Dimer Fatty Diol Solid Propellant Burn Rate Control
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Solution Overview
Problem
Conventional solid propellants face challenges in controlling burn rates, with high burn rates risking rocket motor damage and low burn rates leading to insufficient thrust, and the use of Dimeryl diisocyanate (DDI) is costly and at risk of obsolescence due to its high production costs and potential discontinuation.
Innovation Solution
A precursor formulation comprising hydroxyl-terminated polybutadiene (HTPB) or hydroxyl-terminated polyether (HTPE) prepolymer, an oxidizer, and a dimer fatty diol with an isocyanate curative is used to produce a solid propellant, which reduces burn rates without compromising performance and replaces DDI with a more cost-effective and sustainable dimer fatty diol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DDI is used as burn rate suppressant, then burn rate is controlled, but cost increases significantly
Solution Approach 1:
The patent replaces expensive DDI with a cheaper alternative burn rate suppressant. The formulation uses cost-effective materials that achieve the same burn rate control function without the high production cost and obsolescence risk associated with DDI
Solution Approach 2:
The patent modifies the chemical composition parameters by substituting DDI with alternative suppressants and adjusting the formulation ratios. This involves changing the chemical structure and properties of the binder system while maintaining the desired burn rate characteristics through parameter optimization
2Power
If burn rate is increased, then thrust is improved, but rocket motor damage risk increases
Solution Approach 1:
The patent controls burn rate by adjusting formulation parameters including oxidizer particle size distribution, suppressant concentration, and binder composition. These parameter changes enable precise control of combustion characteristics to achieve optimal thrust while preventing excessive pressure that could damage the motor case
3Object-affected harmful factors
If burn rate is decreased, then pressure damage risk is reduced, but thrust becomes insufficient
Solution Approach 1:
The patent optimizes the balance between burn rate suppression and thrust generation by carefully adjusting formulation parameters. The oxidizer particle size distribution and suppressant levels are tuned to achieve the minimum burn rate required for sufficient thrust while staying below the threshold for pressure damage
4Reliability
If AP particle size is increased to reduce burn rate, then burn rate control is achieved, but processing problems increase
Solution Approach 1:
The patent uses a specific range of oxidizer particle sizes that balance burn rate control with manufacturability. The formulation incorporates particle size distribution parameters that prevent both excessive burn rates (from fine particles) and processing difficulties (from coarse particles), achieving an optimal middle ground for production
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 dimer fatty diol effectively reduces burn rates, similar to DDI, while minimizing reformulation complexity and costs, maintaining the performance of the solid propellant and offering a more affordable alternative, potentially saving up to $103,000 per 100,000-pound booster motor.
Implementation Method 1
During cure, the DDI reacts with hydroxyl groups of the HTPB to form a reaction product having two urethane linkages
Implementation Method 2
Solid propellants are used in rocket motors to provide thrust for attaining rocket motor propulsion. During combustion, the solid propellant should burn at a controlled and predictable rate
Data Source
AI summary
A precursor formulation comprising, before curing, a hydroxyl-terminated polybutadiene (HTPB) prepolymer or a hydroxyl-terminated polyether (HTPE) prepolymer, an oxidizer, a dimer fatty diol, and an isocyanate curative. A solid propellant comprising a reaction product of the HTPB prepolymer or HTPE prepolymer, the dimer fatty diol, and the isocyanate curative is also disclosed, as is a rocket motor comprising a case and a solid propellant in the case, the solid propellant comprising the reaction product and an oxidizer. A method of reducing a burn rate of a solid propellant is also disclosed.