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Formulation and Testing of Paraffin-Based Solid Fuels Containing Energetic Additives for Hybrid RocketsMany approaches have been considered in an effort to improve the regression rate of solid fuels for hybrid rocket applications. One promising method is to use a fuel with a fast burning rate such as paraffin wax; however, additional performance increases to the fuel regression rate are necessary to make the fuel a viable candidate to replace current launch propulsion systems. The addition of energetic and/or nano-sized particles is one way to increase mass-burning rates of the solid fuels and increase the overall performance of the hybrid rocket motor.1,2 Several paraffin-based fuel grains with various energetic additives (e.g., lithium aluminum hydride (LiAlH4) have been cast in an attempt to improve regression rates. There are two major advantages to introducing LiAlH4 additive into the solid fuel matrix: 1) the increased characteristic velocity, 2) decreased dependency of Isp on oxidizer-to-fuel ratio. The testing and characterization of these solid-fuel grains have shown that continued work is necessary to eliminate unburned/unreacted fuel in downstream sections of the test apparatus.3 Changes to the fuel matrix include higher melting point wax and smaller energetic additive particles. The reduction in particle size through various methods can result in more homogeneous grain structure. The higher melting point wax can serve to reduce the melt-layer thickness, allowing the LiAlH4 particles to react closer to the burning surface, thus increasing the heat feedback rate and fuel regression rate. In addition to the formulation of LiAlH4 and paraffin wax solid-fuel grains, liquid additives of triethylaluminum and diisobutylaluminum hydride will be included in this study. Another promising fuel formulation consideration is to incorporate a small percentage of RDX as an additive to paraffin. A novel casting technique will be used by dissolving RDX in a solvent to crystallize the energetic additive. After dissolving the RDX in a solvent chosen for its compatibility with both paraffin and RDX, the mixture will be combined with the melted paraffin. With the melting point of the paraffin far below the decomposition temperature of the RDX, the solvent will be boiled off, leaving the crystallized RDX embedded in the paraffin. At low percentages of RDX additive and with crystallized RDX surrounded by paraffin, the fuel grains will remain inert, maintaining a key benefit of hybrids in the safety of the solid fuel.
Document ID
20120015329
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Larson, Daniel B.
(Pennsylvania State Univ. University Park, PA, United States)
Boyer, Eric
(Pennsylvania State Univ. University Park, PA, United States)
Wachs,Trevor
(Pennsylvania State Univ. University Park, PA, United States)
Kuo, Kenneth K.
(Pennsylvania State Univ. University Park, PA, United States)
Story, George
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 26, 2013
Publication Date
July 9, 2012
Subject Category
Propellants And Fuels
Report/Patent Number
M11-1186
Meeting Information
Meeting: 9th International Symposium on Special Topics in Chemical Propulsion
Location: Quebec City
Country: Canada
Start Date: July 9, 2012
End Date: July 13, 2012
Distribution Limits
Public
Copyright
Public Use Permitted.
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