Dual Door Stall Correction Mechanism for Wing Flow Control
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Solution Overview
Problem
Current aircraft stall correction systems rely on pilot feedback or sensor-based responses, leading to lag in reacting to wing stall conditions due to the need for information relay from the stall area to decision-makers and subsequent action on control surfaces.
Innovation Solution
A passive stall correction system featuring a hinged upper door and lower door connected by a coupler linkage, where the upper door rotates downward upon airflow separation, causing the lower door to open, allowing airflow through a flap slot to restore laminar flow, without requiring sensors or active actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pilot feedback or sensor-based response systems are used for stall correction, then the system can detect and respond to stall conditions, but there is lag in response due to information relay time
Solution Approach 1:
The upper door is designed to automatically detect airflow separation through suction changes and autonomously trigger the coupler linkage mechanism to open the lower door, eliminating the need for external sensors or pilot intervention. The system serves itself by using the airflow condition directly to actuate the correction mechanism.
Solution Approach 2:
The coupler linkage acts as a mechanical intermediary that directly couples the upper door's motion to the lower door's opening action. This mechanical mediation eliminates information relay delays by creating a direct physical connection between the sensing element (upper door) and the acting element (lower door).
2Loss of time
If a passive stall correction system is used, then response time is reduced, but the device complexity increases with additional doors and linkages
Solution Approach 1:
The upper and lower doors are merged into a single functional unit through the coupler linkage, where the upper door serves as both the sensing element and the actuating element for the lower door. This combination reduces the need for separate sensing and actuation systems.
Solution Approach 2:
The upper door performs multiple functions: it serves as a flow sensor by detecting suction changes, acts as a mechanical actuator through its rotation, and triggers the correction mechanism. This multi-functionality reduces the overall system complexity by eliminating separate components.
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 system provides immediate and automatic stall correction by passively responding to airflow changes, enhancing wing surface airflow effectiveness and control without lag, and returns to a closed position once laminar flow is restored.
Implementation Method 1
Laminar flow over an upper surface of a wing provides suction on an upper door configured for rotation about an upper axis
Implementation Method 2
Laminar flow over an upper surface of a wing provides suction on an upper door
Implementation Method 3
Tension induced by the upper door is reacted in a coupler linkage connected from the upper door to a lower door
Implementation Method 4
Upon interruption of laminar flow due to separation or turbulence over the upper door with resulting reduced suction
Implementation Method 5
the upper door is rotated downward about the upper axis
Implementation Method 6
The lower door is counter-rotated about the lower axis to an open position with the coupler linkage
Implementation Method 7
Air flow from a lower surface of the wing is allowed through a flap slot exposed by the open lower door and open upper door to enhance stabilized flow on the upper surface aft of the flap slot
Data Source
AI summary
A wing stall compensation mechanism employs an upper door having forward upper hinge end pivotally coupled to an upper wing structure for rotation about an upper axis and a free aft upper end. A lower door has a free aft lower end and a forward lower hinge end pivotally coupled to a lower wing structure for rotation about a lower axis and a 2-bar coupler linkage is disposed between and pivotally coupled to the upper door and lower door. Downward rotation of the upper door in response to wing surface airflow separation causes contraction of the coupler linkage inducing upward rotation of the lower door from a closed position that inhibits airflow through a flap slot to an open position that enables airflow through the flap slot, to thereby restore wing surface airflow effectiveness.