Pellet-Loaded Multiple-Impulse Rocket Motor

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Solution Overview

Problem

Existing solid fuel rocket motors for attitude control thrusters lack efficient multiple-impulse capabilities due to limitations in propellant burn rate, density, and nozzle pressure, leading to suboptimal thrust control and impulse delivery.

Innovation Solution

A pellet-loaded multiple-impulse rocket motor design featuring independent combustion chambers with separate igniters and burst disks, allowing for sequential ignition and controlled pressure release, utilizing solid fuel pellets with varying compositions and inhibitor coatings to optimize thrust and impulse delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single propellant charge is used in a common combustion chamber, then the motor structure is simple, but the thrust control precision and impulse delivery are limited

Engineering Contradiction:

Improvethrust control precisionVSAvoidcombustion chamber structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The single propellant charge is divided into multiple separate propellant charges, each in its own combustion chamber. This segmentation allows independent control of each charge's burn rate and ignition timing, enabling precise thrust control while maintaining a relatively simple overall motor structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from a static single-chamber design to a dynamic multi-chamber configuration where each combustion chamber can be independently ignited and controlled. This enables variable thrust output by selectively igniting different combinations of propellant charges.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If propellant charges are separated by burst disks, then sequential ignition is enabled, but the response time between impulses increases

Engineering Contradiction:

Improvesequential ignition controlVSAvoidimpulse delivery interval

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

Multiple propellant charges are pre-loaded into the motor during manufacturing, with igniters positioned for rapid sequential activation. This preliminary preparation eliminates the need for complex in-flight propellant loading mechanisms and reduces the time between impulses.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mechanical burst disk separation system is replaced with a controlled ignition timing system where electrical igniters can be activated in rapid sequence without mechanical barriers. This substitution significantly reduces the impulse delivery interval while maintaining sequential control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Force

If multiple propellant charges are ignited simultaneously, then the total thrust is high, but sympathetic ignition occurs and thrust control is lost

Engineering Contradiction:

Improvetotal thrustVSAvoidthrust control reliability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The propellant charges are segmented into separate combustion chambers with independent igniters, allowing selective ignition of individual charges or groups. This prevents sympathetic ignition by isolating each charge's combustion zone while enabling controlled simultaneous ignition of multiple charges for high thrust when needed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system incorporates monitoring of combustion conditions in each chamber, allowing the control system to adjust ignition timing and intensity based on real-time feedback. This prevents runaway combustion and maintains thrust control reliability even when multiple charges are ignited.

Inventive Principle:

Principle #23Feedback

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

Enables precise control over thrust and impulse delivery by allowing independent ignition of combustion chambers, enhancing the motor's ability to provide multiple impulses with finer control over thrust profiles and reducing sympathetic ignition risks.

Implementation Method 1

solid fuel pellets with varying compositions and inhibitor coatings to optimize thrust and impulse delivery

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

separate igniters and burst disks, allowing for sequential ignition and controlled pressure release

Methodology Applied

Scientific EffectPressure release: Depressurisation

Data Source

PatentUS8667776B2Pellet-loaded multiple impulse rocket motor

Publication Date: 2014.03.11 RAYTHEON CO

AI summary

There is disclosed an apparatus which may include a common nozzle and a plurality of combustion chambers coupled to the nozzle. Each of the plurality of combustion chambers may include a case, a solid fuel propellant charge in the form of a plurality of fuel pellets, and an igniter disposed to ignite the propellant charge. Each of the plurality of combustion chambers may also include a pellet retainer disposed to retain unignited fuel pellets within the case and a burst disk disposed between the propellant charge and the nozzle. Each burst disk may adapted to rupture when the associated propellant charge is ignited and to not rupture when a propellant charge of any of the other combustion chambers is ignited.