Aircraft Air Inlet with Pivotable Guide Plates

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Solution Overview

Problem

Existing air inlet designs for aircraft engines face a trade-off between high engine performance and low radar signature, as straight-line airflow enhances performance but increases radar visibility, while curved inlets reduce radar signature but may impair airflow and require heavy, maintenance-intensive coatings.

Innovation Solution

An air inlet device with pivotable air guide arrangements that can switch between linear and curved courses, allowing for selective optimization of radar signature and engine performance based on mission requirements, using a frame, centre tube, and pivot plates connected by intersecting pivot axes to control airflow direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the air inlet has a straight-line course to guide air directly to the engine, then engine performance is improved, but radar signature increases

Engineering Contradiction:
Improveengine performanceVSAvoidradar signature
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The patent applies the dynamics principle by making the air guide arrangements movable and adjustable. The air guides can be positioned in different configurations (straight-line course for performance, curved course for radar reduction) and can be adjusted during operation. This allows the system to dynamically switch between optimizing engine performance and reducing radar signature based on mission requirements, rather than being fixed in a single configuration.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If the air inlet has a curved course to reduce radar signature, then radar visibility is reduced, but engine performance deteriorates

Engineering Contradiction:
Improveradar signatureVSAvoidengine performance
Core Design Contradiction:
Object-affected harmful factorsVSPower

Solution Approach 1:

The air guides are designed as movable components that can be adjusted between different positions. When radar signature reduction is prioritized, the air guides can be positioned to create a curved airflow path. When engine performance is prioritized, the air guides can be repositioned to create a straight-line airflow path. This dynamic adjustability resolves the contradiction by allowing the system to optimize for either parameter depending on operational needs.

Inventive Principle:
Principle #15Dynamics

3Object-affected harmful factors

If a coating is applied to the air inlet surface to absorb electromagnetic waves, then radar signature is reduced, but weight and maintenance effort increase

Engineering Contradiction:
Improveradar signatureVSAvoidweight
Core Design Contradiction:
Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The patent extracts the radar signature reduction function from a separate coating layer and integrates it into the structural design of the air inlet device itself. By using movable air guides that can be positioned to block or deflect radar waves, the system achieves radar signature reduction through geometry and positioning rather than through material properties. This eliminates the need for additional coating materials, thereby avoiding the associated weight penalty and maintenance requirements.

Inventive Principle:
Principle #2Taking out (Extraction)

4Object-affected harmful factors

If a coating is applied to the air inlet surface to absorb electromagnetic waves, then radar signature is reduced, but maintenance effort increases

Engineering Contradiction:
Improveradar signatureVSAvoidmaintenance effort
Core Design Contradiction:
Object-affected harmful factorsVSEase of repair

Solution Approach 1:

The patent removes the dependency on coatings for radar signature reduction by implementing a mechanical solution using movable air guides. These guides can be repositioned or adjusted to achieve radar signature reduction without requiring any surface coatings. Since the solution is structural and mechanical rather than material-based, there are no coatings to wear away, crack, or require refreshing, thereby eliminating the associated maintenance burden.

Inventive Principle:
Principle #2Taking out (Extraction)

5Adaptability or versatility

If the air guide arrangements are made movable to switch between linear and curved courses, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improveoperational flexibilityVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The air inlet device is segmented into multiple independent air guide arrangements, each capable of being individually positioned or adjusted. This segmentation allows the system to achieve complex airflow patterns and radar signature reduction through the coordinated positioning of simpler individual components, rather than requiring a single complex movable structure. Each air guide can be independently controlled, providing adaptability while keeping individual component complexity manageable.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4180639B1Air inlet device for an inlet duct to an engine of an aircraft
Publication Date: 2024.03.27 AIRBUS DEFENCE & SPACE GMBH
  • EP4180639B1 patent drawingFigure 1
  • EP4180639B1 patent drawingFigure 2~3
  • EP4180639B1 patent drawingFigure 4~5

AI summary

An air inlet device (100) for an air inlet of an aircraft is described. The air inlet device (100) has a plurality of air guide arrangements (130). An air guide arrangement (130) has an inlet plate (131), an outlet plate (139), and a plurality of pivot plates (133, 135, 137) arranged therebetween. The outlet plate and the pivot plates can be rotated about a central axis of the air inlet device by adjustment rings, so that the air guide arrangement (130) is transitioned from a linear state to a curved state, and vice versa. The air inlet device allows for selective switching between a state with low radar signature and a state with high performance of an engine.