Stealth Aircraft Air Inlet Closure for Variable Intake and Low RCS
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Solution Overview
Problem
Existing air intake designs for stealth aircraft often compromise between required air inlet volumes and low radar cross-sections, leading to increased radar detectability and drag, which negatively impacts aircraft performance and survivability.
Innovation Solution
An air inlet arrangement with an expansible closure device that can open flexibly in multiple directions, utilizing auxetic structures and radar-absorbing materials to minimize radar cross-section and air resistance, maintaining supersonic capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the air inlet volume is increased to meet cooling requirements, then the cooling performance is improved, but the radar cross-section increases making the aircraft more detectable
Solution Approach 1:
The patent employs a movable closure device that can dynamically adjust the air inlet opening area. The closure device transitions between different positions (first position for maximum air intake, second position for reduced air intake) to adapt to varying operational requirements. This dynamic adjustment allows the system to optimize between cooling performance and radar cross-section reduction based on real-time needs.
Solution Approach 2:
The patent changes the geometric parameters of the air inlet by moving the closure device to different positions. When the closure device is in the first position, the air inlet opening area is maximized for optimal cooling. When moved to the second position, the opening area is reduced to minimize radar cross-section. This parameter change enables the system to resolve the contradiction between cooling requirements and stealth characteristics.
2Productivity
If the air inlet opening area is increased to improve air intake, then the cooling efficiency is improved, but the drag coefficient increases affecting maximum speed
Solution Approach 1:
The movable closure device enables dynamic control of the air inlet opening area. During phases requiring high air intake (such as high-speed flight or high power settings), the closure device is positioned to maximize the opening area for optimal cooling and air supply. During phases where speed is prioritized, the closure device reduces the opening area to minimize drag, thus resolving the contradiction between air intake efficiency and maximum speed.
3Object-affected harmful factors
If a closure device is added to control air intake, then the ability to reduce radar cross-section is improved, but the device complexity increases
Solution Approach 1:
The closure device is designed as a movable flap or panel that can be integrated into the air inlet structure. This flexible component can be positioned in different locations (first position for maximum intake, second position for reduced intake) and can be made from materials that maintain aerodynamic smoothness. The design uses relatively simple mechanical actuation mechanisms rather than complex multi-component systems, thereby reducing overall device complexity while still achieving radar cross-section reduction.
4Object-affected harmful factors
If the closure device is positioned to minimize radar cross-section, then the stealth performance is improved, but the air intake volume is reduced
Solution Approach 1:
The system uses dynamic positioning of the closure device to resolve the contradiction between stealth performance and air intake volume. When stealth is the priority (such as during low-speed cruise or weapon delivery), the closure device is positioned in the second position to minimize radar cross-section. When air intake volume is needed (such as during high-power operation or high-speed flight), the closure device moves to the first position to maximize air intake. This dynamic adjustment allows the system to optimize performance based on operational context.
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 maintains low radar cross-section and air resistance, ensuring high performance and stealth properties while allowing flexible air intake without significantly affecting maximum speed or drag coefficient.
Implementation Method 1
EP 3 595 333 A1 deals with a MEMS (microelectromechanical system) device with a membrane that is configured to vibrate and has an auxetic structure at least in sections. The membrane of the MEMS device is configured to expand in at least a first lateral direction when vibrating, wherein the auxetic structure is configured to expand the membrane in a second direction as a result of the expansion of the membrane in the first direction, and/or wherein the auxetic structure is configured to increase a thickness of the membrane as a result of the expansion in the first direction.
Implementation Method 2
There are various ways to reduce detectability by radar systems, such as reducing the radar cross section (RCS), using radar absorbing material (RAM) and/or radar absorbing structures (RAS).
Data Source
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AI summary
An air inlet arrangement (10) for a low-observable vehicle (1), in particular for a stealth aircraft, is provided with an inlet opening (12) and with a closure device (10) which closes the inlet opening (12) in a closed state (C) and which has at least one expansion section (23), wherein the at least one expansion section (23) is configured to be expansible in at least two spatial directions (X, Y, Z), and a vehicle (1), in particular a stealth aircraft, with at least one such air inlet arrangement (10).