Rotorcraft Autorotation Control via Variable Force Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current systems for controlling rotorcraft main rotors during autorotation flight phases lack effective means to prevent involuntary desynchronization and power limit exceedance, particularly in low power levels, and do not facilitate safe and stable transition between synchronized and desynchronized states, making pilot workload high and risk of damage possible.
Innovation Solution
A control system with motorized means that allows pilots to manually initiate and control autorotation by positioning a collective pitch control member beyond a first stop position, generating a control setpoint for desynchronization and anchoring in an autorotation position, with sensory feedback to manage rotational speed and prevent power limit exceedance, using a control member with physical stops and motorized actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pilot manually monitors instruments during autorotation, then power limits can be detected, but the pilot cannot perceive overruns on the FLI scale when looking outside during delicate maneuvers
Solution Approach 1:
The patent implements a feedback system where the collective pitch control member provides tactile feedback through variable opposition forces. As the control member approaches positions that would exceed power limits, the motorized means increases the opposing force, giving the pilot direct tactile warning without requiring visual monitoring of instruments. This resolves the contradiction by making power limit detection automatic through force feedback while allowing the pilot to focus on external maneuvers.
2Ease of operation
If the collective pitch control member allows free movement, then the pilot has full control authority, but involuntary desynchronization and power limit exceedance cannot be prevented
Solution Approach 1:
The patent applies preliminary anti-action by using motorized means to generate opposing forces on the collective pitch control member before the pilot can inadvertently cause desynchronization or exceed power limits. The system proactively counteracts potential harmful movements by increasing resistance as the control member approaches critical positions, preventing involuntary desynchronization while preserving full control authority within safe boundaries.
3Loss of information
If the FLI display provides visual information about pitch levels, then power limits can be monitored, but the display does not prevent unexpected desynchronization or help balance the autorotation regime
Solution Approach 1:
The patent introduces the collective pitch control member itself as an intermediary that directly communicates autorotation regime balance to the pilot through tactile feedback. Instead of relying on the FLI display as a separate information channel, the control member becomes a mediator that provides force feedback proportional to how well-balanced the autorotation is, enabling the pilot to feel and correct imbalances without visual attention.
4Reliability
If the motorized means generate strong opposing forces to prevent desynchronization, then autorotation stability improves, but the control member becomes difficult to move manually
Solution Approach 1:
The patent applies dynamics by making the opposing force generated by the motorized means variable rather than constant. The force level adapts dynamically based on the position of the collective pitch control member and the current autorotation regime, providing strong prevention of desynchronization when needed while allowing easy manual movement when the system is in a safe, balanced state. This dynamic adjustment resolves the contradiction between stability and ease of operation.
Data Source
Figure 1~5
AI summary
The present invention relates to a control system (1) for a main rotor (11) of a rotorcraft (10) to achieve an autorotation flight phase of said rotorcraft (10), said control system (1) comprising: • a control element (2) for the collective pitch of the blades (13) of said main rotor (11), said control element (2) being movable over a range of positions between two extreme physical stops, • a calculation unit (3) for calculating a collective blade angle, referred to as the "autorotation collective pitch", of the blades (13) of said main rotor (11), said "autorotation collective pitch" enabling said main rotor (11) to rotate at an optimal rotational speed for said autorotation flight phase of said rotorcraft (10), and • motorized means (4) for positioning said control element (2) in a predetermined position, referred to as the "autorotation position",in which said control unit (2) generates a control command to control a current collective pitch of the blades (13) of said main rotor (11) said "autorotation collective pitch".