Ramjet Variable Geometry for Booster-Free Supersonic Launch
Solution Overview
Problem
Conventional ramjet engines require a separate booster motor or vehicle to accelerate them to the minimum operating speed, which increases the size and complexity of the engine/vehicle system.
Innovation Solution
The high-speed-launch ramjet boost (HSLRB) engine features a variable geometry (VG) nozzle and either a fixed geometry (FG) inlet or a VG inlet, allowing it to be ignited at supersonic speeds and generate enough excess thrust to separate from a high-speed aircraft at ≥2 Mach without a conventional booster.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional ramjet engine is used with fixed geometry inlet and nozzle, then the engine structure is simple, but a separate booster motor is required to accelerate the engine to minimum operating speed, increasing overall vehicle mass and size
Solution Approach 1:
The patent applies variable geometry to both the inlet and nozzle of the ramjet engine. The inlet includes movable ramps that can be adjusted to optimize airflow at different Mach numbers, while the nozzle includes an adjustable expansion ratio to maintain efficient exhaust flow across a wide speed range. This dynamic adaptability allows the engine to operate effectively from subsonic speeds through supersonic speeds without requiring a separate booster, thereby reducing overall vehicle mass while maintaining manageable structural complexity
Solution Approach 2:
The patent changes the geometric parameters of the inlet and nozzle based on operating conditions. The inlet capture area and ramp angles are varied to optimize compression at different Mach numbers, while the nozzle expansion ratio is adjusted to match ambient pressure conditions. This parameter adaptation enables the engine to generate sufficient thrust across the entire operating envelope, eliminating the need for a booster motor and reducing vehicle mass
2Ease of manufacture
If a conventional ramjet engine with fixed geometry is used, then the manufacturing is simpler, but the engine cannot operate efficiently over a wide range of speeds and altitudes
Solution Approach 1:
The patent implements variable geometry mechanisms in both the inlet and nozzle. The inlet features movable compression ramps that can be positioned at different angles to optimize airflow capture and compression at various Mach numbers. The nozzle incorporates an adjustable expansion section that can be reconfigured to match different ambient pressure conditions. These dynamic adjustments enable efficient operation across a wide speed and altitude range, from subsonic to hypersonic regimes
Solution Approach 2:
The inlet is divided into multiple adjustable ramps that can be independently controlled, allowing fine-tuned optimization of airflow at different operating conditions. The nozzle is segmented into adjustable expansion sections that can be reconfigured based on altitude and speed. This segmentation provides flexibility in adapting to various flight conditions while maintaining a manageable manufacturing complexity through modular design
3Speed
If a separate booster motor is added to accelerate the ramjet to operating speed, then the ramjet can be launched from subsonic speeds, but the vehicle size and logistical footprint increase
Solution Approach 1:
The variable geometry inlet and nozzle enable the ramjet to generate sufficient excess thrust at low speeds without a booster. The inlet can be configured to maximize airflow capture at subsonic and low-supersonic speeds, while the nozzle adjustment optimizes exhaust momentum. This dynamic adaptation allows the engine to accelerate the vehicle from standstill or low-speed launch conditions, eliminating the need for a separate booster motor and reducing vehicle volume
Solution Approach 2:
The ramjet engine is designed to be self-accelerating through its variable geometry systems. The inlet and nozzle adjustments enable the engine to generate the necessary thrust to overcome drag and accelerate the vehicle to its operating speed range. This self-service capability eliminates the dependency on external booster systems, reducing both vehicle size and logistical requirements
4Ease of operation
If fixed geometry inlet and nozzle are used, then the device is easier to operate, but excess thrust is insufficient at low speeds for separation and acceleration
Solution Approach 1:
The variable geometry inlet and nozzle are controlled through automated systems that adjust the geometry based on measured flight conditions such as Mach number and altitude. This automated control maintains optimal performance across the operating envelope without requiring complex manual intervention. The system provides sufficient excess thrust at low speeds by configuring the inlet and nozzle for maximum efficiency, enabling successful separation and acceleration while maintaining relative operational simplicity through automation
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 HSLRB engine achieves significant reductions in overall vehicle mass and size, launch costs, and logistical footprint, while offering more adaptable mission profiles and flexible basing/launch location options.
Implementation Method 1
Thrust for the ramjet is produced by passing hot exhaust generated from the combustion of a fuel through a jet nozzle. The nozzle accelerates the flow, and the reaction to this acceleration produces thrust.
Implementation Method 2
the combustion must occur at a pressure higher than the pressure at the nozzle exit
Implementation Method 3
In a ramjet, this needed high relative pressure is produced by 'ramming' external air into the combustor using the forward speed of the vehicle
Data Source
AI summary
A method of propulsion includes providing a high-speed-launch ramjet boost (HSLRB) stage and HSLRB engine attached to a launch aircraft providing a speed ≥1.5 Mach. The HSLRB engine includes a combustion system and inlet(s) for air flow to the fuel injectors. A variable geometry (VG) nozzle having a nozzle actuator exhausts gas from combustion. A processor receives sensing signals from sensor(s) during flight that provides control signals to the nozzle actuator for dynamically controlling an aperture size of the VG nozzle, and if the inlet is a VG inlet to an inlet actuator to dynamically control the VG inlet shape. The HSLRB engine is ignited while attached to the aircraft at 1.5 to 1.99 Mach if assisting the aircraft to accelerate to 2.0 Mach, or at a speed of ≥2.0 Mach if the aircraft can accelerate to 2.0 Mach autonomously, then the HSLRB stage is separated from the aircraft.