Underwing Bifold Flaps With Internal Linkage for Lower Drag
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Solution Overview
Problem
Aircraft wings with trailing edge flaps suffer from significant parasitic drag due to fairings covering linkage assemblies, which negatively impact aerodynamic performance, particularly during cruise operations.
Innovation Solution
The implementation of underwing-mounted trailing edge bifold flaps with a foldable design that stows the linkage assembly within the wing compartment, eliminating the need for fairings and reducing drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trailing edge flap is implemented using a Fowler flap design with guide tracks and linkage assembly, then the flap can be extended rearward to increase wing camber and lift, but a fairing must cover the linkage assembly which produces significant parasitic drag that negatively impacts aerodynamic performance during cruise operations
Solution Approach 1:
The invention extracts the linkage assembly from the external environment by stowing it within an internal compartment of the wing. The flap is connected to the linkage assembly through a opening in the wing, allowing the linkage to remain hidden inside the wing structure rather than requiring external fairings, thereby eliminating the parasitic drag problem associated with traditional Fowler flap linkages.
Solution Approach 2:
The linkage assembly is nested within the internal compartment of the wing structure. The flap panel is positioned such that when viewed from below, it is substantially coplanar with the lower surface of the wing, creating a streamlined appearance without external fairings. The linkage assembly fits within the wing's internal volume, utilizing the existing structural space efficiently.
2Object-generated harmful factors
If the linkage assembly is stowed within an internal compartment of the wing, then parasitic drag is reduced and aerodynamic performance is improved, but the linkage assembly requires a more complex internal structure and opening mechanism
Solution Approach 1:
The internal compartment serves multiple functions: it houses the linkage assembly, provides structural support for the flap mechanism, and maintains the aerodynamic contour of the wing. The opening in the lower surface serves dual purposes as both an access point for the linkage and an aerodynamic feature when closed.
Solution Approach 2:
Instead of placing the linkage assembly externally and covering it with a fairing (traditional approach), the invention inverts the approach by placing the linkage internally and using the wing structure itself as the covering, eliminating the need for separate fairings and reducing overall structural complexity.
3Reliability
If the flap is designed to increase wing camber and effective area for safer landings on short runways, then takeoff and landing performance is improved, but the flap structure and its movement mechanism become more complex
Solution Approach 1:
The flap is segmented into a forward panel and an aft panel that can fold relative to each other. This bifold configuration allows the flap to achieve greater camber and effective area changes while maintaining a more compact stowed position. The segmentation enables the flap to provide enhanced lift for short runway operations without requiring an excessively large or complex external structure.
Data Source
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AI summary
Underwing-mounted trailing edge bifold flaps for wings of aircraft are disclosed. A bifold flap pivotally coupled to the wing is movable between a stowed position located along a lower surface of the wing and a deployed position located rearward of a trailing edge of the wing. The bifold flap includes a forward panel and an aft panel. The aft panel is pivotally coupled to the forward panel and foldable relative thereto. The aft panel is folded toward the forward panel when the bifold flap is in the stowed position. The aft panel is unfolded from the forward panel when the bifold flap is in the deployed position. A bullnose pivotally coupled to the forward panel pivots relative to the bifold flap as the bifold flap moves between the stowed and deployed positions.