Rotor Feathering Drain Control for Stable Propeller Pitch Transition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional propeller feathering systems in aircraft can cause sudden changes in forces and controllability issues due to abrupt transitions from high thrust to zero thrust, leading to potential hazardous flight safety events, and there is a need for improved control methods to manage these transitions.
Innovation Solution
A rotor control system with a feathering system that includes a main control valve, a feather valve, and a feather drain control valve, which allows for gradual reduction of drainage flow during the feathering mode, enabling controlled transition from high thrust to zero thrust, reducing the risk of overcorrection and maintaining aircraft stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If maximum drainage flow is used during feathering mode, then the propeller transitions quickly to feather position, but sudden changes in thrust and rolling forces occur affecting aircraft controllability
Solution Approach 1:
The system dynamically adjusts the drainage flow rate during feathering operation. The feather drain control valve transitions from a fully open state (allowing maximum drainage) to a progressively restricted state, modulating the flow rate based on aircraft rolling momentum conditions. This dynamic adjustment resolves the contradiction by enabling fast initial feathering when safe, then slowing down to maintain controllability.
Solution Approach 2:
The system changes the flow rate parameter of hydraulic drainage during feathering. By controlling the feather drain control valve to restrict drainage flow rate progressively, the system transforms the constant maximum flow rate into a variable flow rate that adapts to aircraft stability requirements, resolving the contradiction between speed and controllability.
2Loss of time
If maximum drainage flow is used during feathering mode, then the propeller feathers quickly, but significant loads are imposed on engine and aircraft structures
Solution Approach 1:
The system applies dynamic control to the drainage flow, starting with maximum flow for rapid initial feathering when structural loads are manageable, then progressively restricting flow as the propeller approaches feather position. This dynamic approach minimizes total feathering time while preventing excessive structural loads during the transition.
Solution Approach 2:
The system prepares for potential structural overload by implementing progressive flow restriction before maximum feathering is achieved. The feather drain control valve anticipates the increasing loads that would occur with sustained maximum drainage and preemptively reduces flow rate to cushion against excessive structural stress.
3Productivity
If maximum drainage flow is used during feathering mode, then the propeller reaches feather position quickly, but overcorrection may occur after unsafe state is prevented
Solution Approach 1:
The system uses feedback from aircraft rolling momentum sensors to control the feather drain control valve. When rolling momentum exceeds thresholds, the system restricts drainage flow rate, creating a feedback loop that prevents overcorrection. This resolves the contradiction by maintaining fast response while ensuring precision through continuous monitoring and adjustment.
Solution Approach 2:
The system dynamically adjusts drainage flow rate based on real-time aircraft state feedback. The feather drain control valve transitions from static maximum opening to dynamic positioning, adjusting flow rate in response to rolling momentum conditions. This dynamic feedback control achieves both rapid response and precise control without overcorrection.
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 effectively manages propeller blade angle transitions by gradually reducing drainage, preventing overcorrection and maintaining aircraft stability, thus enhancing flight safety by avoiding sudden changes in thrust and rolling forces.
Implementation Method 1
A feather drain control valve can be included in the drain conduit or second line either upstream or downstream of the feather valve and feather solenoid for control of flow in the drain conduit during the feathering mode
Implementation Method 2
A feather solenoid can be operatively connected to control a piston of the feather valve for actuating the feather valve between connecting the second conduit in fluid communication with either the first conduit or with the drain conduit
Data Source
AI summary
The rotor control system includes a main control valve having an inlet for receiving liquid and an outlet for issuing liquid to a rotor pitch change actuator. The rotor control unit is configured to control flow of liquid from the inlet to the outlet to modify pitch angle of rotor blades. A feathering system with a first conduit connected in fluid communication with the outlet of the main control valve, a second conduit for fluid communication with the rotor pitch change actuator, and a drain conduit. The feathering system has a normal operation mode for supplying liquid from the main control valve to the rotor pitch change actuator by allowing flow through the feathering system from the first conduit to the second conduit. The feathering system has a feathering mode for controlling drainage from the rotor pitch change actuator to the drain conduit.