Variable Twist Wing Control for Drag and Stall Optimization
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Solution Overview
Problem
Existing aircraft wing designs face challenges in minimizing induced drag while maintaining optimal lift, particularly due to limitations in twist distribution optimization and the inability to adapt to varying flight conditions, leading to suboptimal performance during takeoff, landing, and cruising.
Innovation Solution
Implementing a variable-twist control system that continuously optimizes wing twist based on operating conditions using a combination of geometric and aerodynamic twist, allowing for dynamic adjustment of twist distribution and amount to match changing lift coefficients, thereby minimizing induced drag and maximizing lift across the wing span.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a tapered wing is used to reduce induced drag, then induced drag is reduced, but the wing stalls first at the wingtips leading to poor handling characteristics
Solution Approach 1:
The patent applies different twist angles to different sections of the wing span. The root section has a higher angle of attack while the tip section has a lower angle of attack, creating local quality differences that prevent tip stall while maintaining overall lift efficiency. This localized variation in geometric properties resolves the contradiction between drag reduction and stall characteristics.
Solution Approach 2:
The patent employs variable geometry by allowing the wing twist to change dynamically with angle of attack. As the angle of attack increases, the wing automatically adjusts its twist distribution to maintain optimal stall characteristics. This dynamic adaptation allows the wing to reduce induced drag at cruise while preventing tip stall at high angles of attack.
2Loss of energy
If an elliptical wing is used to minimize induced drag, then induced drag is minimized, but the wing stalls uniformly along the span creating dangerous situations
Solution Approach 1:
The patent introduces local quality variations through spanwise twist distribution. While the overall wing may have an elliptical planform for minimum induced drag, the local twist angles vary along the span to create differential stall characteristics. The root section is designed to stall first while tip sections remain attached, providing safe stall recovery characteristics while maintaining the elliptical planform's drag advantages.
3Reliability
If washout is incorporated into a wing to delay stall, then stall characteristics are improved, but lift performance decreases due to reduced angle of attack
Solution Approach 1:
The patent employs dynamic twist adjustment that varies with angle of attack. At low angles of attack during cruise, the wing maintains a configuration that maximizes lift performance. As the angle of attack increases toward stall conditions, the wing automatically increases its twist to delay stall. This dynamic behavior allows the system to achieve both high lift performance and improved stall characteristics without the permanent lift penalty of fixed washout.
Solution Approach 2:
The patent changes the twist parameter dynamically based on flight conditions. Rather than using fixed geometric washout that permanently reduces lift, the system varies the twist parameter in response to angle of attack changes. This parameter change allows the wing to maintain optimal lift at cruise while achieving stall protection at high angles of attack, resolving the contradiction between lift performance and stall characteristics.
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 approach enables aircraft to maintain minimum induced drag and maximum lift throughout the flight envelope, improving fuel efficiency, maneuverability, and safety by dynamically adapting wing twist to changing conditions.
Implementation Method 1
The control system optimizes geometric twist by rotating a portion of the wing about a spanwise axis to achieve a desired twist distribution
Implementation Method 2
The control system optimizes aerodynamic twist by changing the camber of an airfoil section
Implementation Method 3
Lift is the force that is perpendicular to the direction of flight... Lift is generated by every part of the aircraft, but most of the lift on a conventional aircraft is generated by the wings
Implementation Method 4
Induced drag is caused by the generation of lift by a wing and is parallel to the relative wind into which the wing is flying
Data Source
AI summary
A method and apparatus for varying the twist of a wing such that induced drag is minimized or reduced during cruise and lift is maximized or increased at least during takeoff and landings. In addition, variations in the twist may produce yawing and rolling moments. The twist amount is varied pursuant to the operating conditions, including those parameters used to determine the lift coefficient. The twist for reducing induced drag and/or improving lift may be employed by geometric or aerodynamic twist, including full span control surfaces used to provide roll control, high-lift and reduced induced drag. The twist may also be employed by twisting just a portion of the wing or the entire wing, either geometrically or aerodynamically.