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At least 361 records · Page 20

Space Shuttle Solid Rocket Booster Lightweight Recovery System

The cancellation of the Advanced Solid Rocket Booster Project and the earth-to-orbit payload requirements for the Space Station dictated that the National Aeronautics and Space Administration (NASA) look at performance enhancements from all Space Transportation System (STS) elements (Orbiter Project, Space Shuttle Main Engine Project, External Tank Project, Solid Rocket Motor Project, & Solid Rocket Booster Project). The manifest for launching of Space Station components indicated that an additional 12-13000 pound lift capability was required on 10 missions and 15-20,000 pound additional lift capability is required on two missions. Trade studies conducted by all STS elements indicate that by deleting the parachute Recovery System (and associated hardware) from the Solid Rocket Boosters (SRBS) and going to a lightweight External Tank (ET) the 20,000 pound additional lift capability can be realized for the two missions. The deletion of the parachute Recovery System means the loss of four SRBs and this option is two expensive (loss of reusable hardware) to be used on the other 10 Space Station missions. Accordingly, each STS element looked at potential methods of weight savings, increased performance, etc. As the SRB and ET projects are non-propulsive (i.e. does not have launch thrust elements) their only contribution to overall payload enhancement can be achieved by the saving of weight while maintaining adequate safety factors and margins. The enhancement factor for the SRB project is 1:10. That is for each 10 pounds saved on the two SRBS; approximately 1 additional pound of payload in the orbiter bay can be placed into orbit. The SRB project decided early that the SRB recovery system was a prime candidate for weight reduction as it was designed in the early 1970s and weight optimization had never been a primary criteria.

Wolf, Dean↗

Highlights of Nanosatellite Development Program at NASA-Goddard Space Flight Center

Currently the GN&C's Propulsion Branch of the NASA's Goddard Space Flight Center (GSFC) is conducting a broad technology development program for propulsion devices that are ideally suited for nanosatellite missions. The goal of our program is to develop nanosatellite propulsion systems that can be flight qualified in a few years and flown in support of nanosatellite missions. The miniature cold gas thruster technology, the first product from the GSFC's propulsion component technology development program, will be flown on the upcoming ST-5 mission in 2003. The ST-5 mission is designed to validate various nanosatellite technologies in all major subsystem areas. It is a precursor mission to more ambitious nanosatellite missions such as the Magnetospheric Constellation mission. By teaming with the industry and government partners, the GSFC propulsion component technology development program is aimed at pursuing a multitude of nanosatellite propulsion options simultaneously, ranging from miniaturized thrusters based on traditional chemical engines to MEMS based thruster systems. After a conceptual study phase to determine the feasibility and the applicability to nanosatellite missions, flight like prototypes of selected technology are fabricated for testing. The development program will further narrow down the effort to those technologies that are considered "mission-enabling" for future nanosatellite missions. These technologies will be flight qualified to be flown on upcoming nanosatellite missions. This paper will report on the status of our development program and provide details on the following technologies: Low power miniature cold gas thruster Nanosatellite solid rocket motor. Solid propellant gas generator system for cold gas thruster. Low temperature hydrazine blends for miniature hydrazine thruster. MEMS mono propellant thruster using hydrogen peroxide.

Rhee, Michael S.↗

EELV Booster Assist Options for CEV

Medium lift EELVs may still play a role in manned space flight. To be considered for manned flight, medium lift EELVs must address the short comings in their current boost assist motors. Two options exist: redesign and requalify the solid rocket motors. Replace solid rocket motors (SRMs) with hybrid rocket motors. Hybrid rocket motors are an attractive alternative. They are safer than SRMs. The TRL's Lockheed Martin Small Launch Vehicle booster development substantially lowers the development risk, cost risk, and the schedule risk for developing hybrid boost assist for EELVs. Hybrid boosters testability offsets SRMs higher inherent reliability.Hybrid booster development and recurring costs are lower than SRMs. Performance gains are readily achieved.

McNeal, Curtis, Jr.↗

Marshall Space Flight Center Materials and Processes Laboratory

Marshall?s Materials and Processes Laboratory has been a core capability for NASA for over fifty years. MSFC has a proven heritage and recognized expertise in materials and manufacturing that are essential to enable and sustain space exploration. Marshall provides a "systems-wise" capability for applied research, flight hardware development, and sustaining engineering. Our history of leadership and achievements in materials, manufacturing, and flight experiments includes Apollo, Skylab, Mir, Spacelab, Shuttle (Space Shuttle Main Engine, External Tank, Reusable Solid Rocket Motor, and Solid Rocket Booster), Hubble, Chandra, and the International Space Station. MSFC?s National Center for Advanced Manufacturing, NCAM, facilitates major M&P advanced manufacturing partnership activities with academia, industry and other local, state and federal government agencies. The Materials and Processes Laborato ry has principal competencies in metals, composites, ceramics, additive manufacturing, materials and process modeling and simulation, space environmental effects, non-destructive evaluation, and fracture and failure analysis provide products ranging from materials research in space to fully integrated solutions for large complex systems challenges. Marshall?s materials research, development and manufacturing capabilities assure that NASA and National missions have access to cutting-edge, cost-effective engineering design and production options that are frugal in using design margins and are verified as safe and reliable. These are all critical factors in both future mission success and affordability.

