Bistable Pitch Propeller Blade Aerodynamic Positioning
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Solution Overview
Problem
Existing rotor and propeller systems require complex and costly mechanical mechanisms to switch between angles of attack for hovering and forward flight, increasing weight and expense.
Innovation Solution
A bistable pitch propeller system that uses aerodynamic forces to rotate blades into two stable positions, one optimized for hovering and the other for forward flight, without the need for electro-mechanical structures, utilizing mechanical stops and bearings to maintain blade positions during rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex mechanical mechanisms are used to vary propeller pitch between hovering and forward flight angles, then the propeller can switch between different angles of attack, but the system weight and cost increase
Solution Approach 1:
The patent removes complex electro-mechanical pitch control mechanisms from the propeller system, extracting only the essential mechanical elements (blade, hub, bearing, stop) needed for bistable operation. This eliminates unnecessary weight while retaining the ability to switch between hovering and forward flight angles through aerodynamic forces alone
Solution Approach 2:
The propeller blade automatically adjusts its pitch angle based on rotation direction using aerodynamic forces and mechanical stops, without requiring external actuators or complex control systems. The system serves itself by utilizing the rotation direction and aerodynamic loading to automatically position the blade at the appropriate pitch angle for either hovering or forward flight
2Adaptability or versatility
If complex electro-mechanical structures are used to vary propeller pitch, then the propeller can switch between different angles of attack, but the system cost increases
Solution Approach 1:
The patent extracts and removes expensive electro-mechanical pitch control components, retaining only simple mechanical elements (blade, hub, bearing, stop) that can be manufactured at low cost. This dramatically reduces manufacturing complexity and expense while maintaining the essential bistable pitch functionality
Solution Approach 2:
The patent employs simple, inexpensive mechanical components rather than expensive electro-mechanical systems. The design uses basic elements like a simple bearing and stop that are much cheaper to manufacture and replace compared to complex pitch control mechanisms, making the overall system more cost-effective
3Weight of moving object
If aerodynamic forces are used to rotate blades into stable positions without electro-mechanical structures, then weight and cost are reduced, but the mechanism for maintaining blade positions must be simplified
Solution Approach 1:
The aerodynamic forces generated during propeller rotation automatically position and hold the blade at the appropriate pitch angle for the given rotation direction. The system uses the rotation itself to activate the pitch change, with aerodynamic loading pushing the blade against the mechanical stop to maintain the stable position, eliminating the need for external actuators or complex control mechanisms
Solution Approach 2:
The patent changes the operational parameter from active electro-mechanical control to passive aerodynamic positioning. By utilizing the aerodynamic forces generated during rotation and the bidirectional rotation capability, the system automatically transitions between pitch angles based on rotation direction, simplifying the mechanical mechanism while maintaining effective pitch control
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
Enables efficient switching between hovering and forward flight modes with reduced weight and cost, as the propeller blades automatically adjust their pitch based on rotation direction, optimizing performance for different flight conditions.
Implementation Method 1
aerodynamic forces act on the propeller blade to rotate the blade about a longitudinal axis of the blade
Data Source
AI summary
A propeller includes a blade free to rotate. A first stop is positioned to mechanically engage one or both of a first portion of the blade and a first structure coupled to the blade when the blade is in a first position at a first end of the rotational range of motion. A second stop is positioned to mechanically engage one or both of a second portion of the blade and a second structure coupled to the blade when the blade is in a second position at a second end of the defined rotational range. The blade rotates to the first position against the first stop when the propeller is rotated in a first direction and to the second position against the second stop when the propeller is rotated in a second direction.