Multi-layered Propellant Grain with Uniform Binder System
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Solution Overview
Problem
Traditional multi-layered propellant compositions experience ingredient migration between layers during storage and aging, leading to loss of ballistic benefits due to differing gas generation rates, particularly exacerbated at elevated temperatures.
Innovation Solution
A multi-layered propellant grain composition with an outer slow-burning layer comprising nitroguanidine or 1,1-diamino2,2-dinitroethene and an inner fast-burning layer comprising HMX, both using cellulosic binders and the same plasticizers, with binder-to-plasticizer ratios maintained across layers to prevent component migration and retain burn rate differential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multi-layered propellant compositions are used with different gas generation rates, then ballistic efficiency is improved through progressive gas generation, but ingredient migration occurs between layers during storage and aging
Solution Approach 1:
The patent applies local quality by making the binder and plasticizer components identical in both layers while maintaining different energetic materials. This creates a localized composition strategy where the binding system is standardized to prevent migration, while the energetic content varies to provide different burn rates. The outer layer uses nitroguanidine or 1,1-diamino-2,2-dinitroethene with the inner layer using HMX, both bound by the same cellulosic binder and plasticizer system.
Solution Approach 2:
The patent employs parameter changes by carefully controlling the binder-to-plasticizer ratio to be substantially equal in both layers, and by selecting specific energetic materials with different gas generation rates. This parameter optimization prevents migration by ensuring comparable binding characteristics while maintaining the desired burn rate differential for progressive gas generation.
2Power
If the burn rate differential between layers is large enough to achieve ideal progressivity, then gun pressure optimization is improved, but ingredient migration is exacerbated at elevated temperatures
Solution Approach 1:
The patent applies homogeneity by using the same binder and plasticizer system in both layers, creating uniform binding characteristics that resist temperature-induced migration. This homogeneous binding system maintains structural integrity and prevents component movement even when temperature variations occur, while still allowing the energetic materials to provide different burn rates for pressure optimization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents ingredient migration, maintaining desirable burn rate characteristics and progressivity, thereby enhancing ballistic efficiency by ensuring consistent performance over time and temperature.
Implementation Method 1
the gases generated by the ignition of the propellant impart a large force which accelerates the projectile down the barrel
Implementation Method 2
the expansion effect from the burning propellant will increase until a maximum pressure is reached
Data Source
AI summary
The present invention is directed to propellant grains having multiple layers consisting of an outer, slow burning, layer composition and an inner, fast burning, layer with desirable progressivity burn rates. The outer, slow burning, layer comprising a first energetic material, a first plasticizer and a first binder and an inner, fast burning, layer comprising a second energetic material, and the same plasticizer as the outer layer, and a second binder. The compositions in the propellant grain provided herein provides for a burn rate energy differential between the outer, slow burning, layer and inner, fast burning, layer of at least 2.