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This paper discusses the creation of the aerodynamic analysis module of a PC-based aircraft design program called “RDS”, using the time-honored aerodynamic methods found in classical textbooks and the USAF DATCOM. Using this program, reasonably realistic aerodynamic results can be calculated in less than an hour given the geometric inputs which define an aircraft, such as component wetted areas, wing geometry, and cross-section areas. Aerodynamics analysis in RDS includes parasite drag (subsonic and supersonic), drag due to lift, lift curve slope, and maximum lift. Comparisons to T-38 data show good results.

Predictions of the aerodynamic coefficients for a two-slot circulation control airfoil are made by solving the two-dimensional, compressible, mass-averaged, Navier-Stokes equations. Numerical solutions are obtained by using the Beam-Warming implicit approximate factorization technique and the Baldwin-Lomax turbulence model with a curvature correction. Predictions using different combinations of blowing momentum coefficients with each of the two slots are discussed and compared with previous single-slot numerical results.

This paper summarizes an effort to develop and demonstrate an Intelligent Flight Trainer (IFT) for Initial Entry Rotary Wing (IERW) training. Demonstration of concept feasibility relies on an Intelligent Tutoring System (ITS) architecture incorporating Adaptive Training to progressively improve student pilot proficiency. The IFT structure includes: a teacher model which includes algorithmic and expert system assessments of student performance; a domain expert model which maintains knowledge of maneuver criteria and strategies; and a student model which reflects student proficiency. Under an initial feasibility effort we implemented the IFT, integrated it with the UH-1 Training Research Simulator (UH-1TRS) at Fort Rucker, and demonstrated real-time operation in teaching student pilots elementary hover maneuvers.

The architecture and training of artificial neural networks are briefly described. Five applications of these networks to design and analysis problems are presented; three in aerodynamics and two in flight dynamics. The aerodynamics cases are those of a harmonically oscillating airfoil, a pitching delta wing, and airfoil design. The flight dynamic examples involve control of a super maneuver and a decoupled control case. It is demonstrated that highly nonlinear aerodynamic cases can be generalized with sufficient accuracy for design purposes. It is shown that although neural networks generalize well on the aerodynamic problems, they appear lacking comparable robustness in modeling dynamic systems. It is also shown that generalization appears to become weak outside of the training domain.

A quick, computationally inexpensive technique has been developed for the analysis of a full aircraft configuration with iced surfaces. Viscous effects for the flow field about an airfoil with an iced leading edge are accounted for in a thin-layer Navier-Stokes code (ARC2D). A panel code (PMARC) solves the flow field away from the body. The results of the airfoil analysis represent the near-field solutions and are used to modify the boundary conditions in the three-dimensional calculations with the panel code by matching the local circulation. This process is repeated until the total lift coefficient between successive iterations differs by less than a specified value. Examples showing good comparison between the 3-D calculations and experimental data are provided.

NASA and the U.S. Army have designed, developed, and tested a Computer Aiding for Low-Altitude Helicopter Flight guidance system. This system provides guidance to the pilot for near-terrain covert helicopter operations. The guidance is presented to the pilot through symbology on a helmet mounted display. This system has demonstrated the feasibility of a pilot-centered concept of terrain flight guidance that preserves pilot flexibility and authority. The system was developed using extensive piloted simulation and then implemented in a UH-60 Blackhawk helicopter for flight development and evaluation. A close correlation between simulation and actual flight was found; however, in flight overall pilot workload increased and performance decreased. This paper presents a description of the basic system design, simulation, and flight evaluations.

The TW-68 is a civil tilt-wing aircraft proposed by the Ishida Group. Flight simulation was applied to develop the flying qualities of this design. The simulation was accomplished using a mathematical model specially created for this purpose. The effort culminated in piloted evaluations of the simulated aircraft's flight characteristics in a variety of representative mission tasks, both with and without the augmentation of a core Automatic Flight Control System. The paper describes the mathematical model, simulation experiments and results. Flight control laws and their development are also discussed, as are the predicted flight capabilities and limitations of the TW-68.

The implementation of the Future Air Navigation System (FANS) will be evolutionary rather than revolutionary. Different generations of airplane models, each operating in a variety of operating environments will dictate more than a single growth path. How these markets will evolve is a function of our collective ability to assign benefits to specific equipage, to forge new business relationships and to address the market as a global one. Realization of the full benefits of FANS will depend on leadership: who and when.

A computational method was developed for investigating boundary layer control. Solutions of the Reynolds-averaged Navier-Stokes equations were obtained using the two-equation k-∈ turbulence model which includes the low-Reynolds-number effect in the near-wall region. Stream function and vorticity together with the turbulent kinetic energy and its dissipation rate were calculated for the flowfield in a body-fitted coordinate system. By increasing the amount of suction on the upper surface, flow separation could be totally eliminated. Transition from laminar to turbulent flow was delayed. Aerodynamic performance was substantially improved.

A series of Computational Fluid Dynamic (CFD) studies have been performed on a WC-135B aircraft that has been modified at Wright-Patterson AFB (WPAFB) for the Open Skies program. The studies included use of a panel method, full potential method, and Navier Stokes methods in 2-D, axisymmetric, and 3-D. While providing information useful to the Open Skies program, the studies also provide a good example of how lower order and higher order computational aerodynamic methods can be used together to obtain the maximum benefit from CFD. The panel method was used for numerous trade studies to help determine the proper configuration and conditions for the Navier Stokes studies. It also provided for early indications of potential problems that could arise from the Open Skies configuration. As a result, it was also used to test out modifications to the baseline Open Skies contours that were developed in order to minimize the possibility of shock formation over the Open Skies pod.

