Forward-Swept Finocyl Grain for Solid Rocket Motor Thrust Tailoring

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Solution Overview

Problem

Conventional solid rocket motor propellant grain configurations, such as finocyl grains, face limitations in achieving high propellant volumetric loading density and flexibility in tailoring thrust profiles to meet diverse mission-specific requirements.

Innovation Solution

A propellant grain configuration featuring a monolithic, coaxial, case-bonded solid rocket motor with a plurality of deep, forward-swept, longitudinal fin cavities circularly patterned about an axial conical and/or cylindrical cavity, allowing for increased flexibility in thrust profile tailoring and high volumetric loading density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional reverse-swept finocyl grain configurations are used, then structural simplicity and ease of manufacture are maintained, but propellant volumetric loading density and thrust profile tailoring flexibility are limited

Engineering Contradiction:
Improvethrust profile tailoring flexibilityVSAvoidgrain configuration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent inverts the conventional reverse-swept fin geometry by using forward-swept fins instead. This inversion fundamentally changes the regression pattern characteristics, enabling superior thrust profile tailoring flexibility while maintaining the simple monolithic finocyl structure. The forward-swept configuration allows the burn surface to evolve differently during combustion, providing enhanced control over thrust profiles without increasing structural complexity.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent employs parameter changes by varying the sweep angle, fin depth, and circular pattern arrangement of the fins. These parameter modifications to the grain geometry enable optimization of both volumetric loading density and thrust profile characteristics. By adjusting these geometric parameters, the design achieves high adaptability for different mission requirements while maintaining manufacturing feasibility.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If deeper fin cavities are implemented to increase volumetric loading density, then propellant loading efficiency improves, but manufacturing complexity and potential grain structural weaknesses increase

Engineering Contradiction:
Improvepropellant volumetric loading densityVSAvoidgrain manufacturing ease
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The forward-swept fin configuration inverts the conventional approach to fin geometry. This inversion allows the fin cavities to be deeper and more complex in shape while actually simplifying the manufacturing process. The forward sweep direction aligns better with conventional casting and machining operations, enabling production of deep fin cavities without proportionally increasing manufacturing difficulty or structural risk.

Inventive Principle:
Principle #13The other way round (Inversion)

3Adaptability or versatility

If forward-swept fin configuration is used to enhance thrust profile flexibility, then adaptability improves, but deviation from conventional designs increases manufacturing risk

Engineering Contradiction:
Improvethrust profile tailoring capabilityVSAvoidmanufacturing familiarity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent achieves enhanced thrust profile flexibility through controlled parameter changes in the fin geometry - specifically the forward sweep angle, fin depth, and circular pattern distribution. These parameter modifications represent evolutionary rather than revolutionary changes, allowing manufacturers to work with familiar processes while achieving new performance capabilities. The parameter adjustments are optimized to balance manufacturing feasibility with enhanced adaptability.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3256711B1Propellant grain for a solid rocket motor
Publication Date: 2020.09.09 DIRECTOR GENERAL DEFENCE RES & DEV ORG
  • EP3256711B1 patent drawingFigure 1a~1b
  • EP3256711B1 patent drawingFigure 2~4
  • EP3256711B1 patent drawingFigure 5a~5b

AI summary

The present disclosure relates to propellant grain configuration in solid rocket motors. In one embodiment, the propellant grain is a case-bonded, forward- swept, deep finocyl grain offering significant flexibility in tailoring burn surface area regression profiles to meet different performance requirements even while allowing for high propellant volumetric loading densities. The grain comprises of two or more longitudinal fin cavities with forward swept leading edges, circular-patterned about an axial cavity.