Tramel, Terri L.↗

Designing the Space Shuttle Propulsion System

The major elements of the Space Shuttle Main Propulsion System include two reusable solid rocket motors integrated into recoverable solid rocket boosters, an expendable external fuel and oxidizer tank, and three reusable Space Shuttle Main Engines. Both the solid rocket motors and space shuttle main engines ignite prior to liftoff, with the solid rocket boosters separating about two minutes into flight. The external tank separates after main engine shutdown and is safely expended in the ocean. The SSME's, integrated into the Space Shuttle Orbiter aft structure, are reused after post landing inspections. Both the solid rocket motors and the space shuttle main engine throttle during early ascent flight to limit aerodynamic loads on the structure. The configuration is called a stage and a half as all the propulsion elements are active during the boost phase, and the SSME's continue operation to achieve orbital velocity approximately eight and a half minutes after liftoff. Design and performance challenges were numerous, beginning with development work in the 1970 s. The solid rocket motors were large, and this technology had never been used for human space flight. The SSME s were both reusable and very high performance staged combustion cycle engines, also unique to the Space Shuttle. The multi body side mount configuration was unique and posed numerous integration and interface challenges across the elements. Operation of the system was complex and time consuming. This paper discusses a number of the system level technical challenges including development and operations.

Owen, James↗

Characterization of the non axial thrust generated by large solid propellant rocket motors in three axis stabilized ascent

Nonaxial thrusts produced by solid rocket motors during three-axis stabilized attitude control have been determined from ascent experience on twenty three Burner II, Burner IIA and Block 5D-1 upper stage vehicles. A data base representing four different rocket motor designs (three spherical and one extended spherical) totaling twenty five three-axis stabilized firings is generated. Solid rocket motor time-varying resultant and lateral side force vector magnitudes, directions and total impulses, and roll torque couple magnitudes, directions, and total impulses are tabulated in the appendix. Population means and three sigma deviations are plotted. Existing applicable ground test side force and roll torque magnitudes and total impulses are evaluated and compared to the above experience data base. Within the spherical motor population, the selected AEDC ground test data consistently underestimated experienced motor side forces, roll torques and total impulses. Within the extended spherical motor population, the selected AEDC test data predicted experienced motor side forces, roll torques, and total impulses, with surprising accuracy considering the very small size of the test and experience populations.

Kosmann, W. J.↗

Micromechanical simulation of damage progression in carbon phenolic composites

Carbon/phenolic composites are used extensively as ablative insulating materials in the nozzle region of solid rocket motors. The current solid rocket motor (RSRM) on the space shuttle is fabricated from woven rayon cloth which is carbonized and then impregnated with the phenolic resin. These plies are layed up in the desired configuration and cured to form the finished part. During firing, the surface of the carbon/phenolic insulation is exposed to 5000 F gases from the rocket exhaust. The resin pyrolizes and the material chars to a depth which progresses with time. The rate of charring and erosion are generally predictable, and the insulation depth is designed to allow adequate safety margins over the firing time of the motor. However, anomalies in the properties and response of the carbon/phenolic materials can lead to severe material damage which may decrease safety margins to unacceptable levels. Three macro damage modes which were observed in fired nozzles are: ply lift, 'wedge out', and pocketing erosion. Ply lift occurs in materials with plies oriented nearly parallel to the surface. The damage occurs in a region below the charred material where material temperatures are relatively low - about 500 F. Wedge out occurs at the intersection of nozzle components whose plies are oriented at about 45 deg. The corner of the block of material breaks off along a ply interface. Pocketing erosion occurs in material with plies oriented normal to the surface. Thermal expansion is restrained in two directions resulting in large tensile strains and material failure normal to the surface. When a large section of material is removed as a result of damage, the insulation thickness is reduced which may lead to failure of the nozzle due to excessive heating of critical components. If these damage events cannot be prevented with certainty, the designer must increase the thickness of the insulator thus adding to both weight and cost. One of the difficulties in developing a full understanding of these macro damage mechanisms is that the loading environment and the material response to that environment are extremely complex. These types of damage are usually only observed in actual motor firings. Therefore, it is difficult and expensive to evaluate the reliability of new materials. Standard material tests which measure mechanical and thermal properties of test specimens can only provide a partial picture of how the material will respond in the service environment. The development of the ANALOG test procedure which can combine high heating rates and mechanical loads on a specimen will improve the understanding of the interactive effects of the various loads on the system. But a mechanistic model of material response which can account for the heterogeneity of the material, the progression of various micromechanical damage mechanisms, and the interaction of mechanical and thermal stresses on the material is required to accurately correlate material tests with response to service environments. A model based on fundamental damage mechanisms which is calibrated and verified under a variety of loading conditions will provide a general tool for predicting the response of rocket nozzles. The development of a micromechanical simulation technique was initiated and demonstrated to be effective for studying across-ply tensile failure of carbon/phenolic composites.

