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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Retro Rocket Motor Self-Penetrating Scheme for Heat Shield Exhaust Ports

A preliminary scheme was developed for base-mounted solid-propellant retro rocket motors to self-penetrate the Orion Crew Module heat shield for configurations with the heat shield retained during landings on Earth. In this system the motors propel impactors into structural push plates, which in turn push through the heat shield ablator material. The push plates are sized such that the remaining port in the ablator material is large enough to provide adequate flow area for the motor exhaust plume. The push plate thickness is sized to assure structural integrity behind the ablative thermal protection material. The concept feasibility was demonstrated and the performance was characterized using a gas gun to launch representative impactors into heat shield targets with push plates. The tests were conducted using targets equipped with Fiberform(R) and PICA as the heat shield ablator material layer. The PICA penetration event times were estimated to be under 30 ms from the start of motor ignition. The mass of the system (not including motors) was estimated to be less than 2.3 kg (5 lbs) per motor. The configuration and demonstrations are discussed.

landing system↗
NASA NTRS2020

Space Launch System Mobile Launcher Modal Pretest Analysis

NASA is developing an expendable heavy lift launch vehicle capability, the Space Launch System, to support lunar and deep space exploration. To support this capability, an updated ground infrastructure is required including modifying an existing Mobile Launcher system. The Mobile Launcher is a very large heavy beam/truss steel structure designed to support the Space Launch System during its buildup and integration in the Vehicle Assembly Building, transportation from the Vehicle Assembly Building out to the launch pad, and provides the launch platform at the launch pad. The previous Saturn/Apollo and Space Shuttle programs had integrated vehicle ground vibration tests of their integrated launch vehicles performed with simulated free-free boundary conditions to experimentally anchor and validate structural and flight controls analysis models. For the Space Launch System program, the Mobile Launcher will be used as the modal test fixture for the ground vibration test of the first Space Launch System flight vehicle, Exploration Mission ? 1( now referred to as Artemis 1), programmatically referred to as the Integrated vehicle modal test. The Integrated vehicle modal test of the Exploration Mission - 1 integrated launch vehicle will have its core and second stages unfueled while mounted to the ML while inside the Vehicle Assembly Building, which is currently scheduled for the late spring or early summer of 2020. The Space Launch System program has implemented a building block approach for dynamic model validation. The modal test of the Mobile Launcher is an important part of this building block approach in supporting the integrated vehicle modal test since the Mobile Launcher will serve as a structurally dynamic test fixture whose modes will couple with the modes of the Exploration Mission ? 1 test vehicle. The Mobile Launcher modal test will further support understanding the structural dynamics of the Mobile Launcher and SLS during rollout to the launch pad, which will play a key role in better understanding and prediction of the rollout forces acting on the launch vehicle. The Mobile Launcher modal test is currently scheduled for the summer of 2019. Due to a very tight modal testing schedule, this Mobile Launcher modal pretest analysis has been performed to ensure there is a high likelihood of being able to successfully complete the modal test (i.e. identify the primary target modes) using the planned instrumentation, shakers, and excitation types. This paper will discuss this Mobile Launcher modal pretest analysis and the unique challenges faced due to the Mobile Launcher's size and weight, which are typically not faced when modal testing aerospace structures.

Akers, James C.↗
NASA NTRS2016

Meta-shell Approach for Constructing Lightweight and High Resolution X-Ray Optics

