Advanced emergency collective actuator with friction pull-off and method for a helicopter
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Solution Overview
Problem
Existing emergency collective actuators in helicopters are heavy and large, and sudden power failures can lead to rotor stalling, resulting in catastrophic crashes due to the inability to timely reduce collective pitch.
Innovation Solution
An emergency collective actuator with a motor-driven actuator linkage that disengages the friction control lever and automatically lowers the collective pitch, reducing the actuation force needed and allowing for a smaller, lighter design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an emergency collective actuator is designed to automatically lower collective pitch during power failure, then flight safety is improved, but the weight and size of the actuator increases
Solution Approach 1:
The friction control lever is designed to transition between engaged and disengaged states dynamically. During normal operation, the friction lever remains engaged to prevent inadvertent collective movement. During emergency power failure, the actuator automatically disengages the friction lever and actuates the collective pitch control, enabling the system to adapt its behavior based on operational conditions while maintaining safety.
Solution Approach 2:
The actuator system incorporates automatic detection of power failure conditions and self-actuates to lower the collective pitch without requiring pilot input. The control system monitors power availability and autonomously activates the actuator when power failure is detected, allowing the system to service itself in emergency conditions.
2Weight of moving object
If the actuator design is made compact and lightweight, then weight and size are reduced, but the actuation force required increases
Solution Approach 1:
The friction control lever serves as an intermediary mechanism between the actuator and the collective pitch control system. By disengaging the friction lever first, the actuator reduces the static friction force that would otherwise resist collective movement. This intermediary action reduces the peak actuation force required from the motor, enabling a more compact and lightweight actuator design.
Solution Approach 2:
The actuator performs a preliminary action by disengaging the friction control lever before actuating the collective pitch control. This preliminary disengagement reduces the resistance force that the motor must overcome during subsequent collective pitch adjustment, allowing for a smaller, lighter motor design while maintaining sufficient actuation capability.
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 actuator reduces the risk of rotor stalling by automatically adjusting collective pitch during power failures, minimizing weight and size while maintaining flight safety.
Implementation Method 1
an actuator including a motor having an output shaft for rotation to change the adjustable pitch by exerting an actuation force
Implementation Method 2
a friction control lever as part of a friction control that is engageable by the pilot to selectively increase a control force that is required as a minimum to move the collective control
Data Source
AI summary
An emergency collective actuator includes an actuator motor to produce an actuation force and an actuator linkage that directly engages a friction control lever that is pivotally supported on the collective stick of a helicopter to apply the actuation force directly to the friction control lever such that the actuation force initially disengages the friction control and then reduces the adjustable pitch toward a minimum collective pitch position. The actuator can include a clutch that slips to allow the pilot to overcome the actuation force and that slips responsive to an engagement of the friction control by the pilot, but otherwise the clutch co-rotates with the motor shaft to bias the adjustable pitch toward a minimum collective pitch position.