Slattery, Kerry T.↗

Shuttle Propulsion Overview - The Design Challenges

The major elements of the Space Shuttle Main Propulsion System include two reusable solid rocket motors integrated into recoverable solid rocket boosters, an expendable external fuel and oxidizer tank, and three reusable Space Shuttle Main Engines. Both the solid rocket motors and space shuttle main engines ignite prior to liftoff, with the solid rocket boosters separating about two minutes into flight. The external tank separates, about eight and a half minutes into the flight, after main engine shutdown and is safely expended in the ocean. The SSME's, integrated into the Space Shuttle Orbiter aft structure, are reused after post landing inspections. The configuration is called a stage and a half as all the propulsion elements are active during the boost phase, with only the SSME s continuing operation to achieve orbital velocity. Design and performance challenges were numerous, beginning with development work in the 1970's. The solid rocket motors were large, and this technology had never been used for human space flight. The SSME s were both reusable and very high performance staged combustion cycle engines, also unique to the Space Shuttle. The multi body side mount configuration was unique and posed numerous integration and interface challenges across the elements. Operation of the system was complex and time consuming. This paper describes the design challenges and key areas where the design evolved during the program.

Owen, James W.↗

Space shuttle propulsion systems

This is a presentation of view graphs. The design parameters are given for the redesigned solid rocket motor (RSRM), the Advanced Solid Rocket Motor (ASRM), Space Shuttle Main Engine (SSME), Solid Rocket Booster (SRB) separation motor, Orbit Maneuvering System (OMS), and the Reaction Control System (RCS) primary and Vernier thrusters. Space shuttle propulsion issues are outlined along with ASA program definition, ASA program selection methodology, its priorities, candidates, and categories.

Bardos, Russell↗

Methyl Chloroform Elimination from the Production of Space Shuttle Sold Rocket Motors

Thiokol Space Operations manufactures the Reusable Solid Rocket Motors used to launch America's fleet of Space Shuttles. In 1989, Thiokol used more than 1.4 Mlb of methyl chloroform to produce rocket motors. The ban placed by the Environmental Protection Agency on the sale of methyl chloroform had a significant effect on future Reusable Solid Rocket Motor production. As a result, changes in the materials and processes became necessary. A multiphased plan was established by Thiokol in partnership with NASA's Marshall Space Flight Center to eliminate the use of methyl chloroform in the Reusable Solid Rocket Motor production process. Because of the extensive scope of this effort, the plan was phased to target the elimination of the majority of methyl chloroform use (90 percent) by January 1, 1996, the 3 Environmental Protection Agency deadline. Referred to as Phase I, this effort includes the elimination of two large vapor degreasers, grease diluent processes, and propellant tooling handcleaning using methyl chloroform. Meanwhile, a request was made for an essential use exemption to allow the continued use of the remaining 10 percent of methyl chloroform after the 1996 deadline, while total elimination was pursued for this final, critical phase (Phase II). This paper provides an update to three previous presentations prepared for the 1993, 1994, and 1995 CFC/Halon Alternative Conferences, and will outline the overall Ozone Depleting Compounds Elimination Program from the initial phases through the final testing and implementation phases, including facility and equipment development. Processes and materials to be discussed include low-pressure aqueous wash systems, high-pressure water blast systems- environmental shipping containers, aqueous and semi-aqueous cleaning solutions, and bond integrity and inspection criteria. Progress toward completion of facility implementation and lessons learned during the scope of the program, as well as the current development efforts and basic requirements of future methyl chloroform handcleaning elimination, will also be outlined.

Golde, Rick P.↗

New Solid Propellant Additives: Evaluation for NASA Mission Use Cases

Researchers and small companies have been investigating and developing new solid rocket motor propellant ingredients with renewed vigor. Lithium-aluminum alloy is an ingredient of particular interest, but most of the advertisement about its benefits are focused on defense tactical rocket applications. This paper develops a framework to evaluate this and other propellants against standard aluminized composite propellant for mass-limited missions like many NASA in-space applications. It shows a way to estimate density’s effect with an exponent less than 1 depending on mission and technology parameters, and an algorithm for directly calculating delta-velocity or payload performance improvement.

Lithium-aluminum↗

Solid propellant rocket motor

The characteristics of a solid propellant rocket engine with a controlled rate of thrust buildup to a desired thrust level are discussed. The engine uses a regressive burning controlled flow solid propellant igniter and a progressive burning main solid propellant charge. The igniter is capable of operating in a vacuum and sustains the burning of the propellant below its normal combustion limit until the burning propellant surface and combustion chamber pressure have increased sufficiently to provide a stable chamber pressure.

Dowler, W. L.↗