Lightweight and high resolution optics are needed for future space-based x-ray telescopes to achieve advances in high-energy astrophysics. Past missions such as Chandra and XMM-Newton have achieved excellent angular resolution using a full shell mirror approach. Other missions such as Suzaku and NuSTAR have achieved lightweight mirrors using a segmented approach. This paper describes a new approach, called meta-shells, which combines the fabrication advantages of segmented optics with the alignment advantages of full shell optics. Meta-shells are built by layering overlapping mirror segments onto a central structural shell. The resulting optic has the stiffness and rotational symmetry of a full shell, but with an order of magnitude greater collecting area. Several meta-shells so constructed can be integrated into a large x-ray mirror assembly by proven methods used for Chandra and XMM-Newton. The mirror segments are mounted to the meta-shell using a novel four point semi-kinematic mount. The four point mount deterministically locates the segment in its most performance sensitive degrees of freedom. Extensive analysis has been performed to demonstrate the feasibility of the four point mount and meta-shell approach. A mathematical model of a meta-shell constructed with mirror segments bonded at four points and subject to launch loads has been developed to determine the optimal design parameters, namely bond size, mirror segment span, and number of layers per meta-shell. The parameters of an example 1.3 m diameter mirror assembly are given including the predicted effective area. To verify the mathematical model and support opto-mechanical analysis, a detailed finite element model of a meta-shell was created. Finite element analysis predicts low gravity distortion and low thermal distortion. Recent results are discussed including Structural Thermal Optical Performance (STOP) analysis as well as vibration and shock testing of prototype meta-shells.

Lightweight and high resolution optics↗
DOE OSTI2021

Economic solution for low carbon process heat: A horizontal, compact high temperature gas reactor

In 2018, nuclear energy generated 55% of United States’ and one third of the world’s carbon free electricity, making nuclear energy a key tool in efforts to mitigate climate change before 2050. However, the current nuclear technology, light water reactors (LWRs), is limited to 300°C, so it cannot be used to decarbonize industrial process heat which accounts for 12% of US greenhouse gas emissions. High temperature gas reactors (HTGRs) can meet the high temperature demand with carbon free nuclear heat. The estimated cost of HTGRs, such as the Next Generation Nuclear Plant (NGNP), are even higher than state-of-the-art LWRs. In this paper, we expanded our nuclear cost estimating tool to include HTGRs and find that the NGNP overnight capital costs were 32% higher than an advanced LWR per unit capacity. The higher cost will naturally result in larger risk to cost overrun as recently experienced by larger LWRs in western nations. With a design-to-build mindset to minimize cost and construction risk, we introduce the horizontal, compact HTGR (HC-HTGR). The reactor core and steam generator are mounted horizontally on rails and in-line with one another, decreasing the size of the reactor building relative to the power capacity four times when compared to traditional HTGRs. The HC-HTGR reduced overnight civil structure costs by 42%, indirect costs by 38%, and total capital costs by 20% from NGNP. We discussed the required engineering of new systems for the HC-HTGR including vessel supports, the reactor cavity cooling system, and steam generator design. Finally, we estimated the fuel and operations costs of the HC-HTGR, and a survey of low-carbon industrial process heat technology showed the HC-HTGR can deliver a highly competitive levelized cost of heat in the range of $6.13–12.48/GJ.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1974

A detailed investigation of flight buffeting response at subsonic and transonic speeds

The structural response to aerodynamic buffeting during moderate-to-high-g maneuvers was investigated. Dynamic response data measured during a flight loads program were analyzed to obtain power spectra and rms values of response for 19 sensors mounted on the test aircraft. In this paper, peaks in the power spectra of accelerations measured at the wing tips, center of gravity and pilot's seat, and wing vertical shear, bending moment and torsional moments are correlated with natural vibration modes. The amplitudes of response are compared to show effects of angle of attack, sensor type and location, Mach number, and altitude.

Benepe, D. B.↗
NASA NTRS1978

Implications of cavity, topographic and geologic influences on tilt and strain observations

Tilt and strain observations are importantly (pathologically at the 100%, typically at the few 10s% level) affected by cavities, topography, and geological inhomogenities; gravity observation are practically unaffected. The traditional earth tide observatory and abandoned mine or tunnel is a very poor place to measure body tides because of the complicated cavities, topography and geology. Instead, the ideal site for observing the body tide is in flat terrain with horizontally layered, mechanically homogeneous geology. Strain will be measured with long surface- or trench-mounted laser strain meters and tilt with long, surface- or trench mounted liquid levels, or with borehole tiltmeters. Horizontal geological discontinuities can produce large perturbations of the tilt and strain tides, and these perturbations, using the known homogeneous tidal strains and tilts, can be used in exploring local structure in favorable cases and, through possible time variations of tidal admittances, in predicting earthquakes.

