of a circular body earth-to-orbit transport

To reduce the weight and improve the performance of future earth-to-orbit transports, the use of circular cross sections in the fuselage bodies of these vehicles is being considered at the Langley Research Center. Structurally, circular cross sections are stronger and lighter than other shapes. A study has been made applying the circular body concept to a vertical-takeoff, delta-winged, single-stage-to-orbit transport. A 52 in., 0.022-scale model of the circular body vehicle was tested at a Mach number of 0.3 in the 7 x 10 ft High Speed Wind Tunnel at the Langley Research Center to obtain aerodynamic forces and moments. Oil-flow photographs were taken at several angles of attack to aid in the aerodynamic analysis. Model control surfaces included elevons and ailerons for the evaluation of pitch and roll characteristics and either wing-tip fins, a nose mounted dorsal fin, or a conventional vertical tail for the evaluation of yaw characteristics. Other deflecting surfaces included speedbrakes and body flaps. Basic data on longitudinal flight characteristics are shown, including lift, drag, and pitching moments. Comparisons of the directional stability and control effectiveness of the three directional control devices are also shown.

Lepsch, R. A., Jr.↗
NASA NTRS1974

Effect of ELEVON gap configurations on the longitudinal stability and control effectiveness of the 43-0 space shuttle orbiter (OA118)

Experimental aerodynamic investigations were conducted on a stingmounted 0.0405-scale representation of the 140A/B space shuttle orbiter in a 7.75 by 11-Foot low speed wind tunnel from April 24 to April 26, 1974. Differential inboard/outboard elevon panel deflections with the 6-inch gap were investigated to determine outboard panel aileron effectiveness. The elevons were deflected from +20 degrees to -40 degrees in various combinations. Aerodynamic force and moment data for the orbiter were measured in the body axis system by an internally mounted, six-component strain gage balance. The model was sting mounted with the center of rotation located at F.S. 60.172. The angle of attack range was from -10 degrees to +24 degrees.

Hughes, T.↗