| ||The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.|| Objective: ||Polymer Matrix Composites (PMCs) have the potential to increase rocket performance by decreasing the weight of components. This program will develop & demonstrate innovative PMCs for rocket components.
|| Description: ||Materials development for rocket applications poses significant technical challenges due to the harsh environments in which they operate. The interior of a solid rocket motor (SRM) can reach temperatures greater than 3000<sup>o</sup><sup>C</sup>. For this reason an ablative insulator is typically used to shield the rocket motor case, limiting the bulk case temperature below the glass transition temperature of the composite matrix. In addition, the external temperatures of a solid rocket motor can exceed 340<sup>o</sup><sup>C</sup>. Materials that are developed for liquid rocket engine (LRE) applications must survive severe service environments (including operating temperatures of -400<sup>o</sup><sup>C</sup> to 4000<sup>o</sup><sup>C</sup>), show good wear resistance, and have a high heat distortion temperature. Considering these requirements, the use of PMCs in rocket applications presents considerable challenges. However, PMCs have the potential to increase the performance, reliability, and affordability of rocket propulsion. These features are critical to the advancement of space access and DoD missile programs.
Recent joint DoD/NASA/Industry efforts demonstrated the need for innovative technology development efforts for these materials. In particular, developing materials that will reduce the inert weight of the rocket is critical. Consider that a 44% weight reduction for a solid rocket motor represents a 7.4% payload increase and a 10% increase in thrust-to-weight ratio of a LOX/ Kerosene engine results in a payload increase of approximately 200 lbs. By reducing the inert weight of either a liquid or a solid rocket system, significant improvements in payload capabilities are possible. Examples of enabling technologies for polymer matrix composite rocket components include, but are not limited to, high temperature composite resins, advanced ceramic and/or carbon based fibers for SRM cases, and various cost-effective thermoplastic LRE components such as ducting, turbine seals, shrouds and nozzle extensions.
The insulated case of a boost or orbit transfer solid rocket motor comprises about one-half of the inert weight of the rocket. An increase in performance of these systems as well as LREs can be realized by reducing the total weight of the vehicle. For example, increasing the thrust to weight ratio of a liquid engine from 80 to 100 decreases the dry weight of the rocket by 7.6%. This will result in decreased acquisition costs. Additional benefits of PMCs can also be realized as the next generation of systems is developed. Next generation SRMs will operate at higher speeds and may require external thermal protection systems, provided existing state-of-the-art composite matrices are utilized. A high temperature-capable composite resin offers the design engineer an expanded list of options, including the reduction or elimination of the external insulation. Reduction or elimination of the exterior insulation directly influences the overall inert weight of the motor. In volume limited systems, the reduction or elimination of the exterior insulation reduces not only the overall inert weight but also increases the propellant mass fraction of the motor and, therefore, the delivered energy per unit mass at the system level.
There are several methods in which the engine/motor weight can be reduced using these technologies. For example, the weight of the composite SRM case/LRE structural jacket can be reduced by reducing the thickness of the case/jacket or reducing the density of the materials utilized. This can be accomplished by producing materials with higher specific strength and stiffness and/or reduced density. The development of new fibers for composites is an enabling technology to achieve this goal. In addition to the performance benefits, there exists a national need for the domestic development of advanced fibers for aerospace applications. Most high performance aerospace fibers have either been discontinued or the manufacturing of the fibers has shifted overseas. In either circumstance, this is a serious concern for the aerospace community and national security.
High performance thermoplastic PMC development may also be an enabling technology for cost-effective liquid and solid rocket components. The use of high performance thermoplastics has been hindered in the past by the high cost of the materials. With the increased use of these materials, some of which are qualified on the F-22, E3 Sabot, EH-101 helicopter and Airbus A320, the demand for the materials will increase and the cost will decrease substantially. In addition, the processing of these materials does not include costly autoclave curing cycles, thus reducing the processing time and decreasing the cost to manufacture the component. The use of nanoparticles to modify these materials may also improve properties due to increased crystallization of the polymer, as well as decreasing microcracking and making the material more compatible with the fuels and oxidizers utilized in LREs.
The proposed material development efforts are anticipated to provide significant enhancement over existing domestic and foreign state-of-the-art materials. To increase the probability of successful transition to Phase III, the technology development efforts proposed should leverage existing capability and rocket technology development efforts to the maximum extent possible.
|| ||PHASE I: Demonstrate the feasibility and benefit of polymer matrix composites in rocket components. This work will include a description of the system benefit of the PMC technology as well as analysis and/or exploratory research designed to understand the challenges of using the proposed material solution.
|| ||PHASE II: Fabricate and demonstrate polymer matrix composite prototype rocket component. The component will be designed so that it can be cost-effectively tested in relevant rocket environments. In addition, provide a detailed plan for scaling-up and additional testing. Required Phase II deliverables will also include a prototype rocket component.
|| ||PHASE III DUAL USE APPLICATIONS: This effort supports current and future DoD ballistic missile and space launch applications. It will also support commercial space launch vehicle development.
|| References: ||
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9. IHPRPT Website: http://www.pr.afrl.af.mil/technology/IHPRPT/ihprpt.html
10. Cytec Engineering Materials Website: http://www.cytec.com/business/EngineeredMaterials/apc.shtm
|Keywords: ||solid rocket motor, liquid rocket engine, polymer matrix composites, motor performance, thermoplastic, nanomaterials|