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Long-Duration Proportional Thruster for Navy Hot-Gas Control System

Description:

TECHNOLOGY AREA(S): Materials, Weapons 

OBJECTIVE: Develop and evaluate advanced, innovative concepts for proportional thrusters for application to the Navy Trident II (D5) strategic missile post-boost control system (PBCS). The proportional thruster design and material selection must advance the state-of-the-art to meet Navy goals for burn-time duration (up to 1,000 seconds) while being compatible with flame temperatures and the chemical environment of D5 PBCS operation. Strategic Systems Programs (SSP) will make available the baseline PBCS System Design Requirements Document and applicable baseline Weapon Specifications upon request. Requests will be in accordance with process defined in SSPINST 5540.2D. 

DESCRIPTION: In the 21st century, advances have been made in the area of proportional thrusters for solid propellant, hot-gas controls systems by Navy, Air Force, Missile Defense Agency (MDA), and National Space and Aeronautics Administration (NASA) development programs. Hot-gas controls systems must be constructed using materials that are thermally, structurally, and chemically compatible with the propellant gases. Higher propellant gas temperatures are a common feature of higher energy control systems. In general, these conditions prevent the use of traditional refractory metals because their strengths diminish significantly with increasing temperature. Phase stability diagrams shed light on microstructural effects, and are calculated from thermodynamic predictions of what phases will exist at a specific temperature and levels of oxygen and carbon in the gas. Using gas thermochemistry calculations, phase stability diagrams predict what phases will be stable given the gas composition. The ratio of carbon monoxide to carbon dioxide is applied to determine the partial pressure of oxygen in the system. At a given temperature, a gas mixture with a lower ratio of carbon monoxide to carbon dioxide (CO:CO2) has a more severe oxidizing environment; this enables one to create oxidizing environments in the laboratory that approximate the oxidizing environments of a range of gas generator propellants, including Navy 1.1 propellant. This is used to conduct 3,000° Fahrenheit testing of thruster material compatibility in an oxidizing environment representative of propellant combustion products. Material science principles must be applied in the development of a hot-gas component. Understanding the environment, time at temperature and pressure, adjacent materials, gas chemistry interactions, thermodynamics, and kinetics is paramount to selecting a material that will survive and provide mission success. The Navy SSP development of additional PBCS valves is expected to begin in the early-to-mid-2020’s; this SBIR topic will reduce the technical risk of proportional thrusters before the Navy SSP development program begins and positions the program to make an informed decision on whether to re-create the D5 PBCS valves or replace them with proportional thrusters. The proportional thruster design and material selection must advance the state of the art to meet Navy goals for burn-time duration (up to 1,000 seconds) while being compatible with flame temperatures (3,000° Fahrenheit) and the chemical environment of Navy Class 1.1 gas generator combustion products. The combination of extended burn time and compatibility with high flame temperature and oxidizing combustion products presents an extreme technical challenge for which development of innovative technologies is required. The proportional thruster design and material selection must advance the state-of-the-art to meet Navy goals for burn-time duration (up to 1,000 seconds) while being compatible with flame temperatures (3,000° degrees Fahrenheit) and the chemical environment of Navy Class 1.1 gas generator combustion products. The combination of extended burn time and compatibility with high flame temperature and oxidizing combustion products presents an extreme technical challenge for which development of innovative technologies is required. Strategic Systems Programs will make available the technical data regarding the PBCS gas generator's combustion products upon request. Request will be in accordance with process defined in SSPINST 5540.2D. 

PHASE I: Develop technical concepts for proportional thrusters for solid-propellant, hot-gas control systems. Conduct top-level trade studies, design concepts, model performance, and perform key tests to transition from Phase I to a Phase II. Work with Navy SSP to establish key technical requirements for burn-time duration, thrust versus time, flame temperature compatibility, and compatibility with the combustion products of Navy PBCS gas generator propellants. Use model-based engineering (MBE) techniques to develop technical concepts of designs for proportional thrusters. Develop and apply technologies to meet the thermal-management challenge of a long-duration burn time (1,000 seconds) with flame temperatures approximately 3,000° Fahrenheit. Conduct top-level thermal and structural analyses of the MBE-generated design. Develop a proportional-thruster performance model for attaining the thrust versus time profile required for Navy PBCS application. Identity risks to the technical approach and develop plans to mitigate those risks for Phase II. Elucidate the technical approach to the thermal management challenge and risk of a long-duration burn time (1,000 seconds) with flame temperatures of 3,000° Fahrenheit. 

