Selectable Ramjet Propulsion System for Missile Thrust Control
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Solution Overview
Problem
Ramjet missiles require a conventional rocket boost phase to reach high supersonic speeds, but the ramjet phase delivers lower thrust over an extended period, making it less effective for short-range missions where the rocket can accelerate and intercept targets faster.
Innovation Solution
A selectable ramjet propulsion system that includes a gas generator adjacent to a booster with a frangible diaphragm, allowing the system to initiate the gas generator fuel supply and rupture the diaphragm based on the target distance, enabling the engine to burn both ramjet fuel and booster propellant for short-range missions to achieve higher thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional rocket boost phase is used to reach high supersonic speeds, then the missile can achieve high initial velocity, but the thrust level is excessively high and fuel consumption is inefficient for longer range missions
Solution Approach 1:
The propulsion system is segmented into distinct phases: an initial rocket boost phase using stored propellant to reach supersonic speeds, followed by a ramjet phase that uses atmospheric oxygen for combustion. This segmentation allows the missile to use the high-thrust rocket only when necessary for rapid acceleration, then transition to the more fuel-efficient ramjet for sustained flight and long-range missions.
2Use of energy by moving object
If the ramjet phase is used for propulsion, then fuel consumption efficiency is improved, but the thrust level is lower and acceleration time is extended
Solution Approach 1:
The system performs preliminary action by using the rocket booster to accelerate the missile to supersonic speeds before the ramjet phase begins. This preliminary high-thrust acceleration ensures the missile reaches the minimum speed required for effective ramjet operation, after which the transition to ramjet propulsion provides sustained efficient flight without excessive acceleration time.
3Loss of time
If the rocket only propulsion mode is used for short range missions, then the time to intercept target is reduced, but the fuel consumption efficiency is lower compared to ramjet operation
Solution Approach 1:
The propulsion system is made dynamic and adaptable to mission requirements. For short-range missions, the system operates in rocket-only mode to minimize time to target. For long-range missions, the system transitions to ramjet operation to maximize fuel efficiency. The ability to dynamically adjust the propulsion mode based on the specific mission parameters resolves the contradiction between speed and energy efficiency.
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
This system allows for increased thrust and improved performance for short-range missions by applying ramjet impulse during the boost phase, reducing time to target and enhancing Mach number, while conserving fuel for longer-range capabilities.
Implementation Method 1
A frangible diaphragm is disposed between the gas generator and the booster
Implementation Method 2
A booster propellant contained within the booster is ignited
Data Source
AI summary
A selectable ramjet propulsion system for propelling a rocket or missile includes a gas generator adjacent a booster. A frangible diaphragm is disposed between the gas generator and the booster. The booster and fuel gas generator can be operated in normal sequence, or operated at the same time in order to increase the thrust produced for short-range missions. A logic circuit contained on the rocket or missile determines a time to rupture the frangible diaphragm based on whether or not the distance to the target exceeds a threshold distance.