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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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Discussion of the paper, Some Aspects of Propulsion for the Augmenter-Wing Concept, by D. C. Whittley

Many modern concepts for STOL and V/STOL aircraft rely on integration of the propulsion system with the wing to create favorable lift interactions, and are known as powered lift concepts. A study of powered lift, concerning management and control of the various propulsive streams or jets is presented, each concept having its own particular objectives and requirements. Some specific objectives of this kind are described which relate to the augmentor wing. Consideration is given to three aspects of the subject, namely the augmentor flap itself, the wind ducting and augmentor primary nozzle, and the choice of powerplant or engine cycle. More generally, comments are made regarding noise attenuation and the prospect for achieving a low overall noise level for jet STOL aircraft of the future.

Schmitt, H.↗
NASA NTRS1986

Planetary exploration through year 2000: An augmented program. Part two of a report by the Solar System Exploration Committee of the NASA Advisory Council

In 1982, the NASA Solar System Exploration Committee (SSEC) published a report on a Core Program of planetary missions, representing the minimum-level program that could be carried out in a cost effective manner, and would yield a continuing return of basic scientific results. This is the second part of the SSEC report, describing missions of the highest scientific merit that lie outside the scope of the previously recommended Core Program because of their cost and technical challenge. These missions include the autonomous operation of a mobile scientific rover on the surface of Mars, the automated collection and return of samples from that planet, the return to Earth of samples from asteroids and comets, projects needed to lay the groundwork for the eventual utilization of near-Earth resources, outer planet missions, observation programs for extra-solar planets, and technological developments essential to make these missions possible.

Source record↗
NASA NTRS1986

Study of onboard expert systems to augment space shuttle and space station autonomy

The feasibility of onboard crew activity planning was examined. The use of expert systems technology to aid crewmembers in locating stowed equipment was also investigated. The crew activity planning problem, along with a summary of past and current research efforts, was discussed in detail. The requirements and specifications used to develop the crew activity planning system was also defined. The guidelines used to create, develop, and operate the MFIVE Crew Scheduler and Logistics Clerk were discussed. Also discussed is the mathematical algorithm, used by the MFIVE Scheduler, which was developed to aid in optimal crew activity planning.

Kurtzman, C. R.↗
NASA NTRS1985

Expert systems and their use in augmenting design optimization

The challenging requirements that are evolving for future aircraft demand that each design be optimally integrated, for the penalties imposed by nonoptimal performance are significant. Classic numerical optimization algorithms have been and will continue to be important tools for aircraft designers. These methods are, however, limited to certain categories of aircraft design variables, leaving the remainder to be determined by the user. A method that makes use of knowledge-based expert systems offers the potential for aiding the conceptual design process in a way that is similar to that of numerical optimization, except that it would address discrete, discontinuous, abstract, or any other unoptimized aspect of vehicle design and integration. Other unique capabilities such as automatic discovery and learning in design may also be achievable in the near term. This paper discusses current practice in conceptual aircraft design and knowledge-based systems, and how knowledge-based systems can be used in conceptual design.

Kidwell, G. H.↗
NASA NTRS1986

Thermophoretically augmented mass transfer rates to solid walls across laminar boundary layers

Predictions of mass transfer (heavy vapor and small particle deposition) rates to solid walls, including the effects of thermal (Soret) diffusion ('thermophoresis' for small particles), are made by numerically solving the two-dimensional self-similar forced convection laminar boundary-layer equations with variable properties, covering the particle size range from vapor molecules up to the size threshold for inertial (dynamical nonequilibrium) effects. The effect of thermophoresis is predicted to be particularly important for submicron particle deposition on highly cooled solid surfaces, with corresponding enhancement factors at atmospheric conditions being over a thousand-fold at T(w)/T(e) equal to about 0.6. As a consequence of this mass transfer mechanism, the particle size dependence of the mass transfer coefficient to a cooled wall will be much weaker than for the corresponding case of isothermal capture by Brownian-convective diffusion.

