Systems-related criteria are used in evaluating several candidate approaches aimed at the reduction of land area needed to support a given HF transmitting communications requirement. The various design alternatives are (a) broadband antenna with tunable multicoupler, (b) broadband 6-30 MHz antenna with 2-6 MHz base tuner, (c) 2-4 and 4-8 MHz Moderate-Q antennas, and (d) 2-6 MHz tuned whip antenna. The tunable multicoupler is best suited for directional or high-angle antennas. The tuned antennas...
Topics: DTIC Archive, SYSTEMS EXPLORATION INC SAN DIEGO CA, *STATIONS, *BROADBAND ANTENNAS, *DIRECTIONAL...
The Nonlinear Progressive-wave Equation (NPE) model has been reformulated for wider propagation angle accuracy. The wide-angle NPE results from range-integrating the second-order time domain nonlinear wave equation rather than reducing it to a one-way equation as in the original NPE. The numerical implementation of the second-order NPE retains two time levels rather than one. The resulting model is referred to as NPE2. Benchmark tests reveal that root mean square (rms) errors in the model are...
Topics: DTIC Archive, McDonald, B. E., NAVAL RESEARCH LAB WASHINGTON DC ACOUSTICS SYSTEMS BRANCH,...
The control of flow over a multi-element wing has been investigated. At large incidence angles, the flow becomes fully separated. The wing geometry was considered critical to management of flow energy through organization of vorticity and controlling its shedding on the upper wing surface. A flat plate wing, with the planform of a F-15 wing, was reconfigured to accommodate the locked vortex. Spanwise blowing was used to initiate and/or increase the strength of the vortical flow. It was...
Topics: DTIC Archive, , A D, TENNESSEE UNIV TULLAHOMA, *VORTICES, *ANGLE OF ATTACK, *AERODYNAMICS,...
We present a class of electrowetting systems in which lipid bilayers function as reversibly wettable dielectrics, eliminating the need for solid organic dielectrics (e.g. fluoropolymers) in electrowetting systems. These bilayers form spontaneously between water drops and hafnium oxide surfaces in oil and can withstand high electric fields, enabling high contact angle changes at unprecedentedly low voltages. We demonstrate that under well-defined conditions, these electrowetting systems are...
Topics: DTIC Archive, MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB, *DIELECTRICS, CAPACITANCE, ELECTRIC...
A description is given of a simple adapter which was developed for use with the Norelco high-angle spectrometer with samples cooled to 78 deg K. The cryostat consists of a sample holder, an insulated open chamber for liquid N, and an insulated cover to prevent ice formation near the sample. The device was successfully used to investigate the transition in magnetite down to 78 deg K.
Topics: DTIC Archive, Calhoun, B. A., Abrahams, S. C., MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR...
A 2D framework for solving the sheath equations near a dielectric corner has been developed and applied in a quasi 2D fashion to solve for sheath thickness and potential profile. When appropriate, boundary conditions were taken from an HPHall model of an SPT-70 Hall thruster. Ion paths within the sheath were also calculated. Results suggest that the radial acceleration provided by the sheath has the ability to produce significant changes in ion trajectories. However, the changes seen in the...
Topics: DTIC Archive, CALIFORNIA INST OF TECH PASADENA, *HALL THRUSTERS, THICKNESS, EXPERIMENTAL DATA,...
The study of vortex breakdown over delta wings at high angles of attack (AOA) has been an interest to researchers, mathematicians, and aircraft designers for decades. It is a very hot topic as it relates to many aircraft being designed today and because no complete understanding exists. Most of the understanding that does exist comes in the form of the problems associated with vortex breakdown. Many question if it is possible to control the breakdown to avoid the problems and to aid the...
Topics: DTIC Archive, O'Dowd, Devin O., AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH, *VORTICES, *DELTA...
Modern qualitative theory of differential equations originated with the work of Poincare, who essentially had arrived at the phenomenon which is presently called Hopf bifurcation. Poincare's work was later developed by Androuov and Pontryagin and Hopf. More recently, experience with the aircraft at high angles of attack shows loss of stability for some critical values of parameter (e.g., angle of attack, or the velocity). This phenomenon was interpreted by Mehra et al. as the Hopf bifurcation;...
Topics: DTIC Archive, Baillieul,J, SCIENTIFIC SYSTEMS INC CAMBRIDGE MA, *Aircraft models,...