Harrison, J. C.↗
NASA NTRS1981

Structural dynamics verification facility study

The need for a structural dynamics verification facility to support structures programs was studied. Most of the industry operated facilities are used for highly focused research, component development, and problem solving, and are not used for the generic understanding of the coupled dynamic response of major engine subsystems. Capabilities for the proposed facility include: the ability to both excite and measure coupled structural dynamic response of elastic blades on elastic shafting, the mechanical simulation of various dynamical loadings representative of those seen in operating engines, and the measurement of engine dynamic deflections and interface forces caused by alternative engine mounting configurations and compliances.

Kiraly, L. J.↗
NASA NTRS1982

Control of large space structures and associated precision-pointed payloads

Stability and robustness of a two-level control system for large space structures were investigated. In particular, the effects of actuator/sensor nonlinearities and dynamics on the closed-loop stability were studied and the problem of control-systems design for fine-pointing of several individually pointed payloads mounted on a large space platform was examined. A composite controller is proposed and is stable and robust.

Joshi, S. M.↗
NASA NTRS1982

Stacbeam - An efficient, low-mass, sequentially deployable structure

Design features of the stacking triangular articulated compact beam (Stacbeam) as a candidate truss structure for GEOS spacecraft solar power arrays are explored. Solar arrays of increasing size require folding, noninterfering structures, minimal thermal effects, slow and controlled deployment, and a high aspect ratio. The Stacbeam consists of a triangular batten frame perpendicular to the beam axis, three longerons attached at the corners of the batten frame and mounted parallel to the beam axis, and three diagonals to provide shear and torsional stiffness. Locking hinges are installed at the midpoint and ends of each longeron and at the midpoint and ends of each diagonal. The material is graphite/epoxy composite with a 120 GPa modulus and a 1500 kg/sq m density. Successful vertical deployment on the ground has been effected with a prototype deployer, together with horizontal cantilever in a fully deployed configuration.

Adams, L. R.↗
NASA NTRS1986

Lightweight, direct-radiating nickel hydrogen batteries

Two battery module configurations were developed which, in addition to integrating cylindrical nickel hydrogen (NiH2) cells into batteries, provide advances in the means of mounting, monitoring and thermal control of these cells. The main difference between the two modules is the physical arrangement of the cells: vertical versus horizontal. Direct thermal radiation to deep space is accomplished by substituting the battery structure for an exterior spacecraft panel. Unlike most conventional nickel-cadmium (NiCd) and NiH2 batteries, the cells are not tightly packed together; therefore ancillary heat conducting media to outside radiating areas, and spacecraft deck reinforcements for high mass concentration are not necessary. Testing included electrical characterization and a comprehensive regime of environmental exposures. The designs are flexible with respect to quantity and type of cells, orbit altitude and period, power demand profile, and the extent of cell parameter monitoring. This paper compares the characteristics of the two battery modules and summarizes their performance.

