Solid rocket motor igniters. NASA space vehicle design criteria, chemical propulsion
Design approach for solid propellant rocket igniters
Source record↗
SEARCH · Search NASA
Results for “chemical design”
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.
Multi-Objective Hybrid Optimal Control for Multiple-Flyby Interplanetary Mission Design using Chemical Propulsion
Preliminary design of high‐thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys and the bodies at which those flybys are performed. For some missions, such as surveys of small bodies, the mission designer also contributes to target selection. In addition, real‐valued decision variables, such as launch epoch, flight times, maneuver and flyby epochs, and flyby altitudes must be chosen. There are often many thousands of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the impulsive mission design problem as a multi‐objective hybrid optimal control problem. The method is demonstrated on several real‐world problems. Two assumptions are frequently made to simplify the modeling of an interplanetary high‐thrust trajectory during the preliminary design phase. The first assumption is that because the available thrust is high, any maneuvers performed by the spacecraft can be modeled as discrete changes in velocity. This assumption removes the need to integrate the equations of motion governing the motion of a spacecraft under thrust and allows the change in velocity to be modeled as an impulse and the expenditure of propellant to be modeled using the time‐independent solution to Tsiolkovsky's rocket equation [1]. The second assumption is that the spacecraft moves primarily under the influence of the central body, i.e. the sun, and all other perturbing forces may be neglected in preliminary design. The path of the spacecraft may then be modeled as a series of conic sections. When a spacecraft performs a close approach to a planet, the central body switches from the sun to that planet and the trajectory is modeled as a hyperbola with respect to the planet. This is known as the method of patched conics. The impulsive and patched‐conic assumptions significantly simplify the preliminary design problem.
Optimization↗
Multi-Objective Hybrid Optimal Control for Multiple-Flyby Interplanetary Mission Design Using Chemical Propulsion
Preliminary design of high-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys and the bodies at which those flybys are performed. For some missions, such as surveys of small bodies, the mission designer also contributes to target selection. In addition, real-valued decision variables, such as launch epoch, flight times, maneuver and flyby epochs, and flyby altitudes must be chosen. There are often many thousands of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the impulsive mission design problem as a multiobjective hybrid optimal control problem. The method is demonstrated on several real-world problems.
Trajectory↗
Chemical engineering design of CO oxidation catalysts
How a chemical reaction engineer would approach the challenge of designing a CO oxidation catalyst for pulsed CO2 lasers is described. CO oxidation catalysts have a long history of application, of course, so it is instructive to first consider the special requirements of the laser application and then to compare them to the characteristics of existing processes which utilize CO oxidation catalysts. All CO2 laser applications require a CO oxidation catalyst with the following characteristics: (1) active at stoichiometric ratios of O2 and CO, (2) no inhibition by CO2 or other components of the laser environment, (3) releases no particulates during vibration or thermal cycling, and (4) long lifetime with a stable activity. In all applications, low consumption of power is desirable, a characteristic especially critical in aerospace applications and, thus, catalyst activity at low temperatures is highly desirable. High power lasers with high pulse repetition rates inherently require circulation of the gas mixture and this forced circulation is available for moving gas past the catalyst. Low repetition rate lasers, however, do not inherently require gas circulation, so a catalyst that did not require such circulation would be favorable from the standpoint of minimum power consumption. Lasers designed for atmospheric penetration of their infrared radiation utilize CO2 formed from rare isotopes of oxygen and this application has the additional constraint that normal abundance oxygen isotopes in the catalyst must not exchange with rare isotopes in the gas mixture.
Herz, Richard K.↗
Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers
The design and chemical synthesis of new media for solar pumped iodine molecule lasers are explored. In an effort to prepare an iodo fluorocarbon compound absorbing strongly at 300 nm or above, the synthesis of perfluoro allylic iodides was investigated. These compounds furnish especially stable allylic radicals upon photodissociation. The desired red shift is anticipated in the absorption maximum could correlate with increasing radical stability. This expectation was based upon the analysis, previously reported, of the structures and absorption maxima of compounds studied earlier. A previously unknown substance was prepared, a prototypical target molecule, perfluoro-3-iodocyclopent-1-ene. It was obtained by reaction of perfluorocyclopentene with sulfur trioxide under the influence of antimony pentafluoride catalyst, followed by treatment of the resulting allylic fluorosulfonate with sodium iodide in sulfoland solvent. Preliminary data indicate that the absorption maximum for the iodo fluorocarbon is not shifted significantly to longer wavelength. It is not certain whether this result reflects an unexpected influence of the cyclic structure upon the position of the absorption maximum.
