Over-center Gimbal Actuation Lock for VTOL Propulsion
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Solution Overview
Problem
Conventional VTOL aircraft lack a passive gimbal lock mechanism that can efficiently transition between vertical takeoff and landing modes and high-speed forward flight, resulting in increased drag and reduced speed capabilities.
Innovation Solution
A propulsion assembly with an over-center locking mechanism that engages and disengages a gimbal lock using a spring-loaded linkage and rotating actuator, allowing for passive locking and efficient rotor blade folding, enabling high-speed forward flight by reducing drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gimbal lock device is used, then the hub can be locked to prevent flapping, but the device does not provide passive locking and requires continuous energy to maintain the locked position
Solution Approach 1:
The over-center linkage mechanism automatically maintains the locked position through its own geometric configuration and spring force, without requiring external energy input. The mechanism serves itself by using the spring-loaded linkage to hold the gimbal lock in place once engaged, eliminating the need for continuous power supply
Solution Approach 2:
The spring-loaded linkage provides periodic resetting force to maintain the over-center position. The spring periodically re-energizes the linkage to ensure it remains locked, creating a self-sustaining periodic action that maintains the locked state without continuous external energy input
2Speed
If the rotor blades remain extended during forward flight, then the aircraft can maintain lift, but drag increases significantly reducing speed capabilities
Solution Approach 1:
The rotor blade configuration is made dynamic by enabling folding capability. The blades can transition between extended and folded positions based on flight mode requirements. During high-speed forward flight, the blades fold to minimize drag, while during vertical flight they extend to provide lift, creating an adaptive dynamic system
Solution Approach 2:
The physical configuration parameter of the rotor blades changes from extended to folded position. This parameter change allows the aircraft to optimize performance for different flight regimes - extended for lift generation and folded for drag reduction during high-speed forward flight
3Use of energy by moving object
If a passive over-center locking mechanism is implemented, then energy consumption is reduced, but the device complexity increases due to additional linkage components
Solution Approach 1:
The over-center linkage mechanism performs multiple functions: it provides the locking action, maintains the locked position passively, and can be integrated with existing actuator systems. The spring-loaded linkage serves both as a locking mechanism and as a position-maintaining element, reducing the need for separate components
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 higher speed capabilities during forward flight by minimizing drag through rotor blade folding and provides a reliable, non-energized locking system for efficient mode transitions.
Implementation Method 1
a spring-loaded link that is coupled between the pivot idler and the gimbal lock
Implementation Method 2
The pivot idler is held in the locked over-center position by the spring-loaded link
Implementation Method 3
The pivot idler may be held in the open position by a centrifugal force, which is generated by rotation of the mast
Data Source
AI summary
Embodiments are directed to a propulsion assembly for an aircraft. The propulsion assembly comprises a mast, a hub assembly coupled to the mast and having a gimballing degree of freedom relative to the mast, the hub assembly having an inner hub wall spaced part from the mast, a gimbal lock positioned about the mast, the gimbal lock configured to fit between the inner hub wall and the mast in an engaged position, and an over-center locking mechanism coupled to the gimbal lock. The gimbal lock is movable between a disengaged position and the engaged position relative to the hub assembly. The gimbal lock enables the gimballing degree of freedom in the disengaged position and disables the gimballing degree of freedom in the engaged position. The over-center locking mechanism is configured to move the gimbal lock between the engaged position and the disengaged position.