Metcalfe, J. R.↗
NASA NTRS1990

The Design of Optical Sensor for the Pinhole/Occulter Facility

Three optical sight sensor systems were designed, built and tested. Two optical lines of sight sensor system are capable of measuring the absolute pointing angle to the sun. The system is for use with the Pinhole/Occulter Facility (P/OF), a solar hard x ray experiment to be flown from Space Shuttle or Space Station. The sensor consists of a pinhole camera with two pairs of perpendicularly mounted linear photodiode arrays to detect the intensity distribution of the solar image produced by the pinhole, track and hold circuitry for data reduction, an analog to digital converter, and a microcomputer. The deflection of the image center is calculated from these data using an approximation for the solar image. A second system consists of a pinhole camera with a pair of perpendicularly mounted linear photodiode arrays, amplification circuitry, threshold detection circuitry, and a microcomputer board. The deflection of the image is calculated by knowing the position of each pixel of the photodiode array and merely counting the pixel numbers until threshold is surpassed. A third optical sensor system is capable of measuring the internal vibration of the P/OF between the mask and base. The system consists of a white light source, a mirror and a pair of perpendicularly mounted linear photodiode arrays to detect the intensity distribution of the solar image produced by the mirror, amplification circuitry, threshold detection circuitry, and a microcomputer board. The deflection of the image and hence the vibration of the structure is calculated by knowing the position of each pixel of the photodiode array and merely counting the pixel numbers until threshold is surpassed.

Greene, Michael E.↗
NASA NTRS1992

Active control of sound transmission through stiff lightweight composite fuselage constructions

Work was performed on the active control of sound transmission in composite structures. First, a model was outlined of a vibrating plate with arbitrary boundary conditions. Second, the far field was minimized to radiate acoustic power using secondary force inputs. Third, a model of a simple case of freely mounted stiff lightweight panels was used. Fourth, experimental results for aluminum honeycomb composite panels is presented. Fifth, experimental results are presented for the combination of a clamped steel plate and an aluminum honeycomb panel with secondary forces acting between the partitions. Finally, experimental results for the combination of a clamped steel plate with four secondary aluminum honeycomb panels is presented. All materials are shown in viewgraph format.

Thomas, D. R.↗
NASA NTRS1996

STS-74 Space Shuttle Mission Report

The STS-74 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-third flight of the Space Shuttle Program, the forty-eighth flight since the return-to-flight, and the fifteenth flight of the Orbiter Atlantis (OV-104). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-74; three Phase 11 SSME's that were designated as serial numbers 2012, 2026, and 2032 in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-076. The RSRM's, designated RSRM-51, were installed in each SRB and the individual RSRM's were designated as 360TO51 A for the left SRB, and 360TO51 B for the right SRB. The primary objectives of this flight were to rendezvous and dock with the Mir Space Station and perform life sciences investigations. The Russian Docking Module (DM) was berthed onto the Orbiter Docking System (ODS) using the Remote Manipulator System (RMS), and the Orbiter docked to the Mir with the DM. When separating from the Mir, the Orbiter undocked, leaving the DM attached to the Mir. The two solar arrays, mounted on the DM, were delivered for future Russian installation to the Mir. The secondary objectives of the flight were to perform the operations necessary to fulfill the requirements of the GLO experiment (GLO-4)/Photogrammetric Appendage Structural Dynamics Experiment Payload (PASDE) (GPP), the IMAX Cargo Bay Camera (ICBC), and the Shuttle Amateur Radio Experiment-2 (SAREX-2). Appendix A lists the sources of data, both formal and informal, that were used to prepare this report. Appendix B provides the definition of acronyms and abbreviations used throughout the report. All times during the flight are given in Greenwich mean time (GMT)) and mission elapsed time (MET).

Fricke, Robert W., Jr.↗
NASA NTRS1997

Optimal Configuration of an Array of Tabs for Mixing Enhancement in a Shear Layer

The large and small scale vortical motions produced by delta tabs in a two-stream shear layer have been studied experimentally. The tabs were placed at the trailing edge of a splitter plate, mounted in the test section of a wind tunnel, that produced the shear layer. Hot-wire measurements detailed the velocity, vorticity and small scale population distributions in the 3-D space behind the tabs. Small scale structures, which represent the peak in the dissipation spectrum, were identified and counted using the Peak-Valley-Counting technique. The optimal tab inclination angle, theta, and the optimal spanwise spacing, S, for a multiple tab array were identified. The optimal condition was that which maximized the small scale population and generated the strongest streamwise vorticity. Increasing the tab pitch angle from flush to normal to the splitter plate increased the streamwise vorticity as well as the overall small scale population. In fact, the increase in the overall small scale population correlated strongly with the increase in streamwise vorticity intensity. The optimal conditions for peak streamwise vorticity and peak small scale population, with minimum area blockage, were determined to be theta = 45deg and S = 1.5 tab widths.

