Lower Wing Spoiler for Aft-Loaded Aircraft Wing Load Alleviation
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Solution Overview
Problem
Aircraft wings, particularly those designed for transonic speeds, face challenges in managing load alleviation during extreme flight conditions such as maneuvers and turbulence, as existing solutions primarily focus on upper surface modifications, neglecting the rear wing section which contributes significantly to lift and bending moments.
Innovation Solution
A spoiler or similar device is integrated into the lower surface of the wing, specifically in the aft-loaded section, to reduce lift by causing flow separation, which can be hinged, deformable, or porous, and is often used in conjunction with upper surface spoilers to manage load distribution and reduce structural stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If spoilers are deployed on the upper surface to reduce lift, then wing root bending moment is reduced, but the rear wing section continues to generate significant lift that cannot be effectively controlled
Solution Approach 1:
The patent applies flow separation on the lower surface of the wing instead of the conventional upper surface. By inverting the location of the spoiler from the upper to lower surface, the invention achieves effective lift reduction on the rear wing section where conventional upper surface spoilers are ineffective.
Solution Approach 2:
The invention places flow separation devices specifically on the lower surface of the rear wing section (aft of maximum thickness), creating localized flow separation only where needed. This targeted approach allows independent control of the rear section lift without affecting the forward section.
2Productivity
If the wing is designed as aft-loaded with concave rear section to increase lift, then cruise performance is improved, but wing loads during maneuvers and turbulence increase
Solution Approach 1:
The invention makes the wing's lift characteristics dynamic by using deployable flow separation devices on the lower surface. During cruise, the devices are retracted allowing the aft-loaded configuration to generate maximum lift. During maneuvers or turbulence, the devices are deployed to actively reduce lift and wing loads in real-time.
Solution Approach 2:
The flow separation devices on the lower surface are positioned to counteract the lift-generating concave rear section geometry. When deployed, they create adverse pressure gradients that prevent the rear section from generating excessive lift, thereby preemptively reducing wing loads before they become problematic.
3Force
If spoilers are placed further outboard on the upper surface, then moment reduction at wing root increases, but device complexity and interference with flaps increase
Solution Approach 1:
Instead of placing spoilers on the upper surface where they would interfere with flaps and require complex configurations, the invention inverts the approach by placing flow separation devices on the lower surface. This eliminates interference issues and simplifies the overall device configuration while achieving the same moment reduction effect.
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
This solution effectively reduces wing loads and structural weight by targeting the lift component from the rear wing section, enhancing load alleviation and allowing for a potentially smaller upper surface spoiler and lighter actuator, thereby improving flight stability and reducing drag.
Implementation Method 1
The invention concentrates on fitting the device in the rear part... to reduce the lift component from the rear part of the wing, aft of maximum thickness... causing flow separation
Data Source
Figure 1~3(b)
Figure 4a~6
Figure 7~8
AI summary
Modern aircraft wings generally have a lower surface the rear part of which is concave over at least some of its length, for additional lift. Sometimes it is desirable to reduce the wing lift, for instance during turbulence. To this end the wing 1 has, located at least partly in or forward of this concave part and forward of the trailing edge, a spoiler device such as a deployable spoiler 20 operable to change between a configuration in which the surface is uninterrupted and one in which the device separates flow, so as to reduce local lift over the concave portion. An actuator 26 can be provided for deploying the spoiler, and an upper spoiler 40 can also be present, operated by the same or a separate actuator. Alternatively the spoiler device can include a flexible or deforming material 120 operable to protrude from the wing surface.