Compact Fowler Flap Linkage for Reduced Cruise Drag
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Solution Overview
Problem
Current aircraft flap mechanisms with large Fowler motion and trailing edge variable camber require deep and wide aerodynamic fairings, leading to excessive cruise drag due to the need for a larger support structure and fairing to accommodate increased wing chord length and flap support, which complicates achieving both efficient take-off and landing positions and aerodynamically sealable cruise positions.
Innovation Solution
A compact trailing edge flap linkage system with a support beam and flap carrier beam, featuring multiple rotation axes and interconnected links, along with an actuation system that includes a rotary or linear actuator, allows for large Fowler extension and droop motion while maintaining a compact profile, utilizing a hinged quadrilateral linkage and spherical bearings for flexibility and torsional rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a simple hinged flap is used with increased Fowler motion, then the flap can provide larger wing chord length extension, but the hinge axis must be offset greater distance below the wing requiring larger fairing which increases cruise drag
Solution Approach 1:
The flap mechanism is divided into multiple segments: a support beam with first and second portions, a flap carrier beam, and multiple links (first link, second link, connection link) connecting them through rotation axes. This segmentation allows each component to perform a specific function, achieving large Fowler motion while keeping the overall fairing compact to reduce cruise drag.
Solution Approach 2:
The mechanism transitions from a simple single-axis hinge to a multi-dimensional linkage system with rotation axes arranged in specific spatial configurations. The first and second rotation axes of the support beam, combined with the first, second, and third rotation axes of the flap carrier beam, create a three-dimensional motion space that enables large Fowler extension without requiring proportional increases in fairing size.
2Adaptability or versatility
If the hinge axis is offset greater distance below the wing to accommodate larger flap support structure, then larger flaps and increased Fowler motion are achieved, but the fairing size increases which increases airplane aerodynamic drag
Solution Approach 1:
The linkage components are nested within each other in a compact arrangement. The first link connects the support beam to the flap carrier beam, the second link connects the flap carrier beam to the support beam, and the connection link integrates the ground connection. This nested configuration allows the mechanism to accommodate large flap support capabilities while maintaining a compact fairing profile that minimizes aerodynamic drag.
3Object-generated harmful factors
If a compact linkage system is used to reduce fairing size and cruise drag, then aerodynamic efficiency is improved, but the mechanism complexity increases with multiple rotation axes and links
Solution Approach 1:
The linkage system is designed to perform multiple functions simultaneously: the support beam provides structural support and enables Fowler motion; the flap carrier beam supports the aerodynamic flap and transmits motion; the first and second links coordinate the rotation axes for controlled flap movement; the connection link provides ground connection and stabilizes the mechanism. This multi-functionality achieves compact fairing size and reduced cruise drag while managing the inherent complexity through integrated design.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A trailing edge flap mechanism incorporates a hinged quadrilateral linkage for large Fowler extension, trailing edge viable camber and droop motion. The linkage includes a support beam (14) having a first portion (16) with a first rotation point (18) and a fourth rotation point (20) aft of the first rotation point. A flap carrier beam (22) supports an aerodynamic flap (12) and has a second rotation point (24) at a forward end and a third rotation point (26) within a nose contour (28) of the flap aft of the second rotation point. A first link (30) interconnects the first rotation point (18) and second rotation point (24) and a second link (32) interconnects the third rotation point (26) and fourth rotation point (20). The support beam (14) further has a second portion (34) extending angularly forward from the first portion and with a fifth rotation point (36) at a forward end for ground connection on a first fixed axis of rotation. A connection link (40) has a sixth rotation point (42) at a forward end for ground connection on a second fixed axis of rotation and a seventh rotation point (46) connected to the first link (30) intermediate the first (18) and second (24) rotation points. An actuator (48) is connected with a drive link (50) pivotally engaged to the first link (30). Actuation by the drive link provides initial forward and aft movement of a nose profile of the Fowler flap substantially parallel to the wing lower surface with extending aft movement providing a rapidly changing angle of the flap with respect to the wing upper surface.