Foss, J. K.↗
NASA NTRS2012

Modeling Programs Increase Aircraft Design Safety

Flutter may sound like a benign word when associated with a flag in a breeze, a butterfly, or seaweed in an ocean current. When used in the context of aerodynamics, however, it describes a highly dangerous, potentially deadly condition. Consider the case of the Lockheed L-188 Electra Turboprop, an airliner that first took to the skies in 1957. Two years later, an Electra plummeted to the ground en route from Houston to Dallas. Within another year, a second Electra crashed. In both cases, all crew and passengers died. Lockheed engineers were at a loss as to why the planes wings were tearing off in midair. For an answer, the company turned to NASA s Transonic Dynamics Tunnel (TDT) at Langley Research Center. At the time, the newly renovated wind tunnel offered engineers the capability of testing aeroelastic qualities in aircraft flying at transonic speeds near or just below the speed of sound. (Aeroelasticity is the interaction between aerodynamic forces and the structural dynamics of an aircraft or other structure.) Through round-the-clock testing in the TDT, NASA and industry researchers discovered the cause: flutter. Flutter occurs when aerodynamic forces acting on a wing cause it to vibrate. As the aircraft moves faster, certain conditions can cause that vibration to multiply and feed off itself, building to greater amplitudes until the flutter causes severe damage or even the destruction of the aircraft. Flutter can impact other structures as well. Famous film footage of the Tacoma Narrows Bridge in Washington in 1940 shows the main span of the bridge collapsing after strong winds generated powerful flutter forces. In the Electra s case, faulty engine mounts allowed a type of flutter known as whirl flutter, generated by the spinning propellers, to transfer to the wings, causing them to vibrate violently enough to tear off. Thanks to the NASA testing, Lockheed was able to correct the Electra s design flaws that led to the flutter conditions and return the aircraft to safe flight. Today, all aircraft must have a flutter boundary 15 percent beyond the aircraft s expected maximum speed to ensure that flutter conditions are not encountered in flight. NASA continues to support research in new aircraft designs to improve knowledge of aeroelasticity and flutter. Through platforms such as Dryden Flight Research Center s Active Aeroelastic Wing (AAW) research aircraft, the Agency researches methods for in-flight validation of predictions and for controlling and taking advantage of aeroelastic conditions to enhance aircraft performance.

Source record↗
NASA NTRS2013

Calibration of the Soft X-ray Telescopes (SXT) Onboard the ASTRO-H Satellite

ASTRO-H is an astrophysics satellite dedicated for non-dispersive X-ray spectroscopic study on selective celestial X-ray sources. Among the onboard instruments there are four Wolter-I X-ray mirrors of their reflectors' figure in conical approximation. Two of the four are soft X-ray mirrors, of which the energy range is from a few hundred eV to 15 keV. The focal point instruments will be a calorimeter (SXS) and a CCD camera (SXI), respectively. The mirrors were in quadrant configuration with photons being reflected consecutively in the primary and secondary stage before landing on the focal plane of 5.6 m away from the interface between the two stages. The reflectors of the mirror are made of heat-formed aluminum substrate of the thickness gauged of 152 m, 229 m, and 305 m of the alloy 5052 H-19, followed by epoxy replication on gold-sputtered smooth Pyrex cylindrical mandrels to acquire the X-ray reflective surface. The epoxy layer is 10 m nominal and surface gold layer of 0.2 m. Improvements on angular response over its predecessors, e.g. Astro-E1/Suzaku mirrors, come from error reduction on the figure, the roundness, and the grazing angle/radius mismatching of the reflecting surface, and tighter specs and mechanical strength on supporting structure to reduce the reflector positioning and the assembly errors. Each soft x-ray telescope (SXT), FM1 or FM2, were integrated from four independent quadrants of mirrors. The stray-light baffles, in quadrant configuration, were mounted onto the integrated mirror. Thermal control units were attached to the perimeter of the integrated mirror to keep the mirror within operating temperature in space. The completed instrument went through a series of optical alignment, thus made the quadrant images confocal and their optical axes in parallel to achieve highest throughput possible. Environmental tests were carried out, and optical quality of the telescopes has been confirmed. The optical and x-ray calibrations also include: angular resolution, effective area in the energy range of ~ 0.4 - 12keV, off-axis response, etc. Some of those are being carried out by our counterpart at JAXA/ISAS, Japan. We report the calibration results of the FM1 and FM2 that were obtained at Goddard Space Flight Center.

