Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Trade Study”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Updated solid-core nuclear thermal propulsion engine trades

This study examined the application of state-of-the-art propulsion and reactor technologies to a near-term solid-core NERVA-based nuclear thermal propulsion system. Updated reactor performance and weight scaling laws were initially derived and input into a nuclear rocket engine system cycle design analysis code. Nuclear Thermal Propulsion (NTP) engine system weight, size, and performance are presented here for a large range of chamber pressures, nozzle area ratios, and thrust levels for three reactor fuel types operating at their corresponding temperatures. Operational characteristics and design features of representative NTP engine concepts are also presented.

Pelaccio, Dennis G.↗
NASA NTRS2007

Overview of Key Saturn Probe Mission Trades

Ongoing studies, performed at NASA/JPL over the past two years in support of NASA's SSE Roadmap activities, proved the feasibility of a NF class Saturn probe mission. I. This proposed mission could also provide a good opportunity for international collaboration with the proposed Cosmic Vision KRONOS mission: a) With ESA contributed probes (descent modules) on a NASA lead mission; b) Early 2017 launch could be a good programmatic option for ESA-CV/NASA-NF. II. A number of mission architectures could be suitable for this mission: a) Probe Relay based architecture with short flight time (approx. 6.3-7 years); b) DTE probe telecom based architecture with long flight time (-11 years), and low probe data rate, but with the probes decoupled from the carrier, allowing for polar trajectories I orbiter. This option may need technology development for telecom; c) Orbiter would likely impact mission cost over flyby, but would provide significantly higher science return. The Saturn probes mission is expected to be identified in NASA's New Frontiers AO. Thus, further studies are recommended to refine the most suitable architecture. International collaboration is started through the KRONOS proposal work; further collaborated studies will follow once KRONOS is selected in October under ESA's Cosmic Vision Program.

probes↗
NASA NTRS1989

Large Deployable Reflector (LDR) system concept and technology definition study. Volume 1: Executive summary, analyses and trades, and system concepts

A study was conducted to define reasonable and representative large deployable reflector (LDR) system concepts for the purpose of defining a technology development program aimed at providing the requisite technological capability necessary to start LDR development by the end of 1991. This volume includes the executive summary for the total study, a report of thirteen system analysis and trades tasks (optical configuration, aperture size, reflector material, segmented mirror, optical subsystem, thermal, pointing and control, transportation to orbit, structures, contamination control, orbital parameters, orbital environment, and spacecraft functions), and descriptions of three selected LDR system concepts. Supporting information is contained in appendices.

Agnew, Donald L.↗
NASA NTRS1993

Risk management for the Space Exploration Initiative

Probabilistic Risk Assessment (PRA) is a quantitative engineering process that provides the analytic structure and decision-making framework for total programmatic risk management. Ideally, it is initiated in the conceptual design phase and used throughout the program life cycle. Although PRA was developed for assessment of safety, reliability, and availability risk, it has far greater application. Throughout the design phase, PRA can guide trade-off studies among system performance, safety, reliability, cost, and schedule. These studies are based on the assessment of the risk of meeting each parameter goal, with full consideration of the uncertainties. Quantitative trade-off studies are essential, but without full identification, propagation, and display of uncertainties, poor decisions may result. PRA also can focus attention on risk drivers in situations where risk is too high. For example, if safety risk is unacceptable, the PRA prioritizes the risk contributors to guide the use of resources for risk mitigation. PRA is used in the Space Exploration Initiative (SEI) Program. To meet the stringent requirements of the SEI mission, within strict budgetary constraints, the PRA structure supports informed and traceable decision-making. This paper briefly describes the SEI PRA process.

Buchbinder, Ben↗
NASA NTRS1984

Advanced turbocharger design study program

The advanced Turbocharger Design Study consisted of: (1) the evaluation of three advanced engine designs to determine their turbocharging requirements, and of technologies applicable to advanced turbocharger designs; (2) trade-off studies to define a turbocharger conceptual design and select the engine with the most representative requirements for turbocharging; (3) the preparation of a turbocharger conceptual design for the Curtiss Wright RC2-32 engine selected in the trade-off studies; and (4) the assessment of market impact and the preparation of a technology demonstration plan for the advanced turbocharger.

