Variable Thrust Solid Rocket Motor via Overlapping Grain Ignition
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Solution Overview
Problem
Solid propellant rocket motors lack the ability to control preselected thrust, velocity, and trajectory, as once ignited, the propellant burns to completion, limiting their multi-stage operation and requiring simultaneous or sequential ignition of stages, which restricts flexibility in achieving desired flight paths and decoy missile simulations.
Innovation Solution
A method and apparatus for controlling multiple solid propellant motor grains with overlapping combustion, where the ignition of subsequent stages is timed relative to the first stage to achieve a desired mass flow pattern, allowing for variable thrust and velocity control through ignition timing and grain selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If solid propellant rocket motor uses traditional single-stage or pulse multi-stage ignition, then the motor can achieve simple operation and reliable combustion, but it cannot control preselected thrust, velocity, and trajectory with flexibility
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple propellant grains with different burn rates and masses before launch. The bus computer calculates and stores optimal ignition timing sequences for each grain based on desired trajectory and velocity profiles. This allows the system to achieve flexible thrust control without complex real-time adjustments during flight, as all control parameters are predetermined and loaded before deployment.
Solution Approach 2:
The patent implements dynamics by enabling continuous variation of thrust profiles through selective ignition of multiple propellant grains with different characteristics. Instead of fixed single-stage or simple pulse operation, the system dynamically adjusts mass flow rate and thrust by igniting specific grains at calculated times based on real-time flight conditions and desired trajectory, achieving adaptive control throughout the flight envelope.
2Productivity
If solid propellant rocket motor enables multiple decoy launches from bus, then the missile can simulate attack on multiple targets, but it becomes difficult to control individual decoy trajectories and velocity profiles
Solution Approach 1:
The patent applies segmentation by dividing the total propellant mass into multiple separate grains, with each grain capable of independent ignition. Each grain represents a discrete propellant unit that can be individually controlled to produce specific thrust profiles. This segmentation allows the bus to launch multiple decoys with different trajectories and velocity profiles by selectively igniting different grains at different times, achieving both high productivity and individual control.
Solution Approach 2:
The patent implements parameter changes by varying the ignition timing, duration, and sequence of multiple propellant grains to achieve different thrust profiles. The bus computer calculates optimal ignition parameters for each grain based on desired decoy trajectories, allowing precise control of mass flow rate, velocity changes, and flight paths for each launched decoy while maintaining the ability to launch multiple units from the same bus.
3Reliability
If solid propellant grain burns to completion once ignited, then the combustion process is simple and reliable, but the ability to stop and restart combustion is lost
Solution Approach 1:
The patent applies segmentation by using multiple separate propellant grains instead of a single continuous grain. Each grain is independently ignitable and can be controlled separately. This allows the system to achieve start-stop-restart capability by igniting, exhausting, and then igniting subsequent grains as needed, while maintaining reliable combustion within each individual grain since each grain still burns to completion when ignited.
Solution Approach 2:
The patent implements continuity of useful action by arranging multiple propellant grains in a sequence where subsequent grains can be ignited before previous grains complete combustion. This creates overlapping combustion periods that provide continuous thrust capability. The system maintains reliable combustion in each grain while achieving overall continuous and controllable thrust production through the sequence of grain ignitions.
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 velocity profiles, allowing for preselected trajectory and velocity settings, enhancing the capability of multi-stage rocket motors to simulate decoy missile launches with varied flight paths and angles, improving the simulation of actual warheads by managing mass discharge profiles.
Implementation Method 1
The grains are ignited so that there is overlap in combustion. After ignition of a first stage, ignition of subsequent stages is timed to achieve a desired mass flow pattern.
Data Source
AI summary
A multiple-stage solid rocket motor is operated in a manner designed to control its mass discharge profile. This is accomplished by providing means for igniting one stage and then igniting a subsequent stage while the first continues to burn.