Shiner, C. S.↗
Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers
This work is directed toward the design and chemical synthesis of new media for solar-pumped I* lasers. In view of the desirability of preparing a perfluoroalkyl iodide absorbing strongly at 300 nm, the relationship betwen perfluoroalkyl iodide structure and the corresponding absorption wavelength was reexamined. Analysis of existing data suggests that, in this family of compounds, the absorption maximum shifts to longer wavelength, as desired, as the C-I bond in the lasant is progressively weakened. Weakening of the C-I bond correlates, in turn, with increasing stability of the perfluoroalkyl radical formed upon photodissociation of the iodide. The extremely promising absorption characteristics of perfluoro-tert-butyl iodide can be accounted for on this basis. A new technique of diode laser probing to obtain precise yields of I* atoms in photodissociation was also developed.
Shiner, C. S.↗
Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers
Research is directed toward the design and synthesis of new media for solar-pumped I* lasers. Since the most effective existing lasants are perfluoroalkyl iodides, a strategy was proposed for the development of improved materials of this type with absorption maxima at 300 nm. Absorption spectra were synthesized and measured for prototypical species containing iodine bound to boron, iron, and cobalt.
Shiner, Christopher S.↗
Multi-Objective Hybrid Optimal Control for Multiple-Flyby Interplanetary Mission Design Using Chemical Propulsion
The customer (scientist or project manager) most often does not want just one point solution to the mission design problem Instead, an exploration of a multi-objective trade space is required. For a typical main-belt asteroid mission the customer might wish to see the trade-space of: Launch date vs. Flight time vs. Deliverable mass, while varying the destination asteroid, planetary flybys, launch year, etcetera. To address this question we use a multi-objective discrete outer-loop which defines many single objective real-valued inner-loop problems.
Design↗
Manned Mars Explorer project: Guidelines for a manned mission to the vicinity of Mars using Phobos as a staging outpost; schematic vehicle designs considering chemical and nuclear electric propulsion
The Manned Mars Explorer (MME) project responds to the fundamental problems of sending human beings to Mars in a mission scenario and schematic vehicle designs. The mission scenario targets an opposition class Venus inbound swingby for its trajectory with concentration on Phobos and/or Deimos as a staging base for initial and future Mars vicinity operations. Optional vehicles are presented as a comparison using nuclear electric power/propulsion technology. A Manned Planetary Vehicle and Crew Command Vehicle are used to accomplish the targeted mission. The Manned Planetary Vehicle utilizes the mature technology of chemical propulsion combined with an advanced aerobrake, tether and pressurized environment system. The Crew Command Vehicle is the workhorse of the mission performing many different functions including a manned Mars landing, and Phobos rendezvous.
Nolan, Sean↗
Metal-Templated Design of Chemically Switchable Protein Assemblies with High-Affinity Coordination Sites
To mimic a hypothetical pathway for protein evolution, we previously tailored a monomeric protein (cyt cb562) for metal-mediated self-assembly, followed by re-design of the resulting oligomers for enhanced stability and metal-based functions. We show that a single hydrophobic mutation on the cyt cb562 surface drastically alters the outcome of metal-directed oligomerization to yield a new trimeric architecture, (TriCyt1)3. This nascent trimer was redesigned into second and third-generation variants (TriCyt2)3 and (TriCyt3)3 with increased structural stability and preorganization for metal coordination. The three TriCyt variants combined furnish a unique platform to 1) provide tunable coupling between protein quaternary structure and metal coordination, 2) enable the construction of metal/pH-switchable protein oligomerization motifs, and 3) generate a robust metal coordination site that can coordinate all mid-to-late first-row transition-metal ions with high affinity.
Albert Kakkis↗
Glossary of terms and table of conversion factors used in design of chemical propulsion systems
The glossary presented is based entirely on terms used in the monographs on Chemical Propulsion. Significant terms relating to material properties and to material fabrication are presented. The terms are arranged in alphabetical order, with multiple word terms appearing in the normal sequence of usage; for example, ablative cooling appears as such, not as cooling, ablative, and lip seal appears as such, not as seal, lip. Conversion Factors for converting U.S. customary units to the International System of Units are presented in alphabetical order of the physical quantity (e.g., density, heat flux, specific impulse) involved.
