Bistable Pitch Propeller Blade Positioning via Aerodynamic Forces
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Solution Overview
Problem
Existing rotor and propeller systems require complex mechanical mechanisms to vary blade pitch for efficient hovering and forward flight, which increase weight and cost.
Innovation Solution
A bistable pitch propeller system that uses aerodynamic forces and mechanical stops to rotate blades into two stable positions, optimizing angle of attack for hovering and forward flight without the need for complex mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex mechanical mechanisms are used to vary blade pitch, then the propeller can switch between different angles of attack for hovering and forward flight, but the weight and cost increase
Solution Approach 1:
The patent extracts and eliminates the complex mechanical pitch variation mechanisms from the propeller system. Instead of using mechanical linkages, actuators, and control systems, the invention uses fixed-pitch propellers that rely on aerodynamic forces and centrifugal effects to achieve pitch changes, thereby removing unnecessary mechanical components and reducing weight
Solution Approach 2:
The propeller system performs pitch adaptation automatically through aerodynamic self-regulation. The blades self-adjust their effective pitch angle based on rotational speed and angle of attack conditions without requiring external mechanical control systems, allowing the system to serve itself in adapting to different flight modes
2Adaptability or versatility
If complex mechanical mechanisms are used to vary blade pitch, then the propeller can switch between different angles of attack for hovering and forward flight, but the cost increases
Solution Approach 1:
The patent removes expensive mechanical pitch control mechanisms including actuators, linkages, and control systems from the propeller design. By using simple fixed-pitch blades that rely on aerodynamic principles for pitch adaptation, the manufacturing cost is significantly reduced while maintaining the ability to switch between hovering and forward flight modes
Solution Approach 2:
The invention employs simple, inexpensive blade designs that can be manufactured using basic processes. The propeller system uses readily available materials and straightforward construction methods, replacing complex expensive mechanical components with simpler, more cost-effective aerodynamic solutions
3Weight of moving object
If aerodynamic forces and mechanical stops are used to rotate blades into stable positions, then weight and cost are reduced, but the system must ensure blades are always in a known position to maintain stability
Solution Approach 1:
The patent replaces complex mechanical position control systems with aerodynamic stabilization mechanisms. Mechanical stops and aerodynamic forces work together to automatically position blades in stable equilibrium positions corresponding to different flight modes, eliminating the need for sensors, actuators, and control systems while ensuring reliable blade positioning
Solution Approach 2:
The system changes aerodynamic parameters such as rotational speed and angle of attack to transition between stable blade positions. By varying these parameters, the propeller automatically shifts between hovering-optimized and forward-flight-optimized blade configurations, ensuring blades are always in a known stable position appropriate for the current flight condition
4Ease of manufacture
If aerodynamic forces and mechanical stops are used to rotate blades into stable positions, then cost is reduced, but the system must ensure blades are always in a known position to maintain stability
Solution Approach 1:
The patent replaces expensive mechanical position control systems with simple aerodynamic stabilization mechanisms. Mechanical stops combined with aerodynamic forces provide automatic blade positioning without requiring sensors, actuators, or complex control systems, reducing cost while ensuring reliable blade positioning through passive aerodynamic stability
Solution Approach 2:
The propeller system self-regulates blade position through aerodynamic forces that automatically stabilize blades in appropriate positions for different flight modes. The system uses its own operational parameters (rotational speed, airflow) to maintain blade stability without external control, ensuring reliability while minimizing cost
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 allows for efficient transition between hovering and forward flight modes with reduced weight and cost, maintaining stability and performance by ensuring blades are always in a known position, minimizing vibration and improving flight efficiency.
Implementation Method 1
Rotation of the propeller at the first rotational speed causes the blade to rotate (if/as necessary) about the longitudinal axis to a first stable position
Implementation Method 2
a portion of the blade and/or a structure coupled mechanically to the blade engages a mechanical stop, resulting in the blade presenting a first angle of attack
Data Source
AI summary
A propeller includes a blade free to rotate about a longitudinal axis of the blade. The propeller also includes a mechanical stop positioned to engage mechanically a first portion of the blade and/or a first structure coupled mechanically to the blade when the blade is in a first position. The propeller also includes a magnetic stop positioned to engage magnetically a second portion of the blade and/or a second structure coupled mechanically to the blade when the blade is in a second position. The blade rotates to the first position against the mechanical stop when the propeller is rotated at a first rotational speed and the blade rotates to the second position against the magnetic stop when the propeller is rotated at a second rotational speed in a same direction as when the blade is in the first position.