Accelerating flow around an airfoil was visualized using smoke techniques. The flow started from rest and acceleration was kept constant for 5 seconds. Movies and single-frame photographs of the developing flow were taken for various angles of attack. The developing vortex patterns are interpreted as the elaborate initiation of an unsteady turbulent vortex street. (Author)
Topics: DTIC Archive, Freymuth,P, COLORADO UNIV AT BOULDER DEPT OF AEROSPACE ENGINEERING SCIENCES,...
We consider the problem of designing stabilizing control laws for flight over a broad range of angles-of-attack which also serve to signal the pilot of impending stall. The paper employs bifurcation stabilization coupled with more traditional linear control system design. To focus the discussion, a detailed analysis is given for a model of the longitudinal dynamics of an F-8 Crusader.
Topics: DTIC Archive, Abed, Eyad H, MARYLAND UNIV COLLEGE PARK SYSTEMS RESEARCH CENTER, *FLIGHT CONTROL...
This paper uses concrete examples of calculations to analyze the reliability of C(sub n beta.dyn) as a stability criterion at high angles of attack, and makes deductions regarding the errors that may result from the use of this criterion. We obtain results that will be of value in the use of this criterion. Keywords: Stability at high angle of attack, Aeronautics derivatives, Chinese translations, China.
Topics: DTIC Archive, Zhidai, He, FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OH, *AERODYNAMIC STABILITY,...
A detailed% analysis of steadly autorotative vertical aescent of a helicopter is made, in which the effect of considering induced velocity constant over the disk is examined. The induced velocity is first considered constant, then variable over the disk; and the results are compared for a typical helicopter. Although considering the induced velocity constant over the disk causes considerable error in the load distribution along a blade, the revolutions per minute of the rotor and rate of...
Topics: DTIC Archive, Nikolsky, A A, PRINCETON UNIV NJ, *HELICOPTER ROTORS, *HELICOPTERS, *VERTICAL...
A set of aircraft maneuvers has been developed to augment evaluation maneuvers used currently by the flying qualities and flight test communities. These maneuvers extend evaluation to full aircraft dynamics throughout the aircraft flight envelope. As a result, a tie has been established between operational use and design parameters without losing control of the aircraft evaluation process. Twenty maneuvers are described as an initial set to examine primarily high-angle-of attack conditions....
Topics: DTIC Archive, Wilson, David J, MCDONNELL DOUGLAS AEROSPACE ST LOUIS MO, *FLIGHT ENVELOPE, *FLIGHT...
Cebeci's viscous/inviscid interaction program was applied to the analysis of steady, two dimensional, incompressible flow past four airfoils, the NACA 66 sub 3-018, 0010 (Modified), 4412 and the Wortmann FX 63-137. Detailed comparisons with the available experimental results show that the essential features are correctly modelled, but that significant discrepancies are found in regions of flow separations. Theses.
Topics: DTIC Archive, Mathre, John M, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *INCOMPRESSIBLE FLOW,...
Recent developments in post-stall maneuverability and thrust vectoring have opened up new possibilities in the field of air combat maneuvering. High angle of attack maneuvers like the Cobra, Herbst Reversal, and Chakra demonstrate that today's cutting edge fighters are capable of exploiting the post-stall flight regime for very dynamic and unconventional maneuvers. With the development and testing of Unmanned Combat Aerial Vehicles, even greater maneuvering ability is expected. However, little...
Topics: DTIC Archive, Carter, Benjamin R, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *AERIAL WARFARE, *FLIGHT...
Surface and near surface acoustic backscatter measurements at 108, 72, 36, and 18 kHz made off the coast of Fort Lauderdale, Florida, have been analyzed and the results are presented in this report. The measurements were made with bottom mounted equipment looking upward at the ocean surface; wind speeds encountered varied from about 2.5 to about 16 m/s. Vertical incidence acoustic measurements were used to evaluate near surface volume backscatter versus depth, which were then used to estimate...
Topics: DTIC Archive, Boehme, Hollis, TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS, *OCEAN SURFACE,...
The US Army Research Laboratory developed and deployed an acoustic mortar and rocket detection and locating device, in a little over two months. After receiving a direct request from Iraq, ARL merged components from a number of programs to enable the rapid fielding of this capability. As of mid 2004, four Unattended Transient Acoustic MASINT Systems (UTAMS) have been operated detecting mortar fire, rocket launches and IED's while displaying the localized results. Due to the typically high angle...
