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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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NASA NTRS2008

System Engineering for J-2X Development: The Simpler, the Better

The Ares I and Ares V Vehicles will utilize the J-2X rocket engine developed for NASA by the Pratt and Whitney Rocketdyne Company (PWR) as the upper stage engine (USE). The J-2X is an improved higher power version of the original J-2 engine used for Apollo. System Engineering (SE) facilitates direct and open discussions of issues and problems. This simple idea is often overlooked in large, complex engineering development programs. Definition and distribution of requirements from the engine level to the component level is controlled by Allocation Reports which breaks down numerical design objectives (weight, reliability, etc.) into quanta goals for each component area. Linked databases of design and verification requirements help eliminate redundancy and potential mistakes inherent in separated systems. Another tool, the Architecture Design Description (ADD), is used to control J-2X system architecture and effectively communicate configuration changes to those involved in the design process. But the proof of an effective process is in successful program accomplishment. SE is the methodology being used to meet the challenge of completing J-2X engine certification 2 years ahead of any engine program ever developed at PWR. This paper describes the simple, better SE tools and techniques used to achieve this success.

Kelly, William M.↗
NASA NTRS2008

24-Way Radial Power Combiner/Divider for 31 to 36 GHz

The figure shows a prototype radial power-combining waveguide structure, capable of operation at frequencies from 31 to 36 GHz, that features an unusually large number (N = 24) of combining (input) ports. The combination of wide-band operation and large N is achieved by incorporating several enhancements over a basic radial power-combiner design. In addition, the structure can be operated as a power divider by reversing the roles of the input and output ports. In this structure, full-height waveguides at the combining ports are matched in impedance to reduced-height radial waveguides inside the combiner base. This match is effected by impedance-transforming stepped waveguide sections. This matching scheme is essential to achievement of large N because N is limited by the height of the waveguides in the base. Power is coupled from the 24 reduced- height radial waveguides into the TE01 mode of a circular waveguide in the base with the help of a matching post at the bottom of the base. ( TE signifies transverse electric, the first subscript is the azimuthal mode number, and the second subscript is the radial mode number.) More specifically, the matching post matches the reflections from the walls of the 24 reduced-height waveguides and enables the base design to exceed the bandwidth requirement. After propagating along the circular waveguide, the combined power is coupled, via a mode transducer, to a rectangular waveguide output port. The mode transducer is divided into three sections, each sized and shaped as part of an overall design to satisfy the mode-conversion and output-coupling requirements while enabling the circular waveguide to be wide enough for combining the 24 inputs over the frequency range of 31 to 36 GHz. During the design process, it was found that two different rectangular waveguide outputs could be accommodated through modification of only the first section of the mode converter, thereby enabling operation in multiple frequency ranges.

Epp, Larry↗
NASA NTRS2009

Ares I Static Tests Design

Probabilistic engineering design enhances safety and reduces costs by incorporating risk assessment directly into the design process. In this paper, we assess the format of the quantitative metrics for the vehicle which will replace the Space Shuttle, the Ares I rocket. Specifically, we address the metrics for in-flight measurement error in the vector position of the motor nozzle, dictated by limits on guidance, navigation, and control systems. Analyses include the propagation of error from measured to derived parameters, the time-series of dwell points for the duty cycle during static tests, and commanded versus achieved yaw angle during tests. Based on these analyses, we recommend a probabilistic template for specifying the maximum error in angular displacement and radial offset for the nozzle-position vector. Criteria for evaluating individual tests and risky decisions also are developed.

Carson, William↗
NASA NTRS2007

Cryogenic Pressure Control Modeling for Ellipsoidal Space Tanks

A computational fluid dynamics (CFD) model is developed to simulate pressure control of an ellipsoidal-shaped liquid hydrogen tank under external heating in normal gravity. Pressure control is provided by an axial jet thermodynamic vent system (TVS) centered within the vessel that injects cooler liquid into the tank, mixing the contents and reducing tank pressure. The two-phase cryogenic tank model considers liquid hydrogen in its own vapor with liquid density varying with temperature only and a fully compressible ullage. The axisymmetric model is developed using a custom version of the commercially available FLOW-31) software. Quantitative model validation is ,provided by engineering checkout tests performed at Marshall Space Flight Center in 1999 in support of the Solar Thermal Upper Stage_ Technology Demonstrator (STUSTD) program. The engineering checkout tests provide cryogenic tank self-pressurization test data at various heat leaks and tank fill levels. The predicted self-pressurization rates, ullage and liquid temperatures at discrete locations within the STUSTD tank are in good agreement with test data. The work presented here advances current CFD modeling capabilities for cryogenic pressure control and helps develop a low cost CFD-based design process for space hardware.