PHASE II: Design and fabricate a breadboard, flight-design proportional thruster that will include attach points for integration with the gas generator. Conduct a Systems Requirements Review (SRR) and Preliminary Design Review (PDR) with Navy SSP. Conduct laboratory experiments and/or modeling as needed to verify the proposed breadboard concept for proportional thrusters. Conduct material compatibility and hot-gas testing of key components for the breadboard concept for the proportional thruster. Note: The small business may subcontract this work to a laboratory capable of conducting hot-gas tests at 3,000° Fahrenheit in an oxidizing environment that emulates that of D5 gas generator combustion products. Conduct a static-fire test of the flight-design, breadboard proportional thruster at the small business facility. The test will be designed to run the full-duration of 1,000 seconds using a standard, work-horse gas generator and a thrust-time duty cycle that is representative of the D5 PBCS. Conduct a post-test evaluation of the breadboard proportional thruster, write a Test Report, and conduct a post-test review with Navy SSP. 

PHASE III: Develop a prototype flight design concept for a proportional thruster using model-based engineering techniques. The prototype flight design will meet technical goals for burn-time duration and compatibility with D5 flame temperatures and combustion products. Refine the breadboard design based on results and lessons learned from Phase II static-fire tests. Fabricate a prototype flight design proportional thruster. The prototype design will include attach points for integration with the gas generator. Conduct a Critical Design Review (CDR) with Navy SSP. Provide a prototype proportional thruster for testing with a Navy SSP-provided gas generator and associated test components at a Government facility (e.g., the Naval Air Weapons Center (NAWC) at China Lake, CA). Perform post-test analysis of the fired proportional thruster to assess erosion of thruster materials and compatibility with the flame temperature and combustion products of the test. Post-test analysis should include: Pre- and post-test component weights, macro photos, and dimensional analysis. Following these non-destructive measurements, metallographic sections will be prepared and analyzed at low and high magnification. Scanning Electron Microscopy (SEM) will also be used to understand oxidation and microstructural changes of thruster materials the occurred during the static-fire test. There is the potential that proportional valve technology developed on this SBIR project could be adapted for use on proportional thrusters for NASA and/or commercial spacecraft. 

REFERENCES: 

1: Sutton, George P., and Oscar Biblarz. "Rocket Propulsion Elements." Hoboken: John Wiley & Sons Inc., 2010. 8th Edition, p. 236-9. ISBN 978-0-470-08024-5. https://www.amazon.com/Rocket-Propulsion-Elements-George-Sutton/dp/0470080248

2:  Lee, J. et al. "Study on the Performance Characteristics of Blunt Body Pintle Nozzle." 49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, June 2013. https://arc.aiaa.org/doi/abs/10.2514/6.2013-4080

3:  Ponzo, J. et al. "Long Duration Hot Gas Valve Demonstration." 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

4:  August 2009. http://enu.kz/repository/2009/AIAA-2009-5483.pdf

5:  "Systems and Software Engineering – Systems Life Cycle Processes." IEEE 15288 (2015). https://www.iso.org/standard/63711.html

6:  "IEEE Standard for Application of Systems Engineering on Defense Programs." IEEE 15288.1 (2014). https://standards.ieee.org/findstds/standard/15288.1-2014.html

7:  "Standard for Technical Reviews and Audits on Defense Programs." IEEE 15288.2 (2014). https://standards.ieee.org/findstds/standard/15288.2-2014.html

8:  "Department of Standard Practices: Technical Data Packages." MIL-STD-31000 Rev. A." http://23.96.237.142/wp-content/uploads/2015/10/MIL-STD-31000A-released-on-ASSIST-3-13-2013.pdf

9:  "Department of Defense Standard Practice: Documentation of Verification, Validation, and Accreditation (VV&A) for Models and Simulations." MIL-STD-3022 Chg. 1. https://www.scribd.com/document/136735764/MIL-STD-3022-Documentation-of-Verification-and-Validation

10:  "Policy and Procedures for Security Review Requests for the Public Release of Unclassified Information Generated Under the Director Strategic Systems Programs, SSPINST 5540.2 Revision D. http://149.32.95.180/ESSPINST/

KEYWORDS: Proportional Thruster; Pintle Valve; Refractory Metals; Hot-Gas Control System; Navy Strategic Missiles 

CONTACT(S): 

Jeffrey Waite 

(202) 433-5816 

jeffrey.waite@ssp.navy.mil 

David Olson 

(202) 433-5807 

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