Stories
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Briefs: Mechanical & Fluid Systems
Program for Computing Dynamics of Multiple Bodies
Symbolic Generator-Based Efficient Multibody Dynamics Algorithm (SOMBAT) is a program that enables speedy and accurate computations that solve equations of motion of multiple bodies. Originally intended for space-based applications (i.e., solving equations for the dynamics of a cluster of flexible...
Briefs: Mechanical & Fluid Systems
A leak-free valve has been proposed as a more reliable, less expensive, adaptable alternative to a one-time-opening, pyrotechnically actuated valve (pyrovalve). In the original intended application, the pyrovalve...
Briefs: Mechanical & Fluid Systems
Pneumatic cushions have been proposed for protecting the afterbodies of two-body instrumented soil-penetrator projectiles. These cushions would be, essentially, doughnut-shaped...
Briefs: Mechanical & Fluid Systems
Work performed at Johnson Space Center has brought about a major improvement in the means for measuring the bending that occurs whenever stress is applied to a bolted joint. This major improvement is a...
Briefs: Mechanical & Fluid Systems
Using Electromagnetic Drag on Tethers To De-Orbit Spacecraft
Two papers propose the use of electrically conductive tethers to remove spent or dysfunctional spacecraft from orbit around the Earth in order to reduce the hazard of orbital debris. In comparison with onboard rockets, these tethers would be more cost-effective, more reliable, and less...
Briefs: Mechanical & Fluid Systems
The spherical-coordinates encoder module (SCEM) is a relatively simple and inexpensive electromechanical apparatus for quickly and easily measuring three-dimensional offsets between objects at distances of...
Briefs: Mechanical & Fluid Systems
The figure illustrates a chair-base mechanism with a bushing-mounted drag chain. The bushing-mount design provides for one end of the drag chain to be free to pivot; this provision makes it possible to wrap the drag...
Briefs: Mechanical & Fluid Systems
Computational simulations and wind-tunnel tests have demonstrated the feasibility of using inflatable boots on the leading edges of airplane wings, both as devices to increase lift and as...
Briefs: Mechanical & Fluid Systems
A nonintrusive flow-measurement system based on ultrasonics has been developed to replace a system based on turbine flowmeters. A turbine flowmeter must be mounted in line with a pipe; this raises the...
Briefs: Mechanical & Fluid Systems
A boundary-layer rake of pitot tubes has been designed and built for installation on a flight-test fixture (FTF) on the NASA Dryden F-15B, which is a two-seat version of the F-15...
Briefs: Mechanical & Fluid Systems
A 3D Navier-Stokes CFD Code for Analysis of Turbomachinery
The ADPAC software is a computational fluid dynamics (CFD) code for analysis of flows in turbomachines. The outstanding feature of ADPAC is the ability to solve the Navier-Stokes equations for complex three-dimensional (3D) flow fields that include multiple flow paths, and the modeling of...
Briefs: Mechanical & Fluid Systems
Low-Energy Interplanetary Transfers Using Lagrangian Points
A paper summarizes early findings from a continuing study of the dynamics of the transport and distribution of matter within the Solar system. In the study, the stable and unstable manifolds of the periodic and quasi-periodic orbits around the Lagrangian points L1 and L2 of the Sun/planet...
Briefs: Mechanical & Fluid Systems
Digital PIV Measurements of Flow in a Centrifugal Compressor
A report describes experiments in which digital particle-image velocimetry (digital PIV) was used to measure the flow field in the diffuser of a high-speed centrifugal compressor. In digital PIV, a sheet of pulsed laser light illuminates a flow field seeded with small tracer particles,...
Briefs: Mechanical & Fluid Systems
A suite of five computational fluid dynamics (CFD) codes has been developed for analysis of flows in turbomachinery. Two of the codes are used to generate two-dimensional (2-D) or...
Briefs: Mechanical & Fluid Systems
The P-Finite Element Integrated Thermal-Structural Program (PITS 2D) solves the equations for the combined effects of thermal expansion and elasticity in a two-dimensional or an...
Briefs: Mechanical & Fluid Systems
Mathematical models to approximate the dynamics of aircraft are often generated by considering aircraft structures to be rigid bodies. These models may be unsuitable for evaluating the...
Briefs: Mechanical & Fluid Systems
A continuing program of research is directed toward the development of crashworthy composite-material fuselages for small aircraft. These fuselages are required not only to withstand...
Briefs: Mechanical & Fluid Systems
Computational Test Cases for a Rectangular Supercritical Wing
A report describes wind-tunnel experiments on a rectangular supercritical wing and presents test cases that have been selected from the archived sets of experimental data for comparison with computational fluid dynamics (CFD) predictions. In the experiments, the wing was driven in...
Briefs: Mechanical & Fluid Systems
Kinetic-energy-absorbing shrouds have been proposed to protect nearby persons and equipment against high-speed debris ejected by disintegrating machines. Examples of machines that could...
Briefs: Mechanical & Fluid Systems
Equations have been derived to describe the deflection of a circular membrane under both in-plane and transverse loads. More specifically, the equations describe the radial (in-plane)...
Briefs: Mechanical & Fluid Systems
A mixing apparatus combines liquid oxygen and liquid nitrogen to make liquid air in small, convenient quantities. Heretofore, equipment used to make liquid air by mixing was incapable of making...
Briefs: Mechanical & Fluid Systems
"Hybrisol" denotes a proposed rocket engine that would contain hybrid and solid-propellant parts within a single combustion chamber. ["Hybrid" as used here denotes a type of rocket engine in which a solid fuel is burned...
Briefs: Mechanical & Fluid Systems
Accelerations of One Airplane in Wake Vortices of Another
Accelerations of one airplane encountering a vortex or pair of vortices in the wake of another airplane were computed in a parametric study. The approach taken in the study was to systematically investigate the effects of progressively more nearly complete descriptions of the interaction of...
Briefs: Mechanical & Fluid Systems
Conservatism in Deterministic Structural Analysis
A paper discusses the excessive conservatism that has long been suspected to exist, because of the use of conventional (deterministic) safety factors, in the analysis and design of quasi-static structures. The origin of this conservatism is identified as a violation of statistical error-propagation...
Briefs: Mechanical & Fluid Systems
Experiments on Vibration and Noise in Fuselages
A paper summarizes a continuing program of vibro-acoustic testing of two aircraft fuselage structures: (1) a 12-ft (3.7-m)-long generic aluminum test-bed cylinder that contains stiffening rings and stringers and (2) the 40-ft (12.2-m)-long fuselage of a 10-passenger turboprop airplane, made of...
Briefs: Mechanical & Fluid Systems
FoilSim is a computer program that calculates and graphically depicts information on flows of air around airfoils of various shapes. Although it is useful primarily as a teaching tool to enhance...
Briefs: Mechanical & Fluid Systems
Current proposed shapes for single-stage-to-orbit vehicles like the Lockheed-Martin X-33 and VentureStar reusable launch vehicle have extremely large base areas when compared with...
Briefs: Mechanical & Fluid Systems
A process for the fabrication of a polycrystalline diamond membrane involves chemical vapor deposition (CVD) of diamond onto a silicon substrate, followed by conventional...
Briefs: Mechanical & Fluid Systems
NASA's F-15B #836 is a two-seat version of the F-15, which is a high-performance, supersonic, all-weather fighter airplane. The F-15B is used as a test-bed aircraft for a wide variety of...
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