Lopez, Alfredo↗
NASA NTRS2007

Spiral Orbit Tribometer

The spiral orbit tribometer (SOT) bridges the gap between full-scale life testing and typically unrealistic accelerated life testing of ball-bearing lubricants in conjunction with bearing ball and race materials. The SOT operates under realistic conditions and quickly produces results, thereby providing information that can guide the selection of lubricant, ball, and race materials early in a design process. The SOT is based upon a simplified, retainerless thrust bearing comprising one ball between flat races (see figure). The SOT measures lubricant consumption and degradation rates and friction coefficients in boundary lubricated rolling and pivoting contacts. The ball is pressed between the lower and upper races with a controlled force and the lower plate is rotated. The combination of load and rotation causes the ball to move in a nearly circular orbit that is, more precisely, an opening spiral. The spiral s pitch is directly related to the friction coefficient. At the end of the orbit, the ball contacts the guide plate, restoring the orbit to its original radius. The orbit is repeatable throughout the entire test. A force transducer, mounted in-line with the guide plate, measures the force between the ball and the guide plate, which directly relates to the friction coefficient. The SOT, shown in the figure, can operate in under ultra-high vacuum (10(exp -9) Torr) or in a variety of gases at atmospheric pressure. The load force can be adjusted between 45 and 450 N. By varying the load force and ball diameter, mean Hertzian stresses between 0.5 and 5.0 GPa can be obtained. The ball s orbital speed range is between 1 and 100 rpm.

Pepper, Stephen V.↗
NASA NTRS2009

Noise Control in Space Shuttle Orbiter

Acoustic limits in habitable space enclosures are required to ensure crew safety, comfort, and habitability. Noise control is implemented to ensure compliance with the acoustic requirements. The purpose of this paper is to describe problems with establishing acoustic requirements and noise control efforts, and present examples of noise control treatments and design applications used in the Space Shuttle Orbiter. Included is the need to implement the design discipline of acoustics early in the design process, and noise control throughout a program to ensure that limits are met. The use of dedicated personnel to provide expertise and oversight of acoustic requirements and noise control implementation has shown to be of value in the Space Shuttle Orbiter program. It is concluded that to achieve acceptable and safe noise levels in the crew habitable space, early resolution of acoustic requirements and implementation of effective noise control efforts are needed. Management support of established acoustic requirements and noise control efforts is essential.

Goodman, Jerry R.↗
NASA NTRS2010

Boom-Constrained Drag Minimization for Design of Supersonic Concepts

This paper presents an approach to modifying an existing baseline configuration that has been designed to achieve low-boom characteristics in order to minimize drag while not severely penalizing baseline sonic boom levels. The baseline configuration that was used is the result of using a mixed-fidelity CFD-based low-boom design process that has been tested and verified. Shape modifications are carried out by using arbitrary shape-deformation algorithms. The focus of this paper is the integration of several key enabling techniques and methods for efficient redesign under stringent constraints.

Rallabhandi, Sriram K.↗
NASA NTRS2010

ENRE 655 Class Project. Development of the Initial Main Parachute Failure Probability for the Constellation Program (CxP) Orion Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS)

Loss of Crew (LOC) and Loss of Mission (LOM) are two key requirements the Constellation Program (CxP) measure against. To date, one of the top risk drivers for both LOC and LOM has been Orion's Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS). Even though the Orion CPAS is one of the top risk drivers of CxP, it has been very difficult to obtain any relevant data to accurately quantify the risk. At first glance, it would seem that a parachute system would be very reliable given the track record of Apollo and Soyuz. Given the success of those two programs, the amount of data is considered to be statistically insignificant. However, due to CxP having LOC/LOM as key design requirements, it was necessary for Orion to generate a valid prior to begin the Risk Informed Design process. To do so, the Safety & Mission Assurance (S&MA) Space Shuttle & Exploration Analysis Section generated an initial failure probability for Orion to use in preparation for the Orion Systems Requirements Review (SRR).