Topics: DTIC Archive, Tenney, Stephen, ARMY RESEARCH LAB ADELPHI MD, *ACOUSTIC DETECTION, *ACOUSTIC ARRAYS,...
Limit cycle oscillations (LCO) have been observed for elastic wings at moderate to high angles of attack where separated flow is thought to occur. At transonic flow conditions with shock waves present, flow separation may occur at moderate angles of attack. For higher angles of attack, separation may occur at (low) subsonic conditions. Empirical quasi steady aerodynamic models based on steady state experimental data have shown some success in predicting the observed LCO. New theoretical...
Topics: DTIC Archive, Dowell, Earl H., DUKE UNIV DURHAM NC, *AEROELASTICITY, *OSCILLATION, *FLOW...
This report is a theoretical study of various phenomena observed in the low subsonic regime when a slender cone of revolution is pitched to high angles of attack. Three-dimensional boundary layers are calculated up to the line of primary separation. The structure of the separated wake is obtained with a two-dimensional model and the results are used as input in a leeside boundary layer calculation. This calculation is carried on to the line of secondary separation. The positions of separation...
Topics: DTIC Archive, Botnan,Jan Ivar, NORWEGIAN DEFENCE RESEARCH ESTABLISHMENT KJELLER, *Subsonic flow,...
Sliding mode control is applied to the design of flight control systems capable of operating with limited bandwidth actuators and in the presence of significant damage to the airframe and/or control effector actuators. Although inherently robust, sliding mode control algorithms have been hampered by their sensitivity to the effects of parasitic unmodeled dynamics, such as those associated with actuators and structural modes. It is known that asymptotic observers can alleviate this sensitivity...
Topics: DTIC Archive, Wells, Scott R, CALIFORNIA UNIV DAVIS, *FLIGHT CONTROL SYSTEMS, *DYNAMICS, *SLIDING,...
In this paper the results of investigations will be presented which dealt with the determination of intake flows at high and very high angles of attack. The overall approach comprised of experimental and numerical(CFD) investigations will be detailed. Results and comparisons between flows at small and large angles of attack will be used to try to clarify the origin of possible disturbances in the intake flow. Intake bleed and the flow losses at the intake entrance are identified as major...
Topics: DTIC Archive, Bissinger, Norbert C., Jost, Michael, DAIMLER CHRYSLER AEROSPACE AG MUNICH (GERMANY),...
The experimental investigation of the effect of a winglet on the spatial vortex of a slender body at a high angle of attack is presented. This investigation clearly shows that the circulation of the body vortex is minimized by the winglet and the vortex position is lower than that without the winglet, so that the asymmetric problem can be solved.
Topics: DTIC Archive, Zixing,Wang, FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OH, *VORTICES, SPATIAL...
Computational and experimental methods have been used to systematically study one and two airfoils undergoing unsteady motion. First, a single airfoil analysis was done with the modified computer code, U2DIIF. Thrust, efficiency, and phase relationships were computed and compared to existing theoretical results. Furthermore, to help understand the dynamic stall process, relationships were developed between steady and quasi-steady pressure distributions for an airfoil undergoing a ramp motion....
Topics: DTIC Archive, Neace, Kerry S, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *PRESSURE GRADIENTS,...
This workshop promoted the exchange of information among researchers currently studying unsteady aerodynamics at high angle-of-attack and provided a basis for identification of the major, unresolved issues in this area. Detailed technical presentations were given covering AFOSR's 6.1 Trial in Unsteady Aerodynamics, namely Quasi-Two-Dimensional Unsteady Flows, Three-Dimensional Unsteady Flows and the Control of Unsteady Flows. High angle of attack, Unsteady flows.
Topics: DTIC Archive, Rockwell, Donald, LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND...
An estimated probability distribution of the backscatter is commonly used to determine the threshold for distinguishing targets from clutter at a given false alarm rate. Data collected at high grazing angles (15 deg - 45 deg) by the Defence Science Technology Organisation's Ingara fully polarimetric X-band radar demonstrates that the commonly used K-distribution is not always adequate for modelling the probability distribution. This is especially the case for the horizontal polarisation when...
Topics: DTIC Archive, DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION EDINBURGH (AUSTRALIA), *GRAZING ANGLES,...