Gokoglu, S. A.↗
NASA NTRS1986

Development of sensor augmented robotic weld systems for aerospace propulsion system fabrication

In order to meet stringent performance goals for power and reuseability, the Space Shuttle Main Engine was designed with many complex, difficult welded joints that provide maximum strength and minimum weight. To this end, the SSME requires 370 meters of welded joints. Automation of some welds has improved welding productivity significantly over manual welding. Application has previously been limited by accessibility constraints, requirements for complex process control, low production volumes, high part variability, and stringent quality requirements. Development of robots for welding in this application requires that a unique set of constraints be addressed. This paper shows how robotic welding can enhance production of aerospace components by addressing their specific requirements. A development program at the Marshall Space Flight Center combining industrial robots with state-of-the-art sensor systems and computer simulation is providing technology for the automation of welds in Space Shuttle Main Engine production.

Jones, C. S.↗
NASA NTRS1986

Passive damping augmentation for flexible structures

The present work concentrates on the application and extension of absorber design and optimization techniques to a multimode, multi-DOF, large space structure, namely the NASA space station. The principal issue addressed is the optimal tuning of several absorbers for the transient response of a multi-DOF system, including the effects of modal coupling, existing structural damping, absorber placement, and adsorber mass. The space station is subject to many transient disturbances such as docking, orbit reboost, crew motion, and payload slewing. A notable steady-state excitation source is the Science Research Centrifuge, which rotates at a frequency in the bandwidth of the primary structural modes. Because of the relatively advanced state of development of steady-state absorber design techniques, only the transient cases are considered in this study.

Sesak, J. R.↗
NASA NTRS1987

Range filtering for sequential GPS receivers with external sensor augmentation

The filtering of the satellite range and range-rate measurements from single channel sequential Global Positioning System receivers is usually done with an extended Kalman filter which has state variables defined in terms of an orthogonal navigation reference frame. An attractive suboptimal alternative is range-domain filtering, in which the individual satellite measurements are filtered separately before they are combined for the navigation solution. The main advantages of range-domain filtering are decreased processing and storage requirements and simplified tuning. Several range filter mechanization alternatives are presented, along with an innovative approach for combining the filtered range-domain quantities to determine the navigation state estimate. In addition, a method is outlined for incorporating measurements from auxiliary sensors such as altimeters into the navigation state estimation scheme similarly to the satellite measurements. A method is also described for incorporating inertial measurements into the navigation state estimator as a process driver.

Paielli, Russell↗
NASA NTRS1987

Digital control of highly augmented combat rotorcraft

Proposed concepts for the next generation of combat helicopters are to be embodied in a complex, highly maneuverable, multiroled vehicle with avionics systems. Single pilot and nap-of-the-Earth operations require handling qualities which minimize the involvement of the pilot in basic stabilization tasks. To meet these requirements will demand a full authority, high-gain, multimode, multiply-redundant, digital flight-control system. The gap between these requirements and current low-authority, low-bandwidth operational rotorcraft flight-control technology is considerable. This research aims at smoothing the transition between current technology and advanced concept requirements. The state of the art of high-bandwidth digital flight-control systems are reviewed; areas of specific concern for flight-control systems of modern combat are exposed; and the important concepts are illustrated in design and analysis of high-gain, digital systems with a detailed case study involving a current rotorcraft system. Approximate and exact methods are explained and illustrated for treating the important concerns which are unique to digital systems.

Tischler, Mark B.↗
NASA NTRS1987

The scaling of model test results to predict intake hot gas reingestion for STOVL aircraft with augmented vectored thrust engines

The difficulties of modeling the complex recirculating flow fields produced by multiple jet STOVL aircraft close to the ground have led to extensive use of experimental model tests to predict intake Hot Gas Reingestion (HGR). Model test results reliability is dependent on a satisfactory set of scaling rules which must be validated by fully comparable full scale tests. Scaling rules devised in the U.K. in the mid 60's gave good model/full scale agreement for the BAe P1127 aircraft. Until recently no opportunity has occurred to check the applicability of the rules to the high energy exhaust of current ASTOVL aircraft projects. Such an opportunity has arisen following tests on a Tethered Harrier. Comparison of this full scale data and results from tests on a model configuration approximating to the full scale aircraft geometry has shown discrepancies between HGR levels. These discrepancies although probably due to geometry and other model/scale differences indicate some reexamination of the scaling rules is needed. Therefore the scaling rules are reviewed, further scaling studies planned are described and potential areas for further work are suggested.

