Rotor Alignment Tab for AAM Deceleration
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Solution Overview
Problem
Advanced Air Mobility rotor systems face challenges in efficiently stopping and aligning rotor assemblies, particularly due to the complexity and weight of rotor brakes, and the need for mechanical or electronic indexing schemes that increase expense and weight.
Innovation Solution
A passive rotor alignment tab system utilizing centripetal force and aerodynamic loading to actuate a drag or weathervaning force, which aligns the rotor assembly streamwise and retains alignment using a combination of springs and airload, facilitating deceleration and stopping of the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rotor brakes are used to stop the rotor assembly, then the rotor can be effectively decelerated, but the system becomes heavier and occupies more space around the rotor mast
Solution Approach 1:
The patent extracts the braking function from a traditional brake system and implements it through aerodynamic drag generated by the rotor blades themselves. The feathering mechanism allows blades to rotate about their longitudinal axis, presenting a higher drag surface area to the air flow, thereby providing deceleration without mechanical brakes.
Solution Approach 2:
The patent replaces the mechanical brake system with an aerodynamic braking mechanism. Instead of using friction-based mechanical brakes, the system uses air resistance generated by feathering the rotor blades to achieve deceleration, substituting mechanical force with aerodynamic force.
2Stability of the object's composition
If mechanical or electronic indexing schemes are used to maintain rotor alignment, then the rotor can be kept in streamwise alignment, but the system complexity and expense increase
Solution Approach 1:
The patent implements a self-aligning mechanism where the rotor assembly automatically returns to streamwise alignment through aerodynamic forces. When the rotor is stopped or rotating at low speed, the feathering mechanism and blade geometry create aerodynamic moments that naturally guide the rotor back to its proper alignment without requiring external indexing systems.
Solution Approach 2:
The patent replaces mechanical or electronic indexing systems with aerodynamic alignment mechanisms. The rotor alignment is maintained through air flow forces acting on the feathered blades and associated aerodynamic surfaces, substituting complex mechanical/electronic indexing with simpler aerodynamic self-correction.
3Reliability
If rotor brakes and indexing systems are installed, then rotor control is improved, but the available space around the rotor mast is reduced
Solution Approach 1:
The patent merges the braking function and alignment maintenance function into the existing rotor blade structure and aerodynamic system. The feathering mechanism, which is part of the blade assembly, provides both deceleration through drag and alignment through aerodynamic moments, eliminating the need for separate brake and indexing systems that would occupy space around the rotor mast.
Solution Approach 2:
The patent implements multi-functionality in the rotor blade system, where the feathering mechanism serves multiple purposes: it provides aerodynamic braking for deceleration, maintains streamwise alignment through aerodynamic moments, and can potentially control rotor direction. This universal approach eliminates the need for separate dedicated systems for each function.
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 system enables efficient deceleration and streamwise alignment of rotor assemblies, reducing the need for heavy brakes and complex indexing systems, thereby improving weight and cost efficiency while maintaining alignment.
Implementation Method 1
A passive alignment tab mechanism utilizing centripetal force and aerodynamic loading is disclosed
Implementation Method 2
A passive alignment tab mechanism utilizing centripetal force and aerodynamic loading is disclosed
Implementation Method 3
actuate a drag or weathervaning force, which aligns the rotor assembly streamwise
Implementation Method 4
retains alignment using a combination of springs and airload
Implementation Method 5
retains alignment using a combination of springs and airload
Data Source
AI summary
One embodiment is a rotor assembly for an aircraft, the rotor assembly comprising a plurality of rotor blades, wherein at least one of the rotor blades comprises a rotor alignment drag assembly comprising a drag structure on a surface of the at least one of the rotor blades, wherein the drag structure is moveable between a first position in which the drag structure is stowed within the at least one of the rotor blades, and a second position in which the drag structure is extended from the surface of the at least one of the rotor blades; and an actuation mechanism for moving the drag structure from the first position to the second position when a speed of the rotor assembly falls below a first threshold speed.