The present paper covers two distinctly different subjects. The first subject is the efforts of the U.S. Navy and the U.S. Army to develop aerial torpedos during World War I. The Navy team had such prominent engineers as Elmer and Lawrence Sperry and Glenn Curtis. The Army team included Charles F. Kettering and Orville Wright. Despite these eminent personalities, a successful aerial torpedo was not developed for use in World War I. The second subject area covered in the paper is suggestions for...
Topics: DTIC Archive, Nielsen,Jack N, NIELSEN ENGINEERING AND RESEARCH INC MOUNTAIN VIEW CA, *Aerodynamics,...
If we want to control vortex breakdown on a delta wing of a military aircraft in order to create rolling moments or improve stability at high angle of attack. the use of CFD simulations may help us to improve our understanding of the flow mechanisms that occur with the use of specific control devices. The first step of such studies is to make sure that we can simulate properly and with accuracy vortex breakdown on a delta wing without any control device. At Dassault Aviation we have done some...
Topics: DTIC Archive, Rosenblum, Jean-Pierre, DASSAULT AVIATION SAINT-CLOUD (FRANCE), *VORTICES, *ANGLE OF...
There are several disagreements in the published literature on vortex interaction and bursting data obtained in various wind and water tunnel tests of double-delta wings at high angle of attack (AOA). Theretore a test program was carried out in the Naval Postgraduate School water tunnel using a 76/40 deg. baseline double-delta wing model to investigate the effect of Reynolds number. The program consisted of: (1) Flow vistialisation studies at tunnel speeds of O.2, O.6 and 1.0 ft/sec in the 0-30...
Topics: DTIC Archive, Fritz, Anastasios E., NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *DELTA WINGS, *WATER...
The goal of this study was to better understand the flight of spin-stabilized projectiles at high angle of attack for improved delivery accuracy of indirect fires. Experiments successfully captured flight motions over 40 angle of attack around Mach 0.8 using advanced spark range techniques. Flight analysis validated analytical expressions, kinematics, and dynamics with mass asymmetries, aerodynamic modeling, and parameter estimation algorithms. Significant nonlinearities in angle of attack were...
Topics: DTIC Archive, Fresconi,Frank, Army Research Laboratory Aberdeen Proving Ground United States,...
A summary has been made of the available experimental data on division of normal-force loads between the wing and fuselage of aircraft. Comparison of the experimental values with theoretical calculations which include interference effects show good agreement in general with the greatest differences occurring near a Mach number of 1.0. At high angles of attack, above the range of linear lift curves, the proportion of the total wing-fuselage load carried by the wing decreases and this effect...
Topics: DTIC Archive, GILLIS, CLARENCE L., NATIONAL AERONAUTICS AND SPACE ADMIN LANGLEY RESEARCH CENTER...
This report documents the results of a wind tunnel test conducted to determine the aerodynamic characteristics of unbanked wings from low to high angles of attack at subsonic and transonic speeds. Several wing models with differing planform geometry were tested. All wings were full-span with straight taper, zero trailing-edge sweep, constant bevel angle normal to all edges and constant thickness. The aerodynamic data obtained consisted of normal-force, axial-force, pitching-moment,...
Topics: DTIC Archive, Briggs,M M, NIELSEN ENGINEERING AND RESEARCH INC MOUNTAIN VIEW CA, *AERODYNAMIC...
High-angle strafe is the preferred strafe procedure in the F-16 community. Current tactics do not adequately address the execution of this procedure in mountainous terrain. Current area of operations is extremely mountainous and CWDS does not model complete recovery ground clearance in the event of strafe into rising terrain. Research into approved techniques and analysis of those techniques in mountainous terrain was conducted to determine if safety margins are preserved. In most...
Topics: DTIC Archive, White, Jared P, Air Command And Staff College, Air University Maxwell Air Force Base...
An innovative method of examining fluid flow phenomena is described and preliminary results are given. The technique uses a subproblem formulation which examines only those portions of the flow which are of interest. The particular flow examined is that of a stalled airfoil and the objective of the technique is to develop ways of controlling the stall. Both conventional and nonconventional means of stall control have been examined and it is concluded that the subproblem technique is a viable...
Topics: DTIC Archive, Nixon, David, NIELSEN ENGINEERING AND RESEARCH INC MOUNTAIN VIEW CA, *AERODYNAMICS,...
