Variable Position Airfoil for Stealth and Agility Tradeoff
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Solution Overview
Problem
Existing aircraft designs face a tradeoff between agility and radar cross-section, as flight surfaces and airfoils that improve agility also increase the aircraft's radar visibility, leading to suboptimal performance in both areas.
Innovation Solution
The implementation of a movable airfoil system that can rotate between multiple indexed positions, allowing the airfoil to change its orientation from a horizontal to a vertical position or vice versa, thereby adjusting its radar cross-section and agility characteristics as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the airfoil is positioned vertically to improve agility, then maneuverability is improved, but radar cross-section increases
Solution Approach 1:
The patent implements a movable airfoil system that can dynamically change its orientation between vertical and horizontal positions. The airfoil is coupled to the fuselage via a hinge member that allows rotation, enabling the aircraft to adapt its configuration based on mission requirements - vertical position for enhanced agility during maneuvering phases, and horizontal position for reduced radar cross-section during stealth phases.
Solution Approach 2:
The invention changes the geometric parameter of the airfoil orientation angle to resolve the contradiction. By adjusting the airfoil's angular position relative to the fuselage (vertical vs. horizontal), the system optimizes both agility and radar cross-section characteristics at different operational phases, transforming a fixed-parameter design into a variable-parameter solution.
2Object-affected harmful factors
If the airfoil is positioned horizontally to reduce radar cross-section, then stealth performance is improved, but agility deteriorates
Solution Approach 1:
The movable airfoil system allows the aircraft to dynamically transition between horizontal and vertical configurations. During stealth missions requiring low radar cross-section, the airfoil is positioned horizontally; when agility is required for combat maneuvers, the airfoil rotates to a vertical position, providing optimal performance for each operational phase.
Solution Approach 2:
The system varies the airfoil's geometric orientation parameter to balance stealth and agility requirements. By changing the airfoil's angular position from horizontal (low radar cross-section) to vertical (high agility), the aircraft can optimize its performance characteristics based on real-time mission requirements.
3Stability of the object's composition
If fixed vertical tail is used to provide yaw control, then yaw stability is maintained, but radar cross-section increases
Solution Approach 1:
The patent replaces the fixed vertical tail with a movable airfoil system that can be positioned vertically to provide yaw control when needed. During stealth phases, the airfoil is positioned horizontally, eliminating the vertical surface that would increase radar cross-section, while aerodynamic control surfaces on the wing provide alternative yaw control authority.
Solution Approach 2:
The movable airfoil serves multiple functions depending on its position: it can operate as a vertical stabilizer and rudder when positioned vertically for yaw control, or as a low-profile horizontal surface when positioned for stealth. This multi-functional design eliminates the need for a dedicated fixed vertical tail that would always increase radar cross-section.
Data Source
Figure 1
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Figure 4A~5B
AI summary
An aircraft includes an airfoil and a hinge member to rotatably couple the airfoil to a structure of an aircraft. The hinge member defines at least a portion of a rotational axis. The aircraft also includes an indexing mechanism coupled to the airfoil and configured to, in a first state, inhibit rotation of the airfoil about the rotational axis, and in a second state, to permit rotation of the airfoil about the rotational axis between a first position and a second position that is angularly indexed relative to the first position. The aircraft further includes an actuator to selectively change a state of the indexing mechanism from the first state to the second state, from the second state to the first state, or both.