Keller, R. B., Jr.↗
Human Mars Mission: Weights and Mass Properties
This paper presents a final report on The Human Mars Mission Weights and Measures. The topics included in this report are: 1) Trans-Earth Injection Storage Human Mars Mission (HMM) Chemical Design Reference Mission (DRM) v4.0a Weight Breakout; 2) Ascent Stage HMM Chemical DRM v4.0a Weight Breakout; 3) Descent Stages HMM Chemical DRM v4.0a Weight Breakout; 4) Trans-Mars Injection Stages HMM Chemical DRM v4.0a Weight Breakout; 5) Trans-Earth Injection Stage HMM Solar Electric Propulsion (SEP) DRM v4.0a Weight Breakout; 6) Ascent Stage HMM SEP DRM v4.0a Weight Breakout; 7) Descent Stages HMM SEP DRM v4.0a Weight Breakout; 8) Trans-Mars Injection Stages HMM SEP DRM v4.0a Weight Breakout; 9) Crew Taxi Stage HMM SEP DRM v4.0 Weight Breakout; 10)Trans-Earth Injection Stage HMM Nuclear DRM v4.0a Weight Breakout; 11) Ascent Stage HMM Nuclear DRM v4.0a Weight Breakout; 12) Descent Stages HMM Nuclear DRM v4.0a Weight Breakout; 13) Trans-Mars Injection Stages HMM Nuclear DRM v4.0a Weight Breakout; and 14) HMM Mass Properties Coordinate System.
Brothers, Bobby↗
Cesium-diode performances from the 1963-to-1971 Thermionic Conversion Specialist Conferences
Indexes and summaries of the conference papers containing cesium-diode results are presented. Lists of converter materials, geometries, conditions, outputs, and lifetimes accompany the references. Simple chemical designations for emitters, collectors, and additives direct the reader to appropriate selections.
Morris, J. F.↗
Propellant material compatibility program and results
The effects of long-term (up to 10 years) contact of inert materials with earth-storable propellants were studied for the purpose of designing chemical propulsion system components that can be used for current as well as future planetary spacecraft. The primary experimental work, and results to date are reported. Investigations include the following propellants: hydrazine, hydrazine-hydrazine nitrate blends, monomethyl-hydrazine, and nitrogen tetroxide. Materials include: aluminum alloys, corrosion-resistant steels, and titanium alloys. More than 700 test specimen capsules were placed in long-term storage testing at 43 C in the special material compatibility facility. Material ratings relative to the 10-year requirement have been assigned.
Toth, L. R.↗
Long term compatibility of nitrogen tetroxide with metals - Results at the ten-year milestone
Analyses and results are reported of a test program to establish the effects of long-term (10 years or more) contact of materials with nitrogen textroxide MON-1 for the purpose of designing chemical propulsion system components which can be used for current as well as future planetary spacecraft. The test materials included aluminum alloy, corrosion-resistant steel, titanium alloy, and nickel. The weight and appearance of each specimen were observed, including the presence of deposits, etching, pitting, and cracking. Aluminum alloy and steel were rated satisfactory with minor reservations, titanium alloy was satisfactory, and nickel was unsatisfactory. Criteria for ratings are shown.
Moran, C. M.↗
Propellant/material compatibility program and results: Ten-year milestones
The analyses and results of a test program to establish the effects of long term (10 years or more) contact of materials with earth-storable propellants for the purpose of designing chemical propulsion system components which are used for current as well as future planetary spacecraft are described. The period from the publication of JPL TM 33-779 IN 1976 through the testing accomplished in 1981 is covered. The following propellants are reported herein: hydrazine, monomethylhydrazine and nitrogen tetroxide. Materials included the following: aluminum alloys, corrosion resistant steels and a titanium alloy. The results of the testing of more than 80 specimens are included. Material ratings relative to the ten year milepost were assigned. Some evidence of propellant decomposition was found. Titanium is rated as acceptable for ten year applications. Aluminum and stainless steel alloys are also rated as acceptable with few restrictions.
Moran, C.↗
Long term compatability of hydrazine with metals: Results at the ten-year milestone
A test program to establish the effects of long term contact of materials with hydrazine for the purpose of designing chemical propulsion system components which can be used for current as well as future planetary spacecraft was analyzed. Materials included the following: aluminum alloys, corrosion resistant steels, and a titanium alloy. Material ratings relative to the 10 year milepost are assigned. The propellant was found to be stable. With minor exceptions, the materials tested were rated acceptable for a 10 year mission.
Moran, C. M.↗
Long term exposure of metals to hydrazine nitrate blend
A long term testing program is being conducted to determine the effects of materials in contact with a hydrazine nitrate blend for the purpose of designing chemical propulsion systems which can be used for current as well as future planetary spacecraft. Analysis of this data indicates that some aluminum alloys are acceptable for use with the particular blend of fuel used. Titanium alloy was identified as being acceptable for 10-year applications. Corrosion resistant steels, however, were found to have excessive corrosion rates and are therefore considered unacceptable for long-term use. There is also some evidence that the propellant decomposed at a rate far in excess of the acceptable rate of 0.1 percent per year when in contact with stainless steel.
Moran, Clifford M.↗