Coaxial Rotor Assembly With Variable Blade Phasing for VTOL Cruise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft rotor assemblies face challenges in minimizing aerodynamic drag, vibration, and acoustic noise during various flight modes, particularly when configured for both vertical takeoff and landing (VTOL) and cruising flight, while maintaining the number of rotor blades for optimal thrust.
Innovation Solution
The rotor assembly features coaxial rotors with blades separated by 180 degrees and an adjustable differential phase angle, allowing synchronous operation for takeoff and landing, and alignment with air flow for cruising to reduce drag, and a drive assembly to control the phase angle for noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If rotor blades are kept in a deployed position for optimal thrust during VTOL operation, then lift generation is improved, but aerodynamic drag increases during cruising flight
Solution Approach 1:
The rotor blades are configured to be dynamically adjustable between a deployed position for VTOL operations and a retracted position for cruising flight. The system transitions from static blade configuration to dynamic adjustment, allowing optimal performance in both flight modes without continuously incurring drag penalties.
Solution Approach 2:
The invention changes the spatial parameter of blade orientation by 180 degrees between operating modes. During VTOL, blades are positioned at an optimal angle for maximum lift; during cruising, blades are rotated to a retracted position that minimizes aerodynamic interference and drag, thus changing the operational parameters to match flight requirements.
2Force
If multiple rotor assemblies are operated simultaneously for sufficient thrust, then vertical lift capability is improved, but vibration and acoustic noise increase
Solution Approach 1:
The invention introduces asymmetric phasing between the first and second rotor assemblies, with rotors offset by 180 degrees in their rotational cycles. This asymmetric configuration causes the vibration and acoustic signatures of the two rotors to be out of phase, leading to destructive interference that reduces overall vibration and noise levels while maintaining sufficient vertical lift capability.
3Force
If rotor blades are positioned for optimal thrust during takeoff and landing, then lifting force is improved, but acoustic emission increases during these operations
Solution Approach 1:
The asymmetric 180-degree phasing between rotor assemblies creates opposing acoustic waves that interfere destructively, reducing the overall acoustic emission during VTOL operations. This allows the system to maintain optimal blade positioning for lifting force while simultaneously reducing the harmful acoustic signature through the asymmetric configuration.
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 configuration enhances thrust during takeoff and landing while minimizing drag and noise during cruising, providing efficient and quiet operation across different flight modes.
Implementation Method 1
Aircraft rotor assemblies face challenges in minimizing aerodynamic drag, vibration, and acoustic noise during various flight modes, particularly when configured for both vertical takeoff and landing (VTOL) and cruising flight
Implementation Method 2
alignment with air flow for cruising to reduce drag
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An aircraft rotor assembly (12) comprises first and second rotors (42A, 42B) and a drive assembly (46). The first and second rotors are rotatable about a common axis (A) synchronously and with respect to each other. The first rotor has a first blade (44A) extending radially from the common axis; the second rotor has a second blade (44B) extending radially from the common axis, longitudinally offset from the first blade along the common axis. The drive assembly is coupled to the first and second rotors and configured to controllably vary, during continuous rotation of the first and second rotors, a differential phase angle (φ) separating the first and second blades as projected onto a plane (PA, PB) perpendicular to the common axis.