Penrose, C. J.↗
NASA NTRS1986

Artificial intelligence for Space Station automation: Crew safety, productivity, autonomy, augmented capability

Artificial intelligence (AI) R&D projects for the successful and efficient operation of the Space Station are described. The book explores the most advanced AI-based technologies, reviews the results of concept design studies to determine required AI capabilities, details demonstrations that would indicate the existence of these capabilities, and develops an R&D plan leading to such demonstrations. Particular attention is given to teleoperation and robotics, sensors, expert systems, computers, planning, and man-machine interface.

Firschein, O.↗
NASA NTRS1986

Local heat transfer augmentation in channels with two opposite ribbed surfaces

The local heat transfer coefficient distribution of a square channel with two opposite ribbed walls was determined. The square channel was connected to a sudden contraction entrance in order to simulate the inlet condition of the turbine blade cooling passages. The test channel was heated by thin stainless steel foils with a thickness of 0.000025 m, and instrumented with 180 thermocouples. The brass ribs of a square cross-section were glued periodically, in line, onto the top and bottom walls of the foil-heated channel in patterns to achieve the desired spacing and angle-of-attack. The local heat transfer coefficients on the smooth side and the ribbed side walls, at the channel entrance and the downstream regions, were measured for eight rib configurations and three Reynolds numbers (Re = 10,000, 30,000, and 60,000).

Han, J. C.↗
NASA NTRS1987

Dynamic stability and handling qualities tests on a highly augmented, statically unstable airplane

Novel flight test and analysis techniques in the flight dynamics and handling qualities area are described. These techniques were utilized at NASA Ames-Dryden during the initial flight envelope clearance of the X-29A aircraft. It is shown that the open-loop frequency response of an aircraft with highly relaxed static stability can be successfully computed on the ground from telemetry data. Postflight closed-loop frequency response data were obtained from pilot-generated frequency sweeps and it is found that the current handling quality requirements for high-maneuverability aircraft are generally applicable to the X-29A.

Gera, Joseph↗
NASA NTRS1988

An application of active surface heating for augmenting lift and reducing drag of an airfoil

Application of active control to separated flow on the RC(6)-08 airfoil at high angle of attack by localized surface heating is numerically simulated by integrating the compressible 2-D nonlinear Navier-Stokes equation solver. Active control is simulated by local modification of the temperature boundary condition over a narrow strip of the upper surface of the airfoil. Both mean and perturbed profiles are favorably altered when excited with the same natural frequency of the shear layer by moderate surface heating for both laminar and turbulent separation. The shear layer is found to be very sensitive to localized surface heating in the vicinity of the separation point. The excitation field at the surface sufficiently altered both the local as well as the global circulation to cause a significant increase in lift and reduction in drag.

Maestrello, Lucio↗
NASA NTRS1987

Dynamic stability and handling qualities tests on a highly augmented, statically unstable airplane

This paper describes some novel flight tests and analysis techniques in the flight dynamics and handling qualities area. These techniques were utilized during the initial flight envelope clearance of the X-29A aircraft and were largely responsible for the completion of the flight controls clearance program without any incidents or significant delays. The resulting open-loop and closed-loop frequency responses and the time history comparison using flight and linear simulation data are discussed.

Gera, Joseph↗
NASA NTRS1988

Eigenstructure assignment for the control of highly augmented aircraft

Eigenstructure assignment is utilized to design flight control laws for aircraft with many control effectors. It is shown that a previous eigenstructure design for the flight propulsion control coupling (FPCC) aircraft lateral dynamics with three control surfaces exhibits a lack of stability robustness because the control distribution matrix is nearly rank-deficient. A method is mapped back, reducing the control space to two dimensions by using the singular value decomposition. After the design is complete, the controller is mapped back to the original three-dimensional control space. This design approach yields a controller with both smaller gains and improved multivariable stability margins at the aircraft inputs. An interesting characteristics of the control mapping, as applied to the given example, is that the most effective inputs have the larger gains while the less effective inputs have smaller gains.

Sobel, Kenneth M.↗