Fuqua, Bryan C.↗
NASA NTRS2010

PRA in Design: Increasing Confidence in Pre-Operational Assessments of Risks (Results of a Joint NASA/NRC Workshop)

In late 2009, the National Aeronautics and Space Administration (NASA) and the U.S. Nuclear Regulatory Commission (NRC) jointly organized a workshop to discuss technical issues associated with application of risk assessments to early phases of system design. The workshop, which was coordinated by the Idaho National Laboratory, involved invited presentations from a number of PRA experts in the aerospace and nuclear fields and subsequent discussion to address the following questions: (a) What technical issues limit decision-makers' confidence in PRA results, especially at a pre-operational phase of the system life cycle? (b) What is being done to address these issues'? (c) What more can be done ? The workshop resulted in participant observations and suggestions on several technical issues, including the pursuit of non-traditional approaches to risk assessment and the verification and validation of risk models. The workshop participants also identified several important non-technical issues, including risk communication with decision makers, and the integration of PRA into the overall design process.

Youngblood, Robert↗
NASA NTRS2010

Concept, Design, and Prototyping of XSAS: A High Power Extendable Solar Array for CubeSat Applications

CubeSats have proven themselves as a reliable and cost-effective method to perform experiments in space, but they are highly constrained by their specifications and size. One such constraint is the average continuous power, about 5 W, which is available to the typical CubeSat. To improve this constraint, we have developed the eXtendable Solar Array System (XSAS), a deployable solar array prototype in a CubeSat package, which can provide an average 23 W of continuous power. The prototype served as a technology demonstrator for the high risk mechanisms needed to release, deploy, and control the solar array. Aside from this drastic power increase, it is in the integration of each mechanism, their application within the small CubeSat form-factor, and the inherent passive control benefit of the deployed geometry that make XSAS a novel design. In this paper, we discuss the requirements and design process for the XSAS system and mechanical prototype, and provide qualitative and quantitative results from numerical simulations and prototype tests. We also discuss future work, including an upcoming NASA zero-gravity flight campaign, to further improve on XSAS and prepare it for future launch opportunities.

Senatore, Patrick↗
NASA NTRS2010

Design of a Slowed-Rotor Compound Helicopter for Future Joint Service Missions

A slowed-rotor compound helicopter has been synthesized using the NASA Design and Analysis of Rotorcraft (NDARC) conceptual design software. An overview of the design process and the capabilities of NDARC are presented. The benefits of trading rotor speed, wing-rotor lift share, and trim strategies are presented for an example set of sizing conditions and missions.

Silva, Christopher↗
NASA NTRS2010

Use of Modal Acoustic Emission to Monitor Damage Progression in Carbon Fiber/Epoxy Tows and Implications for Composite Structures

This slide presentation reviews the use of Modal Acoustic Emission to monitor damage progression to carbon fiber/epoxy tows. There is a risk for catastrophic failure of composite overwrapped pressure vessels (COPVs) due to burst-before-leak (BBL) stress rupture (SR) failure of carbon-epoxy (C/Ep) COPVs. A lack of quantitative nondestructive evaluation (NDE) is causing problems in current and future spacecraft designs. It is therefore important to develop and demonstrate critical NDE that can be implemented during stages of the design process since the observed rupture can occur with little of no advanced warning. Therefore a program was required to develop quantitative acoustic emission (AE) procedures specific to C/Ep overwraps, but which also have utility for monitoring damage accumulation in composite structure in general, and to lay the groundwork for establishing critical thresholds for accumulated damage in composite structures, such as COPVs, so that precautionary or preemptive engineering steps can be implemented to minimize of obviate the risk of catastrophic failure. A computed Felicity Ratio (FR) coupled with fast Fourier Transform (FFT) frequency analysis shows promise as an analytical pass/fail criterion. The FR analysis and waveform and FFT analysis are reviewed

Waller, Jess M.↗
NASA NTRS2010

Optical Design for the Submillimeter and Far InfraRed Experiment (SAFIRE)

The SAFIRE, the Submillimeter and Far InfraRed Experiment, was designed for interstellar physics in the airborne Observatory SOFIA. SAFIRE is a cryogenic Echelle Grating spectrograph for covering 27 to 470 microns; with R ranging from 2-6,000. Here we will discuss the details of the optical design, the design process, and the performance of the instrument

Pasquale, Bert A.↗
NASA NTRS2010

Optical Design for the Composite InfraRed Spectrometer Lite (CIRS-Lite)

Following up on Cassini/CIRS, we are building the next-generation Composite InfraRed Spectrometer for deep-space planetary exploration. CIRS-Lite combines Mid & Far-IR channels into a single instrument with 4x the spectral sensitivity of CIRS. Here we discuss the instrument optical design, the design process, and the system performance.