Bifurcation control is discussed in the context of the stabilization of high angle-of-attack flight dynamics. Two classes of stabilization problems for which bifurcation control is useful are discussed. In the first class, which is emphasized in this presentation, a nonlinear control system operates at an equilibrium point which persists only under very small perturbations of a parameter. Such a system will tend to exhibit a jump, or divergence, instability in the absence of appropriate control...
Topics: DTIC Archive, Abed, E H, MARYLAND UNIV COLLEGE PARK INST FOR SYSTEMS RESEARCH,...
Focused ion beam (FIB) based serial sectioning was utilized to characterize the morphology of two high angle grain boundaries (HAGB) in a nickel based superalloy, one that experienced grain boundary sliding (GBS) and the other experienced strain accumulation, during elevated temperature constant stress loading conditions. A custom script was utilized to serial section and collection-induced secondary electron images from the FIB-SEM system. The MATLAB based MIPARTM software was utilized to...
Topics: DTIC Archive, AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING...
A low-speed wind tunnel investigation was conducted to examine the vortex wake downstream of a three-percent scale model of the YF-17 lightweight fighter prototype at high angles of attack. The study was in support of NASA ames Research Center's wind tunnel investigation of a full scale F/A-18 as part of NASA's High Alpha Technology Program. Smoke flow visualization was used to locate the downstream vortex wake. Hot-wire surveys were taken through the vortex at two stations; one directly aft of...
Topics: DTIC Archive, Frink, William D , Jr, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *FREQUENCY, MODELS,...
This volume contains the 17 papers presented at the AGARD Fluid Dynamics Panel (FDP) Specialists' Meeting on Manoeuvring Aerodynamics held 1st- 2nd May 1991 in Toulouse, France. In addition to these papers, the general discussion held at the end of the meeting and the Technical Evaluation Report are included in this document. This FDP sponsored meeting and document reflect the growing interest in rapid, large-amplitude manoeuvres of aircraft at high angles of attack and highlights the...
Topics: DTIC Archive, ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRANCE),...
Active Control Technology was the subject of this symposium, as it was of a previous FMP/GCP symposium held in 1974. At that time, Active Control could only be viewed in the future - and the view presented at that symposium was very optimistic. Ten years and numerous applications of Active Control Technology later, the view of Active Control which emanated from this symposium was still very optimistic. Certainly some of the projections for significantly reduced tail sizes have been revised in...
Topics: DTIC Archive, ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRANCE),...
This report studies the spatial distribution of X-band, high resolution and high grazing angle polarimetric sea clutter data. The K distribution usually provides a good fit for the distribution of the VV polarised data. The HH polarised data is spikiest and its distribution exhibits a sudden departure from the K distribution in the tail region, which usually requires the KA or the similar distributions to achieve a better fit in the tail region. Due to drawbacks of the KA distribution, this...
Topics: DTIC Archive, Dong, Yunhan, DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION EDINBURGH (AUSTRALIA)...
Forebody Tangential Blowing (FTB) is a pneumatic device that modifies the vortical flow over the forebody of an aircraft operating at high angles of attack. Modified vortical flow in turn creates roll and yaw moments for control. Consequently, it provides a mechanism that could greatly expand the flight envelope of future aircraft systems. One major factor that currently limits the use of FTB as a control effector is that it produces highly nonlinear and uncertain forces. In this work we...
Topics: DTIC Archive, Takahara, Yuji, STANFORD UNIV CA DEPT OF AERONAUTICS AND ASTRONAUTICS, *VORTICES,...
Acoustic propagation in the Arctic is intimately related to the structure of surface pack ice. In this paper, reflection loss and transmission loss are calculated based upon statistical models of ice roughness. Statistical models of ice ridges are introduced and techniques for estimating the roughness spectrum of ridged surfaces are developed. Next, a model for estimating the mean reflection loss is introduced. The reflection loss formulas are based on the statistical models for roughness....
Topics: DTIC Archive, Greene,R R, SCIENCE APPLICATIONS INTERNATIONAL CORP MCLEAN VA, *TRANSMISSION LOSS,...
A water tunnel flow visualization investigation was performed into the high angle of attach aerodynamics of a 2% scale model of the F/A-18 fighter aircraft. The main focus of this study was the effect of pitch rate on the development and bursting of vortices generated from the leading edge extension in the high angle of attack range with and without yaw. Results of this investigation indicate that the vortex bursting point (relative to the static case) moves rearward with increasing pitch-up...