This paper describes the initiation of an Aeronautical Design Standard (ADS) by the U.S. Army for Helmet Mounted Display (HMD) Symbology. The paper develops the rationale and plan for development of the ADS and describes the requirement for cooperative development of the ADS with professional societies, industry, and government agencies. The importance of ground-based and in-flight simulation activities as an important tool for symbology development and validation are discussed.

Transition to turbulence induced by unstable stationary crossflow vortices in a three-dimensional laminar boundary layer on a Mach 1.5, 25 deg swept wing is investigated with the nonlinear compressible Parabolized Stability Equations (PSE). The wing has 3m span, lm chord, and is untwisted and untapered. Body-fitted coordinates are used to account for all curvature effects of the wing's NACA 64A010 airfoil. The stationary crossflow vortices interact to produce spanwise-periodic harmonics as well as a steady, spanwise-invariant distortion of the underlying laminar flow. The streamwise growth and evolution of all the disturbances is computed for different initial amplitudes of the primary crossflow vortices. For the few initial amplitudes investigated, all the disturbances are found to grow to the point where the mean flow profiles exhibit regions of reversed flow. Beyond this point, the streamwise marching solution is no longer valid.

A unique exercise facility has been developed and used to simulate orbital extravehicular activity (EVA). The device incorporates an arm ergometer into a mechanism which places the subject in the zero-g neutral body posture. The intent of this configuration is to elicit muscular, cardiovascular, respiratory, and thermoregulatory responses similar to those observed during orbital EVA. Experiments done with this facility will help characterize the astronaut's dynamic heat balance during EVA and will eventually lead to the development of an automated thermal control system which would more effectively maintain thermal comfort.

The forming behavior of Al-Cu-Mg-Mn alloy 2024 sheets with fine, equiaxed and coarse, elongated grain structures was characterized in the O temper (fully annealed) and W temper (solution heat treated and quenched) conditions. The fine grained materials had better biaxial stretching capabilities in both tempers. The fine grained O temper also had superior drawing and plane strain stretching properties. For the O temper, conventional tensile forming indicators such as elongation and strain ratio, correlated with ball punch depth, forming limit strains and limiting draw ratio. Such correlations were not apparent in the W temper, however, nor could the two tempers be compared on the basis of tensile data alone.

The cost of development, qualification and certification of new engines has become an extremely high financial burden, both for Governments and private companies at a time when reducing expenditures, cutting research and development budgets, and restructuring organizations are the norm in aerospace industry. The Government acquisition strategy has encouraged contractors to form joint ventures or teaming arrangements in an attempt to glean the best expertise from two companies and then allow the two companies to compete for the production contracts. This concept was palatable and accepted by the industry in the past when they knew a production contract was in the offing. In today's declining defense budget (Figure 1) there is no certainty of production contracts. When the Government does fund a development program, funds are extremely limited. Similarly companies are selectively funding private development efforts. In both cases tight control of costs is a high priority.

A new oil-fringe imaging skin friction (FISF) technique to measure skin friction on wind tunnel models is presented. In the method used to demonstrate the technique, lines of oil are applied on surfaces that connect the intended sets of measurement points, and then a wind tunnel is run so that the oil thins and forms interference fringes that are spaced proportional to local skin friction. After a run the fringe spacings are imaged with a CCD-array digital camera and measured on a computer. Skin friction and transition measurements on a two-dimensional wing are presented and compared with computational predictions.

Mach-flow angularity probes were developed for use in scramjet flow path probe rakes. Prototype probes were fabricated to demonstrate the assembly processes (numerical control machining, furnace brazing, and electron beam welding). Tests of prototype probes confirmed the thermal durability margins and life cycle. Selected probes were calibrated in air at Mach numbers from 1.75 to 6.0. Acceptance criteria for the production probes stressed thermal durability and pressure (and, consequently, Mach number) measurement quality. This new water-cooled MFA probe has 0.397-cm shaft diameter and is capable of withstanding heat fluxes of 2.724 kW/cm2.

In a little over thirty-five years the Auxiliary Power Unit (APU) has evolved from a simple onboard source of starting energy to a flight-essential component for today's commercial transports engaged in Extended Range Twin Engine Operations (ETOPS). In the course of this transition, the APU has progressed from a simple turbomachine to one employing comparable technologies to similarly sized propulsion engines. Reliability, troubleshooting, maintainability, and similar characteristics critical to economical airline operation have necessitated progressively increased sophistication in the design and testing of APUs. Peculiar requirements to APUs, such as totally dependable starting at 40,000 feet and above when cold soaked to -65F exceed the challenges of most propulsion engine systems. This paper addresses the issues facing the APU designer, with particular reference to reliability and maintainability characteristics, major drivers for current APU designs.

Anticipated high agility aircraft will require pilot training and acceleration research to investigate the human capacity to function in the projected environment. Existing man-rated centrifuges and fixed-base simulators are capable of imposing only a portion of the entire envelope of accelerations, and often produce significant artifactual accelerations and illusions. Simulations and engineering analysis of a large radius track centrifuge indicate such a device could impose an acceleration environment suitable for training and research. The technology required for the concept is estimated to be feasible in the near future.

Historically, fusion of metals was accomplished through the use of heat. Cold fusion has become a reality with metal to metal fusion occurring at room temperature. The basics of this new technology which can be done in tank, brush or solid form is covered in this paper.