VTOL Rotor Assembly Damper System for Drag Reduction
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Solution Overview
Problem
Existing rotor assembly designs for VTOL aircraft face challenges in efficiently transitioning between vertical takeoff and cruise modes due to high complexity, unreliable stowing and deployment mechanisms, high maintenance costs, and excessive drag, which affect fuel economy and range.
Innovation Solution
A rotor assembly with a damper system that allows for relative rotation between two rotors to adopt a stowed configuration for reduced drag and a deployed configuration for thrust generation, using passive forces like drag and inertia to control the transition, reducing the need for active control systems and minimizing complexity and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active control systems (motors and actuators) are used to deploy and stow rotor assemblies, then reliability and controllability improve, but device complexity, weight, and cost increase
Solution Approach 1:
The rotor assembly uses its own operational characteristics (drag and inertia) to automatically deploy and stow itself without external control systems. During cruise flight, aerodynamic drag on the rotors naturally drives them into the stowed configuration, while during VTOL operations, inertial forces from rotor acceleration automatically deploy them, eliminating the need for motors and actuators
Solution Approach 2:
The invention converts previously harmful or wasted forces (aerodynamic drag and inertial effects) into useful functions for automatic rotor deployment and stowing. Forces that were considered parasitic losses in conventional designs become the primary mechanism for configuration transitions, reducing system complexity while maintaining reliability
2Reliability
If rotor assemblies are left in deployed configuration during cruise flight, then thrust generation capability is maintained, but drag increases reducing fuel economy and range
Solution Approach 1:
The rotor assembly transitions from a static fixed configuration to a dynamic reconfigurable system that automatically adapts its configuration based on flight phase. The rotors dynamically shift between deployed and stowed positions in response to changing aerodynamic and inertial conditions, optimizing performance for each flight regime without requiring active control
Solution Approach 2:
The system changes the spatial configuration parameter of the rotor assembly (deployed vs. stowed position) in response to flight condition changes. During cruise, the configuration parameter shifts to stowed to minimize drag, while during VTOL operations, it shifts to deployed to maximize thrust capability, with transitions driven by natural physical forces
3Loss of energy
If complex stowing mechanisms are implemented to reduce drag, then fuel economy improves, but maintenance complexity and cost increase
Solution Approach 1:
The invention extracts and removes the complex motorized stowing mechanisms from the system entirely. Instead of adding specialized deployment systems, it relies on the inherent physical forces (drag and inertia) that already act on the rotor assembly during normal operation, simplifying the system while achieving the same drag reduction benefit
4Speed
If active control systems are used for rotor deployment, then deployment speed improves, but system weight increases
Solution Approach 1:
The rotor assembly performs its own deployment and stowing operations using internally generated inertial forces during acceleration and deceleration, eliminating the need for external motors and actuators that would add weight to the system
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 damper system effectively reduces stress on the rotor assembly, maintains configurations, and improves fuel economy and range by minimizing drag during non-use conditions and optimizing thrust generation during use, while also simplifying the system and reducing failure modes.
Implementation Method 1
the damper system is arranged to generate a damper force opposing the relative rotation between the first and second rotors
Implementation Method 2
passive forces such as drag and/or inertia associated with rotor acceleration or deceleration
Implementation Method 3
passive forces such as drag and/or inertia associated with rotor acceleration or deceleration
Data Source
AI summary
A rotor assembly includes a first rotor, a second rotor and a damper system. The first and second rotors are arranged to be rotated about a common axis for thrust generation by a drive system. The first rotor is rotatable about the common axis relative to the second rotor between a stowed configuration of the rotor assembly in which a rotor blade of the first rotor and a rotor blade of the second rotor are substantially angularly aligned and a deployed configuration in which the rotor blade of the first rotor and the rotor blade of the second rotor are angularly misaligned. The damper system is arranged to generate a damper force opposing the relative rotation between the first and second rotors in at least one of the direction towards the stowed configuration and the direction towards the deployed configuration.