ASTRO-H Satellite↗
NASA NTRS2014

Optimization of a Lunar Pallet Lander Reinforcement Structure Using a Genetic Algorithm

In this paper, a unique system level spacecraft design optimization will be presented. A Genetic Algorithm is used to design the global pattern of the reinforcing structure, while a gradient routine is used to adequately stiffen the sub-structure. The system level structural design includes determining the optimal physical location (and number) of reinforcing beams of a lunar pallet lander deck structure. Design of the substructure includes determining placement of secondary stiffeners and the number of rivets required for assembly.. In this optimization, several considerations are taken into account. The primary objective was to raise the primary natural frequencies of the structure such that the Pallet Lander primary structure does not significantly couple with the launch vehicle. A secondary objective is to determine how to properly stiffen the reinforcing beams so that the beam web resists the shear buckling load imparted by the spacecraft components mounted to the pallet lander deck during launch and landing. A third objective is that the calculated stress does not exceed the allowable strength of the material. These design requirements must be met while, minimizing the overall mass of the spacecraft. The final paper will discuss how the optimization was implemented as well as the results. While driven by optimization algorithms, the primary purpose of this effort was to demonstrate the capability of genetic algorithms to enable design automation in the preliminary design cycle. By developing a routine that can automatically generate designs through the use of Finite Element Analysis, considerable design efficiencies, both in time and overall product, can be obtained over more traditional brute force design methods.

Burt, Adam↗
NASA NTRS2021

Europa Environmental Testing of Thermal Hardware for the Mapping Imaging Spectrometer for Europa (MISE) Instrument

The Europa Clipper spacecraft, scheduled for launch in June 2022, hosts a suite of instruments including the Mapping Imaging Spectrometer for Europa (MISE). MISE is a high-optical through-put pushbroom infrared imaging spectrometer that can collect measurements within Europa’s challenging radiation environment. It is externally mounted to the spacecraft and as a result is exposed to high radiation levels and cold temperatures. The instrument consists of a scan mirror assembly, an optical bench including a Dyson spectrometer and a telescope, and a structure that supports a cryocooler and a radiator. The cryocooler is used to actively cool the focal plane array and the spectrometer. The heat from the cryocooler is rejected through pyrolytic graphite sheet thermal straps to a honeycomb radiator. MISE will implement thermal hardware that will either not be used on other parts of the spacecraft or have a more extreme environment than the spacecraft. As a result, the MISE instrument performed numerous environmental tests on its thermal hardware. This paper discusses the results of the thermal cycling and radiation tests performed on the MISE thermal hardware including a Lockheed Martin Micro1-2 cryocooler, Pyrolytic graphite sheet thermal straps, Annealed pyrolytic graphite K-Core, Rosemount Platinum Resistance Thermometers, Tayco Kapton Thermofoil heaters, Dale Ohm resistors, and aluminum honeycomb and facesheets.

Strong, Patrick↗