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At least 649 records · Page 36

High-Pressure Hot-Gas Self-Acting Floating Ring Shaft Seal for Liquid Rocket Turbopumps

Design analysis, detail design, fabrication, and experimental evaluation was performed on two self acting floating ring shaft seals for a rocket engine turbopump high pressure 24132500 n/sq m (3500 psig) hot gas 533 K 9500 F) high speed 3142 rad/sec (30000 rmp) turbine. The initial design used Rayleigh step hydrodynamic lift pads to assist in centering the seal ring with minimum rubbing contact. The final design used a convergent tapered bore to provide hydrostatic centering force. The Rayleigh step design was tested for 107 starts and 4.52 hours total. The leakage was satisfactory; however, the design was not acceptable due to excessive wear caused by inadequate centering force and failure of the sealing dam caused by erosion damage. The tapered bore design was tested for 370 starts and 15.93 hours total. Satisfactory performance for the required life of 7.5 hours per seal was successfully demonstrated.

Burcham, R. E.↗

Spray momentum measuring system

Technique enables accurate prediction of erosion and cavitation produced by fluid spray. Method measures high velocity sprays produced by small orifices. Originally designed to determine oxidizer-injection patterns of liquid fueled rocket engines, technique is used with other liquids, or, with appropriate modification, with gases.

Sheffield, E. W.↗

Cryogenic gel flow viscometer

Coiled section of tubing measures viscous properties of gelled cryogenic propellants under conditions closely resembling flow in rocket engine systems. Characteristic flow curve provides data necessary for the design of prototype hardware systems using the liquid or gel of interest.

Globus, R. H.↗

The future look in rocket engines

The Space Shuttle Main Engine and an Aerospike engine for the Space Tug illustrate the rocket engines of the future. This paper includes a description of design features leading to high performance, long life, and low cost. Computer control of the engine, turnaround maintenance plans, and engine development plans are also discussed.

Sanchini, D. J.↗

The space transportation system

Design features of the Space Shuttle orbiter vehicle, main engine, solid rocket booster, external tank, and inertial and spinning solid upper stages are presented. Space Shuttle facilities at Kennedy Space Center are discussed, together with the long duration exposure facility, a reusable, unmanned gravity-gradient stabilized, free-flying structure which can accomodate both active and passive experiments requiring long-term space exposure. Standard and optional Shuttle services are outlined, and preliminary flight assignments are described.

Hamon, W. J.↗

Updating Gimbal Actuators for the Long Journey to Saturn

The Cassini mission requires extraordinary life and reliability from the linear servo-actuators which position the spacecraft's redundant rocket engines. Both commercial actuators and existing in-house actuator designs were studied for this application. Ultimately a device inherited from JPL's Mariner and Viking missions to Mars was selected because of its close match to functional requirements and its flight pedigree. However, several design improvements were necessary to meet life and reliability goals. Special attention was focused on reliability testing of the motor and mechanism at all stages of procurement and assembly because a brush type of DC motor was retained from the old design. These improvements and, in particular, efforts to develop new component sources are discussed in this paper.

Iskenderian, Theodore↗

Modular Rocket Engine Control Software (MRECS)

The Modular Rocket Engine Control Software (MRECS) Program is a technology demonstration effort designed to advance the state-of-the-art in launch vehicle propulsion systems. Its emphasis is on developing and demonstrating a modular software architecture for advanced engine control systems that will result in lower software maintenance (operations) costs. It effectively accommodates software requirement changes that occur due to hardware technology upgrades and engine development testing. Ground rules directed by MSFC were to optimize modularity and implement the software in the Ada programming language. MRECS system software and the software development environment utilize Commercial-Off-the-Shelf (COTS) products. This paper presents the objectives, benefits, and status of the program. The software architecture, design, and development environment are described. MRECS tasks are defined and timing relationships given. Major accomplishments are listed. MRECS offers benefits to a wide variety of advanced technology programs in the areas of modular software architecture, reuse software, and reduced software reverification time related to software changes. MRECS was recently modified to support a Space Shuttle Main Engine (SSME) hot-fire test. Cold Flow and Flight Readiness Testing were completed before the test was cancelled. Currently, the program is focused on supporting NASA MSFC in accomplishing development testing of the Fastrac Engine, part of NASA's Low Cost Technologies (LCT) Program. MRECS will be used for all engine development testing.

