Variable Geometry Rotor Blade With Solid Flexure Joint
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Solution Overview
Problem
Existing rotor blades for helicopters face challenges in adapting to varying flight conditions due to conflicting demands on geometry under centrifugal forces, which hinder efficient operation during hovering, take-off, landing, and forward flight.
Innovation Solution
A rotor blade design featuring a solid flexure joint and pneumatic actuator that allows deformation perpendicular to the main plane, enabling configuration adjustments without parts sliding or rolling, and utilizing a locking mechanism to maintain deformations, allowing for optimal geometry adaptation across flight states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional rotor blade geometry is used, then the blade is stable under centrifugal forces, but it cannot adapt to different flight conditions (hovering vs forward flight)
Solution Approach 1:
The rotor blade transitions from a static geometry to a dynamic, variable geometry system. The blade can change its shape (sweep angle, twist angle, span) using actuators (pneumatic or hydraulic) that modify the position of blade sections relative to each other, allowing adaptation to different flight conditions while maintaining reliability through controlled actuation mechanisms
Solution Approach 2:
The rotor blade is divided into multiple separable sections (root section, intermediate sections, tip section) that can move relative to each other. This segmentation allows independent control of different blade portions, enabling geometric adaptation while each section maintains structural integrity under centrifugal forces
2Adaptability or versatility
If variable geometry mechanisms are added to adapt to different flight conditions, then adaptability improves, but device complexity increases
Solution Approach 1:
Traditional mechanical linkage systems are replaced with pneumatic or hydraulic actuators that use fluid pressure to control blade geometry changes. This substitution reduces mechanical complexity by eliminating complex gears, linkages, and mechanical joints while providing smooth, continuous geometric adjustment capability
Solution Approach 2:
The blade incorporates flexible elements (flexible spars, flexible trailing edges) that can deform under pneumatic/hydraulic pressure to achieve geometric changes. These flexible elements provide continuous adaptability without requiring multiple discrete mechanical components
3Adaptability or versatility
If pneumatic actuators are used for deformation, then adaptability improves, but parts sliding or rolling under centrifugal forces causes malfunctions
Solution Approach 1:
The invention extracts and eliminates sliding or rolling contact surfaces from the actuator system. Pneumatic actuators use sealed chambers with flexible diaphragms or bellows that expand/contract without any sliding parts, preventing centrifugal forces from causing wear, binding, or malfunction of moving components
4Productivity
If blade geometry is optimized for forward flight, then flow resistance decreases, but performance during hovering and take-off deteriorates
Solution Approach 1:
The rotor blade uses dynamic geometry adjustment to optimize performance for different flight phases. During forward flight, the blade adopts a geometry with reduced sweep and twist for lower drag and higher speed. During hovering and take-off, the blade transitions to a geometry with increased sweep and twist for enhanced lift generation, with the actuator system enabling real-time reconfiguration
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 design effectively adapts rotor blade geometry to different flight conditions without unwanted deformations or malfunctions due to centrifugal forces, optimizing lift and reducing flow resistance for high-speed forward flight.
Implementation Method 1
hose actuators...which expand in diameter when their interior is acted upon by a hydraulic medium and thus shorten between their connection points
Implementation Method 2
an interface is known from DE 10 2010 029 088 A1, which has two connection areas connected to one another by a joint, the joint being embedded in a large number of particles which are pressed against one another, for example by an elastic covering, in such a way that they block the joint . This blockage can be temporarily lifted, for example, by applying pneumatic pressure to the cover from the inside.
Implementation Method 3
the joint being embedded in a large number of particles which are pressed against one another, for example by an elastic covering
Implementation Method 4
the hovering flight of the helicopter, in which the horizontal rotor has to generate the required lift solely through rotation
Implementation Method 5
the horizontal rotor has to generate the required lift solely through rotation
Implementation Method 6
the forward flight of the helicopter, in which an inflow of the rotor blades of the horizontal rotor also occurs due to its relative movement compared to the ambient air takes place
Data Source
Figure 1~2
Figure 3
AI summary
In a rotor blade (1) having at least one joint and at least one actuator to cause deformation of the rotor blade (1) about the joint, the joint is a solid joint (8) and the actuator is a pneumatic actuator.