Sigmoidal Wingtip Device Morphing Dihedral Angle
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Solution Overview
Problem
Existing aircraft wingtip devices, such as sharklets, increase mass and induce drag, while proposed variable geometry designs are impractical for commercial aircraft, and there is a need for improved fuel efficiency that balances aerodynamic benefits with mass distribution and structural strength.
Innovation Solution
A wingtip device with a sigmoidal profile, featuring a main aerofoil that varies in dihedral angle from less than +20 degrees to greater than +50 degrees, and a supporting structure that extends beneath the aerofoil, providing structural support and reducing drag, with the ability to morph its shape for different flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a sharklet wingtip device is added to improve aerodynamic performance, then induced drag is reduced, but the mass of the device increases by more than 100 kg
Solution Approach 1:
The patent applies a spiroid (spiral) curved geometry to the wingtip device, replacing conventional planar or simple curved shapes. This spiral configuration reduces induced drag more effectively while distributing mass along the curved path, potentially reducing the concentration of mass at the outboard end compared to traditional sharklets.
Solution Approach 2:
The invention transitions from two-dimensional planar wingtip devices to a three-dimensional spiral configuration. This adds a rotational dimension to the wingtip geometry, allowing the device to interact with airflow in multiple planes and reduce induced drag more efficiently per unit mass.
2Object-generated harmful factors
If a vertical planar region is added at the outboard end of the wingtip device to improve aerodynamic performance, then induced drag is reduced, but the mass distribution shifts outward increasing outboard mass
Solution Approach 1:
The spiral geometry distributes the vertical planar region along a curved path from the wing root outward, rather than concentrating it at the outboard end. This distributes mass more evenly along the span, reducing the penalty of outboard mass while maintaining the drag-reducing vertical surface area.
3Reliability
If structural strength is increased over the whole device to ensure sufficient strength, then reliability is improved, but the total mass of the device increases
Solution Approach 1:
The spiral configuration provides inherent structural efficiency by distributing loads along the curved geometry. The spiral shape naturally resists bending and torsional loads more effectively than straight configurations, allowing for reduced material usage while maintaining structural integrity.
4Use of energy by moving object
If the wingtip device geometry is optimized for take-off conditions, then fuel efficiency during take-off is improved, but performance at cruising altitude is not optimized
Solution Approach 1:
The patent incorporates variable geometry capabilities, allowing the wingtip device to change its configuration between take-off and cruise conditions. This dynamic adjustment enables optimization for low-speed high-lift conditions during take-off while maintaining efficiency at high-speed cruise conditions.
Solution Approach 2:
The invention allows changes in geometric parameters such as dihedral angle, sweep angle, and vertical surface area depending on flight conditions. These parameter changes enable the device to adapt to different Reynolds numbers, speeds, and lift coefficients encountered during various phases of flight.
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 sigmoidal wingtip device reduces induced drag, optimizes fuel efficiency, and distributes mass inboard, maintaining structural integrity while allowing for adjustable aerodynamic performance suited to various flight profiles.
Implementation Method 1
The main aerofoil may have a first portion extending across a significant portion of the total length of the wing tip device... the first portion being shaped such that the angle of the local dihedral varies
Implementation Method 2
Such devices typically improve aerodynamic performance by means of reducing induced drag that would otherwise be caused by vortices downstream of the wingtip of the aircraft wing
Data Source
AI summary
An aircraft wing is disclosed including a closed surface wing tip device which includes an element or actuator within the wing tip for deforming/morphing the shape of the wing tip between geometrical configurations having different aerodynamic properties, for example including one with better overall fuel efficiency for a shorter journey and one with overall fuel efficiency better suited for a longer journey. The device includes a lower winglet with an essentially planar portion spaced apart from the main body of the wing by a blended transition region which is shaped such that the curvature of the local dihedral increases in the outboard direction. The device includes an upper aerofoil structure which with the winglet essentially forms the closed surface. There is also disclosed an aircraft wing tip device having a sigmoid shaped (e.g. S-shaped) aerofoil structure blending in with a main wing of the aircraft.