Variable Ratio Bellcrank for Rotary Wing Flight Control Gain Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional manual flight control systems in hybrid helicopters lack effective means to adjust gain proportionally to piloting parameters, leading to increased risk of exceeding structural and flying limits, particularly at high air speeds, due to the absence of tactile feedback and inadequate sensitivity adjustment mechanisms.
Innovation Solution
A novel bellcrank mechanism that mechanically adjusts the gain of manual flight controls by varying the length of radii connected to a flight-attitude-changing linkage, allowing for proportional adaptation of the gain based on instantaneous flight conditions, thereby reducing pilot authority and enhancing safety and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If power assistance is provided to manual flight controls, then ease of operation is improved, but tactile feedback is lost making it difficult to sense forces on airfoils
Solution Approach 1:
The patent implements a feedback mechanism where the bellcrank mechanism provides mechanical resistance to the pilot's inputs, allowing tactile feedback about airfoil forces to be maintained even with power assistance. The variable ratio mechanism creates a force relationship that gives the pilot information about aerodynamic loads through the control forces required.
2Productivity
If gain of manual flight control is increased, then responsiveness to pilot input is improved, but risk of exceeding structural and flying limits increases at high air speeds
Solution Approach 1:
The patent applies a dynamic gain adjustment mechanism where the bellcrank's variable ratio changes the effectiveness of pilot inputs based on flight conditions. At high air speeds, the mechanism automatically reduces gain to prevent exceeding structural limits, while maintaining high responsiveness at lower speeds where full authority is safe.
Solution Approach 2:
The patent changes the mechanical parameter of the bellcrank ratio dynamically. By varying the ratio between input and output strokes of the bellcrank, the system adjusts the gain of the flight control linkage to match safe operating parameters for current flight conditions, particularly air speed.
3Adaptability or versatility
If variable ratio mechanism is added to bellcrank, then adaptability to different flight conditions is improved, but device complexity increases
Solution Approach 1:
The patent makes the bellcrank mechanism dynamic by allowing its ratio to vary rather than being fixed. This is achieved through a variable ratio mechanism that adjusts the bellcrank geometry or configuration based on flight conditions, providing adaptability while maintaining a relatively simple mechanical implementation.
Data Source
AI summary
The present invention relates to a bellcrank (40) for a flight-attitude-changing linkage (27, 25A, 28A) of the variable gain type. The linkage (27, 25A, 28A) connects a manual flight control device of a rotary wing aircraft (1), e.g. a hybrid helicopter, to at least one airfoil of said aircraft (1) suitable for causing a change in flight attitude. Said bellcrank (40) includes first and second sliders (50, 52). Said first slider (50) is connected to a movable portion (57, 61) of a setpoint flight-attitude-changing linkage (24) that delivers a setpoint, with movements of said linkage causing the gain of said variable-gain linkage (27, 25A, 28A) to be adjusted, which gain is proportional to the position of said movable portion (57, 61).