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(Maximum 200 words) A laboratory experiment was conducted to quantify the annoyance response of people on the ground to en route noise generated by aircraft at cruise conditions. The en route noises were ground-level recordings of eight advanced turboprop aircraft flyovers and six conventional turbofan flyovers. The eight advanced turboprop en route noises represented the NASA Propfan Test Assessment aircraft operating at different combinations of altitude, aircraft Mach number, and propeller tip speed. The conventional turbofan en route noises represented six different commercial airliners. The overall durations of the en route noises varied from approximately 40 to 160 sec. In the experiment, 32 subjects judged the annoyance of the en route noises as well as recordings of both the takeoff and landing noises of each of 5 conventional turboprop and 5 conventional turbofan aircraft. Each of the noises was presented at three sound pressure levels to the subjects in an anechoic listening..

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(Maximum 200 words) The transmission of large amounts of power in space by laser beam (diode lasers, in particular) requires an array of lasers to increase total power. Concentration of the beam requires some degree of coherence. Temporal coherence can be obtained by locking amplifiers to a master oscillator. However, spatial coherence is not so easily created or maintained. Many mechanical, thermal, and electrical factors oppose it continually. A very simple method is described for creating and maintaining a degree of spatial coherence by simply turning selected diodes ON or OFF. The degree of coherence can be chosen; the greater the coherence, the larger is the number of lasers required for a given power and the longer the lifetime of the array. An experiment for analyzing performance, verifying theory, and evaluating critical parameters is also proposed. 14. SUBJECT TERMS 15. NUMBER OF PAGES Phased arrays; Laser diodes 9 16. PRICE CODE A02 17. SECURITY CLASSIFICATION 18. SECURI..

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(Maximum 200 words) A theory for representing a parameter-dependent function as a function trajectory is described, along with the theory for determining a piecewise analytic fit to the trajectory. An example is given that illustrates the application of the theory to generating a smooth surface through a discrete set of input cross-section shapes. A simple procedure for smoothing in the parameter direction is presented, along with a computed example. Application of the theory to aerodynamic surface modeling is demonstrated by applying it to a blended wingfuselage surface. 14. SUBJECT TERMS 15. NUMBER OF PAGES Geometry modeling; Analytic modeling; Surface grid generation 13 16. PRICE CODE A03 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF REPORT OF THIS PAGE OF ABSTRACT OF ABSTRACT Unclassified Unclassified NSN 7540-01-280-5500 Standard Form 298(Rev. 2-89) Prescribed by ANSI Std. Z39-18 298-102 NASA-Langley, Abstract A the..

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(Maximum 200 words) An analysis of flight measurementsmade near a wake vortex was conducted to explore the feasibility of providing a pilot with useful wake-avoidance information. The measurements were made with relatively low-cost flow and motion sensors on a light airplane flying near the wake vortex of a turboprop airplane weighing approximately 90000 lb. Algorithms were developed which removed the response of the airplane to control inputs from the total airplane response and produced parameters which were due solely to the flow field of the vortex. These parameters were compared with values predicted by potential theory. The results indicated that the presence of the vortex could be detected by a combination of parameters derived from the simple sensors. However, the location and strength of the vortex cannot be determined without additional and more accurate sensors. 14. SUBJECT TERMS 15. NUMBER OF PAGES Wake vortex, Aircraft safety, and Airborne hazard detection 36 16. PRICE ..

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(Maximum 200 words) A procedure for tailoring a blended wing-body configuration to reduce its computed wave drag is described. The method utilizes an iterative algorithm within the framework of first-order linear theory. Four computed examples are included. In each case, the zero-lift wave drag was reduced without an increase in drag due to lift. 14. SUBJECT TERMS 15. NUMBER OF PAGES Supersonic aircraft design; Blended wing-body; Low-drag design 17 16. PRICE CODE A03 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF REPORT OF THIS PAGE OF ABSTRACT OF ABSTRACT Unclassified Unclassified NSN 7540-01-280-5500 Standard Form 298(Rev. 2-89) Prescribed by ANSI Std. Z39-18 298-102 NASA-Langley, Abstract A procedure for tailoring a blended wing-body configuration to reduce its computed wave drag is described. The method utilizes an iterative algorithm within the framework of first-order linear theory. Four computed examples are inclu..

