Propellant Grain Casting Mandrels for Complex Cores and Tailored Thrust

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Solution Overview

Problem

Existing solid propellant propulsion systems face challenges in achieving variable thrust profiles during the flight of a vehicle due to the changing mass and other flight conditions, leading to potential damage or decreased efficiency.

Innovation Solution

A mandrel is used to cast a propellant grain with a design that allows for the formation of non-longitudinal and complex geometries, enabling a core-burning configuration that tailors the burn cycle for desired thrust profiles, and includes features like frangible portions and support structures to maintain geometry and facilitate removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a solid propellant grain is cast around a core to form a hollow core configuration, then the propulsion system can generate thrust through high pressure gas expulsion, but the system cannot achieve variable thrust profiles due to changing mass and flight conditions

Engineering Contradiction:

Improvethrust profile adaptabilityVSAvoidpropulsion system reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The propellant grain is segmented into multiple compartments or sections with different burn rates, allowing independent control of thrust contributions from each segment. This enables variable thrust profiles by activating or adjusting specific segments during flight, resolving the contradiction between thrust adaptability and system reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic thrust control mechanisms such as adjustable nozzle areas, variable port configurations, or controllable ignition sequences that allow the propulsion system to adapt thrust output in real-time based on flight conditions, maintaining reliability while achieving variable thrust profiles.

Inventive Principle:

Principle #15Dynamics

2Shape

If a mandrel is used to cast propellant grain with complex geometries, then non-longitudinal and complex shapes can be formed, but the mandrel removal process becomes more difficult

Engineering Contradiction:

Improvepropellant grain geometry complexityVSAvoidmandrel removal ease

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The mandrel is designed with extraction features such as frangible sections, tapered geometries, or removable core components that allow easy removal after casting. The mandrel may include weak points that break during or after propellant curing, enabling complete extraction without damaging complex propellant geometries, thus resolving the contradiction between shape complexity and manufacturing ease.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

A release agent or coating is applied to the mandrel surface as an intermediary layer between the mandrel and propellant grain. This mediator prevents bonding during curing while allowing precise replication of complex geometries, and facilitates easy mandrel removal without compromising the integrity of complex propellant shapes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the propellant grain is cured around the mandrel to form a hollow core, then a perforation is created for ignition, but the mandrel must be completely removed which complicates the process

Engineering Contradiction:

Improveperforation formation precisionVSAvoidmandrel removal process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The mandrel is designed as a disposable component made from inexpensive, easily removable materials. The mandrel may include frangible sections that break during curing or simple geometric features that allow complete removal through the hollow core without complex extraction mechanisms, resolving the contradiction between perforation precision and process complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The mandrel is pre-configured with removal features such as tapered ends, frangible joints, or predetermined break points before the casting process. This preliminary preparation enables straightforward extraction after curing, maintaining precise perforation formation while simplifying the overall removal process and reducing device complexity.

Inventive Principle:

Principle #10Preliminary action

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 enables the creation of propellant grains with tailored burn cycles, improving thrust management and maintaining structural integrity, thereby optimizing propulsion efficiency and preventing damage from excessive acceleration.

Implementation Method 1

curing the propellant grain around the mandrel

Methodology Applied

Scientific EffectCuring: Photopolymerisation

Data Source

PatentUS12350864B2Systems and methods for casting propellant grain

Publication Date: 2025.07.08 GOODRICH CORP

AI summary

Systems and methods for casting solid propellants include a mandrel for forming geometric features in a perforation of a propellant grain. In various embodiments, the mandrel includes a frangible portion that is removed from the propellant grain after the propellant grain has cured around the mandrel. A second portion of the mandrel may be left behind in the propellant grain. The mandrel may include a support structured disposed in the through hole of the mandrel. The support structure may include a plurality of longitudinal channels for directed exhaust gasses through the mandrel upon ignition of the propellant grain.