Hydroxyl Amine Rocket Motor Staged Combustion

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Solution Overview

Problem

Current rocket motor designs face challenges in safety, thrust modulation, toxic combustion products, and maintaining a consistent oxidizer/fuel ratio, with most failing to meet the Insensitive Munitions standard and lacking efficient thrust control.

Innovation Solution

A staged combustion hybrid rocket motor design utilizing a hydroxyl amine based liquid oxidizer, such as hydroxyl amine nitrate (HAN), which is decomposed by a catalyst to produce a stoichiometrically oxygen-rich gas for combustion, allowing for adjustable thrust and reduced toxicity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional hybrid rocket motor design is used, then the motor can operate with simple structure, but it is difficult to maintain consistent oxidizer/fuel ratio during combustion

Engineering Contradiction:
Improveoxidizer/fuel ratio consistencyVSAvoidmotor structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent employs a deformable fuel grain structure that dynamically adjusts its geometry during combustion to maintain consistent oxidizer/fuel ratio. The fuel grain is designed with flexible or collapsible elements that change shape as propellants are consumed, compensating for the changing chamber volume and maintaining proper mixing ratios throughout the burn cycle.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes physical parameters of the fuel grain structure during operation. The fuel grain transitions from an initial rigid configuration to a deformed configuration that adapts to combustion conditions, altering its effective surface area and geometry to maintain optimal oxidizer/fuel ratio consistency throughout the combustion process.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If thrust modulation mechanism is added to modify thrust during operation, then thrust control capability is improved, but the engineering complexity and cost increase significantly

Engineering Contradiction:
Improvethrust modulation capabilityVSAvoidengineering complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The fuel grain structure serves dual functions: it acts as both the propellant source and the thrust modulation mechanism. By designing the fuel grain with self-deforming capabilities that automatically adjust to combustion conditions, the system achieves thrust modulation without requiring separate complex control mechanisms, valves, or additional engineering systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The deformable fuel grain structure performs multiple functions simultaneously: it provides the fuel supply, maintains oxidizer/fuel ratio consistency, and enables thrust modulation. This multi-functional design eliminates the need for separate dedicated thrust control mechanisms, reducing overall system complexity while achieving adaptability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If high-performance propellants are used to improve rocket performance, then Specific Impulse is improved, but the hazard classification increases and safety decreases

Engineering Contradiction:
ImproveSpecific ImpulseVSAvoidsafety
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the propellants, using hydroxyl amine nitrate (HAN) as an oxidizer with lower hazard classification compared to traditional high-performance oxidizers. This compositional change maintains acceptable Specific Impulse performance while improving safety characteristics and reducing hazard classification for handling and storage.

Inventive Principle:
Principle #35Parameter changes

4Object-affected harmful factors

If conventional rocket motor design is used, then the motor can be simple in structure, but it releases toxic and corrosive combustion products that damage the launch vehicle and pose health risks

Engineering Contradiction:
Improvetoxic combustion productsVSAvoidmotor design complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent employs propellants that produce inert or less toxic combustion products. By selecting hydroxyl amine nitrate as the oxidizer and appropriate fuel combinations, the combustion process generates exhaust products with reduced toxicity and corrosiveness, creating a safer environment for the launch vehicle and ground personnel without requiring complex exhaust treatment systems.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

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 design achieves a safer, low-hazard propulsion system with improved Specific Impulse and flexibility in thrust control, reducing environmental and health risks while maintaining high performance.

Implementation Method 1

the injector including a catalyst operably positioned between said first chamber and second chamber, the catalyst being arranged to react with the fluid oxidizer to produce a gaseous mixture containing at least one product resulting from decomposition of said fluid oxidizer

Methodology Applied
Scientific EffectCatalysis: Catalysis

Implementation Method 2

the catalyst being arranged to react with the fluid oxidizer to produce a gaseous mixture containing at least one product resulting from decomposition of said fluid oxidizer

Methodology Applied
Scientific EffectDecomposition: Decomposition (biological)

Implementation Method 3

a flow controller coupled to the injector for controlling the flow of the gaseous mixture into said first chamber

Methodology Applied
Scientific EffectFlow control:

Implementation Method 4

a first chamber positioned in the first end portion of the housing, said first chamber being adapted to contain solid combustible materials

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP2158395B1Hydroxy amine based staged combustion hybrid rocket motor
Publication Date: 2018.06.20 RAYTHEON CO
  • EP2158395B1 patent drawingFigure 1
  • EP2158395B1 patent drawingFigure 2(a)~2(b)

AI summary

A new rocket motor assembly configuration is disclosed. Amine based oxidizer is decomposed in the presence of a metallic catalyst to generate an oxygen rich hot gas stream. The hot gas stream is used to trigger a Magnesium based solid fuel in the combustion chamber. The thrust of the rocket motor may be regulated at multiple points. This design thus offers an IM compliant, thrust-adjustable rocket motor that is of a low hazard classification without compromising its performance.