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(Maximum 200 words) The effect of low-speed impact damage on the compression and tension strength of thin and moderately thick composite specimens was investigated. Impact speeds ranged from 50 to 550 ft/sec, with corresponding impact energies from 0.25 to 30.7 ft-lb. Impact locations were at the center of the specimen or near a lateral unloaded edge. In this study, thin specimens with only 90 ffi and \Sigma45 ffi plies that were impacted away from the unloaded edge suffered less reduction in maximum load-carrying capability because of impact damage than the same specimens impacted near the unloaded edge. Failure loads of thicker compression-loaded specimens with a similar stacking sequence were independent of impact location. Failure loads of thin tension-loaded specimens with 0 ffi plies were independent of impact location, whereas failure loads of thicker compressionloaded specimens with 0 ffi plies were dependent upon impact location. A finite-element analysis indicated th..

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(Maximum 200 words) This paper presents the forward position and velocity kinematics for the redundant eight-degree-of-freedom Advanced Research Manipulator II (ARMII). Inverse position and velocity kinematic solutions are also presented. The approach in this paper is to specify two of the unknowns and solve for the remaining six unknowns. Two unknowns can be specified with two restrictions. First, the elbow joint angle and rate cannot be specified because they are known from the end-effector position and velocity. Second, one unknown must be specified from the four-jointed wrist, and the second from joints that translate the wrist, elbow joint excluded. There are eight solutions to the inverse position problem. The inverse velocity solution is unique, assuming the Jacobian matrix is not singular. A discussion of singularities is based on specifying two joint rates and analyzing the reduced Jacobian matrix. When this matrix is singular, the generalized inverse may be used as an altern..

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(Maximum 200 words) One of the Grand Challenges of the Federal High Performance Computing and Communications (HPCC) Program is in remote exploration and experimentation (REE). The goal of the REE Project is to develop a space-borne computing technology base that will enable the next generation of missions to explore the Earth and the Solar System. This paper discusses an ongoing study that uses a recent development in communication control technology to implement hybrid hypercube structures. These architectures are similar to binary hypercubes, but they also provide added connectivity between the processors. This added connectivity increases communication reliability while decreasing the latency of interprocessor message passing. Because these factors directly determine the speed that can be obtained by multiprocessor systems, these architectures are attractive for applications such as REE, where high performance and ultrareliability are required. This paper describes and enumerates t..

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(Maximum 200 words) A parametric study is presented of the buckling behavior of infinitely long, symmetrically laminated anisotropic plates subjected to combined loadings. The loading conditions considered are axial tension and compression, transverse tension and compression, and shear. Results obtained using a special-purpose analysis, well-suited for parametric studies, are presented for clamped and simply supported plates. Moreover, results are presented for some common laminate constructions, and generic buckling design charts are presented for a wide range of parameters. The generic design charts are presented in terms of useful nondimensional parameters, and the dependence of the nondimensional parameters on laminate fiber orientation, stacking sequence, and material properties is discussed. An important finding of the study is that the effects of anisotropy are much more pronounced in shear-loaded plates than in compression-loaded plates. In addition, the effects of anisotropy ..

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(Maximum 200 words) A survey of research on drag-due-to-lift minimization at supersonic speeds, including a study of the effectiveness of current design and analysis methods, has been conducted. The results show that a linearized theory analysis with estimated attainable thrust and vortex force effects can predict with reasonable accuracy the lifting efficiency of flat wings. Significantly better wing performance can be achieved through the use of twist and camber. Although linearized theory methods tend to overestimate the amount of twist and camber required for a given application and provide an overly optimistic performance prediction, these deficiencies can be overcome by implementation of recently developed empirical corrections. Numerous examples of the correlation of experiment and theory are presented to demonstrate the applicability and limitations of linearized theory methods with and without empirical corrections. The use of an Euler code for the estimation of aerodynamic c..