Tarrant, C.↗

Bantam: A Systematic Approach to Reusable Launch Vehicle Technology Development

The Bantam technology project is focused on providing a low cost launch capability for very small (100 kilogram) NASA and University science payloads. The cost goal has been set at one million dollars per launch. The Bantam project, however, represents much more than a small payload launch capability. Bantam represents a unique, systematic approach to reusable launch vehicle technology development. This technology maturation approach will enable future highly reusable launch concepts in any payload class. These launch vehicle concepts of the future could deliver payloads for hundreds of dollars per pound, enabling dramatic growth in civil and commercial space enterprise. The National Aeronautics and Space Administration (NASA) has demonstrated a better, faster, and cheaper approach to science discovery in recent years. This approach is exemplified by the successful Mars Exploration Program lead by the Jet Propulsion Laboratory (JPL) for the NASA Space Science Enterprise. The Bantam project represents an approach to space transportation technology maturation that is very similar to the Mars Exploration Program. The NASA Advanced Space Transportation Program (ASTP) and Future X Pathfinder Program will combine to systematically mature reusable space transportation technology from low technology readiness to system level flight demonstration. New reusable space transportation capability will be demonstrated at a small (Bantam) scale approximately every two years. Each flight demonstration will build on the knowledge derived from the previous flight tests. The Bantam scale flight demonstrations will begin with the flights of the X-34. The X-34 will demonstrate reusable launch vehicle technologies including; flight regimes up to Mach 8 and 250,000 feet, autonomous flight operations, all weather operations, twenty-five flights in one year with a surge capability of two flights in less than twenty-four hours and safe abort. The Bantam project will build on this initial capability to expand the capability of a reusable first stage, including ground launch, powered return to the launch site, and a fully reusable rocket propulsion system. A Bantam technology goal is to demonstrate twenty-five flights with no unplanned rocket engine maintenance and only minor planned maintenance or inspections. The design goal of the propulsion system is a mission life of one hundred.

Griner, Carolyn↗

Modular Rocket Engine Control Software (MRECS)

The Modular Rocket Engine Control Software (MRECS) Program is a technology demonstration effort designed to advance the state-of-the-art in launch vehicle propulsion systems. Its emphasis is on developing and demonstrating a modular software architecture for a generic, advanced engine control system that will result in lower software maintenance (operations) costs. It effectively accommodates software requirements changes that occur due to hardware. technology upgrades and engine development testing. Ground rules directed by MSFC were to optimize modularity and implement the software in the Ada programming language. MRECS system software and the software development environment utilize Commercial-Off-the-Shelf (COTS) products. This paper presents the objectives and benefits of the program. The software architecture, design, and development environment are described. MRECS tasks are defined and timing relationships given. Major accomplishment are listed. MRECS offers benefits to a wide variety of advanced technology programs in the areas of modular software, architecture, reuse software, and reduced software reverification time related to software changes. Currently, the program is focused on supporting MSFC in accomplishing a Space Shuttle Main Engine (SSME) hot-fire test at Stennis Space Center and the Low Cost Boost Technology (LCBT) Program.

Tarrant, Charlie↗

Thermophysics Characterization of Kerosene Combustion

A one-formula surrogate fuel formulation and its quasi-global combustion kinetics model are developed to support the design of injectors and thrust chambers of kerosene-fueled rocket engines. This surrogate fuel model depicts a fuel blend that properly represents the general physical and chemical properties of kerosene. The accompanying gaseous-phase thermodynamics of the surrogate fuel is anchored with the heat of formation of kerosene and verified by comparing a series of one-dimensional rocket thrust chamber calculations. The quasi-global combustion kinetics model consists of several global steps for parent fuel decomposition, soot formation, and soot oxidation, and a detailed wet-CO mechanism. The final thermophysics formulations are incorporated with a computational fluid dynamics model for prediction of the combustor efficiency of an uni-element, tri-propellant combustor and the radiation of a kerosene-fueled thruster plume. The model predictions agreed reasonably well with those of the tests.

Wang, Ten-See↗

Thermophysics Characterization of Kerosene Combustion

A one-formula surrogate fuel formulation and its quasi-global combustion kinetics model are developed to support the design of injectors and thrust chambers of kerosene-fueled rocket engines. This surrogate fuel model depicts a fuel blend that properly represents the general physical and chemical properties of kerosene. The accompanying gaseous-phase thermodynamics of the surrogate fuel is anchored with the heat of formation of kerosene and verified by comparing a series of one-dimensional rocket thrust chamber calculations. The quasi-global combustion kinetics model consists of several global steps for parent fuel decomposition, soot formation, and soot oxidation and a detailed wet-CO mechanism to complete the combustion process. The final thermophysics formulations are incorporated with a computational fluid dynamics model for prediction of the combustion efficiency of an unielement, tripropellant combustor and the radiation of a kerosene-fueled thruster plume. The model predictions agreed reasonably well with those of the tests.