Culy, D. G.↗
NASA NTRS2019

Development Concepts for Mars Ascent Vehicle (MAV) Solid and Hybrid Vehicle Systems

The Advanced Concepts Office (ACO) at Marshall Space Flight Center (MSFC) has conducted ongoing studies and trades into options for both hybrid and solid vehicle systems for potential Mars Ascent Vehicle (MAV) concepts for the Jet Propulsion Laboratory (JPL). Two MAV propulsion options are being studied for use in a potential Mars Sample Retrieval (MSR) campaign. The following paper describes the current concepts for hybrid and solid propulsion vehicles for MAV as part of a potential MSR campaign, and provides an overview of the ongoing studies and trades for both hybrid and solid vehicle system concepts. Concepts and options under consideration for vehicle subsystems include reaction control system (RCS), separation, and structures will be described in terms of technology readiness level (TRL), benefit to the vehicle design, and associated risk. A hybrid propulsion system, which uses a solid fuel core and liquid oxidizer, is currently being developed by JPL with support from MSFC. This type of hybrid propulsion vehicle would allow the MAV to be more flexible at the cost of higher complexity, in contrast to the solid propulsion vehicle that is simpler, but allows less flexibility. The solid propulsion vehicle study performed by MSFC in 2018 further refined the solid propulsion system sizing as well as added definition to vehicle subsystem concepts, including the RCS, structures and configuration, interstage and separation, aerodynamics, and power/avionics. The studies were performed using an iterative concept design methodology, engaging subject matter experts from across MSFC’s propulsion and vehicle systems disciplines as well as seeking trajectory feedback from analysts at JPL.

McCollum, Lisa Tunstill↗
NASA NTRS1988

Configuration trade and code validation study on a conical hypersonic vehicle

A study has been conducted on a generic wing-cone transatmospheric vehicle at Mach numbers form 2.5 to 4.5. The objectives of the study were to experimentally define the aerodynamic characteristics of the vehicle and evaluate several computational aerodynamic prediction methods through comparison with the experimental results. The baseline wing-cone configuration fuselage consisted of a 5 deg half-angle cone forebody, cylindrical midbody, and 9 deg truncated cone afterbody. The 4-percent-thick diamond airfoil wing had an aspect ratio of 1. Several configuration variables were investigated to provide trade information on canard, wing-position and incidence, vertical tail, and nose bluntness effects. Results of the study show that wing-position and wing-incidence effects on the longitudinal aerodynamic characteristics can be significantly influenced by wing-body interference. The use of positive wing incidence to provide favorable forebody orientation for possible inlet performance improvement is accompanied by trim drag and lift-drag ratio penalties. The lateral-directional stability characteristics were strongly influenced by the location of the vertical tails. The higher-order full-potential method provided better estimates of the aerodynamic characteristics than either the linearized supersonic potential method or the tangent-cone/tangent-wedge/shock-expansion on method.

Covell, Peter F.↗
NASA NTRS2003

Evaluation of a Singular Value Decomposition Approach for Impact Dynamic Data Correlation

Impact dynamic tests are used in the automobile and aircraft industries to assess survivability of occupants during crash, to assert adequacy of the design, and to gain federal certification. Although there is no substitute for experimental tests, analytical models are often developed and used to study alternate test conditions, to conduct trade-off studies, and to improve designs. To validate results from analytical predictions, test and analysis results must be compared to determine the model adequacy. The mathematical approach evaluated in this paper decomposes observed time responses into dominant deformation shapes and their corresponding contribution to the measured response. To correlate results, orthogonality of test and analysis shapes is used as a criterion. Data from an impact test of a composite fuselage is used and compared to finite element predictions. In this example, the impact response was decomposed into multiple shapes but only two dominant shapes explained over 85% of the measured response

Horta, Lucas G.↗
NASA NTRS1989

Analysis of an algae-based CELSS. I - Model development

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food, O2, the recycle of human waste and trash, H2O, N2, and food production/supply. A simple noniterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.

Holtzapple, Mark T.↗
NASA NTRS1989

Analysis of an algae-based CELSS. Part 1: model development

A steady state chemical model and computer program have been developed for a life support system and applied to trade-off studies. The model is based on human demand for food and oxygen determined from crew metabolic needs. The model includes modules for water recycle, waste treatment, CO2 removal and treatment, and food production. The computer program calculates rates of use and material balance for food. O2, the recycle of human waste and trash, H2O, N2, and food production supply. A simple non-iterative solution for the model has been developed using the steady state rate equations for the chemical reactions. The model and program have been used in system sizing and subsystem trade-off studies of a partially closed life support system.