Pasquale, Bert A.↗
NASA NTRS1999

Technology Integration (Task 20) Aeroservoelastic Modeling and Design Studies: Evaluation of Aeroservoelastic Effects on Flutter and Dynamic Gust Response - Part A

The HSCT Flight Controls Group has developed longitudinal control laws, utilizing PTC aeroelastic flexible models to minimize aeroservoelastic interaction effects, for a number of flight conditions. The control law design process resulted in a higher order controller and utilized a large number of sensors distributed along the body for minimizing the flexibility effects. Processes were developed to implement these higher order control laws for performing the dynamic gust loads and flutter analyses. The processes and its validation were documented in Reference 2, for selected flight condition. The analytical results for additional flight conditions are presented in this document for further validation.

Nagaraja, K. S.↗
NASA NTRS2001

Humanoids Designed to do Work

NASA began with the challenge of building a robot fo r doing assembly, maintenance, and diagnostic work in the Og environment of space. A robot with human form was then chosen as the best means of achieving that mission. The goal was not to build a machine to look like a human, but rather, to build a system that could do the same work. Robonaut could be inserted into the existing space environment, designed for a population of astronauts, and be able to perform many of the same tasks, with the same tools, and use the same interfaces. Rather than change that world to accommodate the robot, instead Robonaut accepts that it exists for humans, and must conform to it. While it would be easier to build a robot if all the interfaces could be changed, this is not the reality of space at present, where NASA has invested billions of dollars building spacecraft like the Space Shuttle and International Space Station. It is not possible to go back in time, and redesign those systems to accommodate full automation, but a robot can be built that adapts to them. This paper describes that design process, and the res ultant solution, that NASA has named Robonaut.

Ambrose, Robert↗
NASA NTRS2010

Risk Evaluation in the Pre-Phase A Conceptual Design of Spacecraft

Typically, the most important decisions in the design of a spacecraft are made in the earliest stages of its conceptual design the Pre-Phase A stages. It is in these stages that the greatest number of design alternatives is considered, and the greatest number of alternatives is rejected. The focus of Pre-Phase A conceptual development is on the evaluation and comparison of whole concepts and the larger-scale systems comprising those concepts. This comparison typically uses general Figures of Merit (FOMs) to quantify the comparative benefits of designs and alternative design features. Along with mass, performance, and cost, risk should be one of the major FOMs in evaluating design decisions during the conceptual design phases. However, risk is often given inadequate consideration in conceptual design practice. The reasons frequently given for this lack of attention to risk include: inadequate mission definition, lack of rigorous design requirements in early concept phases, lack of fidelity in risk assessment methods, and under-evaluation of risk as a viable FOM for design evaluation. In this paper, the role of risk evaluation in early conceptual design is discussed. The various requirements of a viable risk evaluation tool at the Pre-Phase A level are considered in light of the needs of a typical spacecraft design study. A technique for risk identification and evaluation is presented. The application of the risk identification and evaluation approach to the conceptual design process is discussed. Finally, a computational tool for risk profiling is presented and applied to assess the risk for an existing Pre-Phase A proposal. The resulting profile is compared to the risks identified for the proposal by other means.

Fabisinski, Leo L., III↗
NASA NTRS2010

NASA's Applied Sciences: Natural Disasters Program

Fully utilize current and near-term airborne and spaceborne assets and capabilities. NASA spaceborne instruments are for research but can be applied to natural disaster response as appropriate. NASA airborne instruments can be targeted specifically for disaster response. Could impact research programs. Better flow of information improves disaster response. Catalog capability, product, applicable disaster, points of contact. Ownership needs to come from the highest level of NASA - unpredictable and irregular nature of disasters requires contingency funding for disaster response. Build-in transfer of applicable natural disaster research capabilities to operational functionality at other agencies (e.g., USFS, NOAA, FEMA...) at the outset, whenever possible. For the Decadal Survey Missions, opportunities exist to identify needs and requirements early in the mission design process. Need to understand additional needs and commitments for meeting the needs of the disaster community. Opportunity to maximize disaster response and mitigation from the Decadal Survey Missions. Additional needs or capabilities may require agency contributions.

Kessler, Jason L.↗