Wang, Ten-See↗

High-Speed Recording of Test Data on Hard Disks

Disk Recording System (DRS) is a systems-integration computer program for a direct-to-disk (DTD) high-speed data acquisition system (HDAS) that records rocket-engine test data. The HDAS consists partly of equipment originally designed for recording the data on tapes. The tape recorders were replaced with hard-disk drives, necessitating the development of DRS to provide an operating environment that ties two computers, a set of five DTD recorders, and signal-processing circuits from the original tape-recording version of the HDAS into one working system. DRS includes three subsystems: (1) one that generates a graphical user interface (GUI), on one of the computers, that serves as a main control panel; (2) one that generates a GUI, on the other computer, that serves as a remote control panel; and (3) a data-processing subsystem that performs tasks on the DTD recorders according to instructions sent from the main control panel. The software affords capabilities for dynamic configuration to record single or multiple channels from a remote source, remote starting and stopping of the recorders, indexing to prevent overwriting of data, and production of filtered frequency data from an original time-series data file.

Lagarde, Paul M., Jr.↗

A Potential NASA Research Reactor to Support NTR Development

In support of efforts for research into the design and development of a man rated Nuclear Thermal Rocket (NTR) engine, the National Aeronautics and Space Administration (NASA), Marshall Space Flight Center (MSFC), is evaluating the potential for building a Nuclear Regulatory Commission (NRC) licensed research reactor. The proposed reactor would be licensed by NASA and operated jointly by NASA and university partners. The purpose of this reactor would be to perform further research into the technologies and systems needed for a successful NTR project and promote nuclear training and education.

Eades, Michael↗

Nuclear Thermal Propulsion: Past, Present, and a Look Ahead

NTR: High thrust high specific impulse (2 x LOXLH2 chemical) engine uses high power density fission reactor with enriched uranium fuel as thermal power source. Reactor heat is removed using H2 propellant which is then exhausted to produce thrust. Conventional chemical engine LH2 tanks, turbo pumps, regenerative nozzles and radiation-cooled shirt extensions used -- NTR is next evolutionary step in high performance liquid rocket engines.

Nuclear rocket engines↗

Missions to Triton and Pluto using a Hopper Vehicle with In-Situ Refueling

The Triton Hopper is a NASA Innovative Advanced Concepts (NIAC) project to design a mission to not merely land, but repeatedly fly across the surface of Triton, utilizing the volatile surface ices (primarily nitrogen) as propellant for a radioisotope-heated thermal rocket engine to launch across the surface and explore all the moon's varied terrain. An engineering design study of the vehicle and mission was done. With a calculated range of 20 km per hop, equator-to-pole mobility can be achieved over a primary mission duration of 2 years. Using Nuclear Electric Propulsion for the transfer vehicle, the same concept can be applied for a mission to the surface of Pluto.

Landis, Geoffrey A.↗

Improved Hypersonic Inlet Performance Using Validated Strut Compression Designs

Aerojet is currently executing two Strutjet propulsion contracts: one a Rocket Based Combined Cycle (RBCC) engine for a NASA-Marshall Space Flight Center (MSFC) Advanced Reusable Transportation Technology (ARTT) program, the second a Dual Mode Ram/Scramjet engine for a USAF Wright Laboratories Storable Fuel Scramjet Flow Path Concepts program. The engines employed in both programs operate at supersonic and low hypersonic speeds and use inlets employing forebody external and sidewall compression. Aerojet has developed and validated a successful design methodology applicable to these inlet types. Design features include an integrated vehicle forebody, external side compression struts, strut sidewall and throat bleed, a throat shock trap, and variable geometry internal contraction. Computation Fluid Dynamic (CFD) predictions and test data show these inlets allow substantially increased flow turning angles over other designs. These increased flow turning angles allow shorter and lighter engines than current designs, which in turn enables higher performing vehicles with broad operating characteristics. This paper describes the designs of two different inlets evaluated by the NASA-MSFC and USAF programs, discusses the results of wind tunnel tests performed by NASA-Lewis Research Center, and provides correlations of test data with CFD predictions. Parameters of interest include low Mach number starting capability, start sensitivity as a function of back pressure at various contraction ratios, flow turning angles, strut and throat bleed effects, and pressure recovery at various Mach numbers.

Bulman, M. J.↗