Topics: DTIC Archive, Cavazos, Odilon V , Jr, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *ANGLES, YAW, SCALE...
Laminar boundary flow on cones in supersonic flow was calculated using a modified Method of Integrals to account for the change in velocity profiles in the separated regions. The work was extended to three dimensions and compared to experimental data. Significant progress was made in the modeling of th flows and in particular the regions of separated and reverse flow in the boundary layer.
Topics: DTIC Archive, Holt,Maurice, *SECONDARY FLOW, *SUPERSONIC FLOW, *FLOW SEPARATION, *BOUNDARY LAYER...
The National Advisory Committee for Aeronautics is investigating the possibility of designing a fixed total-pressure tube which will remain insensitive to inclination of the air stream over a wide range of angle of attack throughout the subsonic and supersonic speed ranges. As the first step in this program the variation of total-pressure error with angle of attack of 39 total-pressure tubes has been determined for an angle-of-attack range of + or - 45 deg and an indicated airspeed of 195 miles...
Topics: DTIC Archive, Gracey, William, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY...
A set of aircraft maneuvers has been developed to augment evaluation maneuvers used currently by the flying qualities and flight test communities. These maneuvers extend evaluation to full aircraft dynamics throughout the aircraft flight envelope. As a result, a tie has been established between operational use and design parameters without losing control of the aircraft evaluation process. Twenty maneuvers are described as an initial set to examine primarily high-angle-of attack conditions....
Topics: DTIC Archive, Wilson, David J, MCDONNELL DOUGLAS AEROSPACE ST LOUIS MO, *TEST AND EVALUATION,...
The goal of this research is the control of leading-edge vortex breakdown location utilizing along-the-core blowing near the apex on the leeward surface of sharp-edged, slender, delta wings at high angles of attack. In the S2Ch subsonic wind tunnel at ONERA Chalais Meudon, two delta wing models with 70-deg sweep angles and root chords of 950 mm have been configured to collect qualitative and quantitative surface and flowfield data. First, an examination of the streamwise, time-dependent...
Topics: DTIC Archive, Mitchell, Anthony M, OFFICE NATIONAL D'ETUDES ET DE RECHERCHES AEROSPATIALES MEUDON...
Maintaining vision and consciousness at high sustained +Gz requires a total body effort for most people, and is very fatiguing. Currently, the only pieces of operational G-protective equipment are the anti-G suit and anti-G valve which provide relaxed G-tolerance protection to about 5.5 G. Protection above 5.5 G requires the anti-G straining maneuver (AGSM). Assisted positive pressure breathing (APPB) has been shown to augment sustained +Gz tolerance and reduce the amount of straining necessary...
Topics: DTIC Archive, Burns, John W, SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TX CREW TECHNOLOGY DIV,...
Active controllers are designed and validated to control buffet-induced vibrations in the vertical tails of F/A-18 aircraft during high angle of attack (AOA) maneuvers. First, a procedure is developed to design the offset piezoceramic actuator assemblies, the number of actuators needed, the location of actuators, and the operational power to achieve the needed control authority. The design is limited by the specification of the worst buffet scenario that has been observed during high AOA...
Topics: DTIC Archive, Hanagud, Saythia, GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING,...
Spatial and temporal correlations of high grazing angle high resolution sea clutter collected by the DSTO Ingara polarimetric X-band system are studied. It seems that wavelengths of wind waves and swells are retrievable from the range correlation whereas the periods of the waves and swells are recoverable from the azimuthal correlation. The polarimetric behavior of sea clutter is also studied, and it is found that the Bragg scattering is the dominant scattering mechanism of the sea clutter....
Topics: DTIC Archive, Dong, Yunhan, DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION EDINBURGH (AUSTRALIA)...
It has long been established that supersonic flow over axisymmetric conical bodies at high angles of attack tend to develop a side force due to vortical asymmetry. One of the proposed reasons for the asymmetry is a bifurcation point in the solution of the Navier-Stokes equations. This study investigated the possible existence of a bifurcation point in the Navier-Stokes equations for subsonic flow. Newton's method, with gauss elimination, was used- to solve the steady-state, viscous,...
Topics: DTIC Archive, Waters, Larry K, AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF...