Models, Chemical↗
NASA NTRS1977

Design study of superconducting magnets for a combustion magnetohydrodynamic (MHD) generator

Design trade off studies for 13 different superconducting magnet systems were carried out. Based on these results, preliminary design characteristics were prepared for several superconducting magnet systems suitable for use with a combustion driven MHD generator. Each magnet generates a field level of 8 T in a volume 1.524 m (60 in.) long with a cross section 0.254 m x 0.254 m (10 in. x 10 in.) at the inlet and 0.406 m x .406 m (16 in. x 16 in.) at the outlet. The first design involves a racetrack coil geometry intended for operation at 4.2 K; the second design uses a racetrack geometry at 2.0 K; and the third design utilizes a rectangular saddle geometry at 4.2 K. Each case was oriented differently in terms of MHD channel axis and main field direction relative to gravity in order to evaluate fabrication ease. All cases were designed such that the system could be disassembled to allow for alteration of field gradient in the MHD channel by changing the angle between coils. Preliminary design characteristics and assembly drawings were generated for each case.

Thome, R. J.↗
DOE OSTI2020

Evaluating Trade-offs in Potential Exascale Interconnect Technologies

This report details work to study trade-offs in topology and network bandwidth for potential interconnects in the exascale (2021-2022) timeframe. The work was done using multiple interconnect models across two parallel discrete event simulators. Results from each independent simulator are shown and discussed and the areas of agreement and disagreement are explored.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1980

Propulsion Study for Small Transport Aircraft Technology (STAT)

Propulsion requirements were determined for 0.5 and 0.7 Mach aircraft. Sensitivity studies were conducted on both these aircraft to determine parametrically the influence of propulsion characteristics on aircraft size and direct operating cost (DOC). Candidate technology elements and design features were identified and parametric studies conducted to select the STAT advanced engine cycle. Trade off studies were conducted to determine those advanced technologies and design features that would offer a reduction in DOC for operation of the STAT engines. These features were incorporated in the two STAT engines. A benefit assessment was conducted comparing the STAT engines to current technology engines of the same power and to 1985 derivatives of the current technology engines. Research and development programs were recommended as part of an overall technology development plan to ensure that full commercial development of the STAT engines could be initiated in 1988.

Gill, J. C.↗
NASA NTRS1982

Advanced hybrid vehicle propulsion system study

Results are presented of a study of an advanced heat engine/electric automotive hybrid propulsion system. The system uses a rotary stratified charge engine and ac motor/controller in a parallel hybrid configuration. The three tasks of the study were (1) parametric studies involving five different vehicle types, (2) design trade-off studies to determine the influence of various vehicle and propulsion system paramaters on system performance fuel economy and cost, and (3) a conceptual design establishing feasibility at the selected approach. Energy consumption for the selected system was .034 1/km (61.3 mpg) for the heat engine and .221 kWh/km (.356 kWh/mi) for the electric power system over a modified J227 a schedule D driving cycle. Life cycle costs were 7.13 cents/km (11.5 cents/mi) at $2/gal gasoline and 7 cents/kWh electricity for 160,000 km (100,000 mi) life.

Schwarz, R.↗
NASA NTRS1972

Scientific Instrument Package for the large space telescope (SIP)

The feasibility of a scientific instrument package (SIP) that will satisfy the requirements of the large space telescope was established. A reference configuration serving as a study model and data which will aid in the trade-off studies leading to the final design configuration are reported.

Source record↗
NASA NTRS1981

Predesign study for a modern 4-bladed rotor for the NASA rotor systems research aircraft

Trade-off study results and the rationale for the final selection of an existing modern four-bladed rotor system that can be adapted for installation on the Rotor Systems Research Aircraft (RSRA) are reported. The results of the detailed integration studies, parameter change studies, and instrumentation studies and the recommended plan for development and qualification of the rotor system is also given. Its parameter variants, integration on the RSRA, and support of ground and flight test programs are also discussed.

Bishop, H. E.↗