Multi-Pulse Rocket Motor With Electric-Field Ignition

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional multi-pulse rocket motors face challenges such as complicated and costly barrier and igniter systems, potential nozzle clogging, and limited to two pulses, which can lead to combustion instability and manufacturing difficulties.

Innovation Solution

A rocket motor with an electrically operated propellant initiator featuring a pair of electrodes, including a ground plane electrode and an ignition electrode, configured to concentrate an electric field for igniting electrically operated propellant, ensuring operatively isolated and controlled combustion of propellant grains, thereby eliminating the need for complex barriers and enabling multiple pulses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional barrier and igniter systems are used to separate propellant grains in multi-pulse rocket motors, then propellant isolation is achieved, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvepropellant isolationVSAvoidbarrier and igniter system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the complex barrier system entirely by using electrically operated propellant initiators with ground plane electrodes that directly ignite propellant grains without requiring physical separation barriers. This extracts the barrier component from the system while maintaining propellant isolation through controlled electrical ignition.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The ground plane electrode serves multiple functions: it provides electrical connection for ignition, acts as a barrier to prevent combustion gas transfer between pulses, and enables controlled initiation of individual propellant grains. This multi-functional approach eliminates the need for separate barrier and igniter systems.

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

2Reliability

If conventional barriers are used to separate propellant grains, then propellant isolation is achieved, but nozzle clogging and combustion instability occur due to barrier ejection or inversion

Engineering Contradiction:
Improvepropellant isolationVSAvoidnozzle clogging and combustion instability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent eliminates the barrier component that causes ejection and inversion problems by using electrically operated initiators with ground plane electrodes. This removes the source of harmful factors while maintaining the necessary propellant isolation function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The ground plane electrode acts as an intermediary that provides both electrical connection for ignition and physical separation between propellant grains without the drawbacks of conventional barriers. It mediates between the need for isolation and the need to avoid nozzle clogging.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If conventional multi-pulse rocket motors are designed with barrier systems, then two-pulse operation is achieved, but the system is limited and cannot easily accommodate more pulses

Engineering Contradiction:
Improvepulse number flexibilityVSAvoidbarrier system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The ground plane electrode design provides a universal solution that can accommodate any number of pulses by simply adding more electrodes and propellant grains. The same basic structure scales from two pulses to multiple pulses without requiring fundamentally different barrier configurations.

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

Solution Approach 2:

The patent uses segmented propellant grains with individual ground plane electrodes for each grain. This segmentation allows independent control of each pulse while using the same basic structural unit, making it easy to add or remove pulses as needed.

Inventive Principle:
Principle #1Segmentation

4Ease of operation

If conventional igniter systems are used for each propellant pulse, then individual pulse ignition is achieved, but manufacturing cost and complexity increase

Engineering Contradiction:
Improveindividual pulse ignition controlVSAvoidmanufacturing cost and complexity
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The ground plane electrode serves as both the ignition source and the barrier structure, eliminating the need for separate igniter components. This universal component reduces manufacturing steps and costs while maintaining individual pulse ignition control capability.

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

Solution Approach 2:

The patent merges the barrier function and igniter function into a single ground plane electrode component. This consolidation reduces the number of parts that need to be manufactured and assembled, thereby reducing manufacturing complexity and cost.

Inventive Principle:
Principle #5Merging (Combining)

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 provides efficient, controlled ignition and isolation of propellant grains, reducing manufacturing complexity and costs, while allowing for multiple propulsion pulses without nozzle clogging, enhancing operational reliability and flexibility.

Implementation Method 1

at least one pair of electrodes arranged to ignite the electrically operated propellant, the at least one pair of electrodes including a ground plane electrode and an ignition electrode at which an electric field is concentrated to ignite the electrically operated propellant

Methodology Applied
Scientific EffectElectric field concentration: Electric Field

Implementation Method 2

initiate combustion of the at least one propellant grain

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP4251871B1Multi-pulse solid propellant rocket motor and ignition method
Publication Date: 2025.08.13 RAYTHEON CO
  • EP4251871B1 patent drawingFigure 1
  • EP4251871B1 patent drawingFigure 2~3
  • EP4251871B1 patent drawingFigure 4~7

AI summary

A rocket motor has an electrically operated propellant initiator for a propellant grain that includes an electrode arrangement configured to concentrate an electric field at an ignition electrode for igniting an electrically operated propellant. The rocket motor includes a combustion chamber containing at least one propellant grain and an electrically operated propellant initiator operatively coupled to the propellant grain to initiate combustion of the propellant grain. The electrically operated propellant initiator includes the electrically operated propellant and at least one pair of electrodes configured to ignite the electrically operated propellant. The pair of electrodes includes a ground plane electrode and an ignition electrode. When an electrical input is applied to the electrically operated propellant initiator, the electric field is concentrated at the ignition electrode to ignite the electrically operated propellant at the location where the ignition electrode is arranged.