Rotorcraft VRS Protection Using Vertical Speed and Power Margin
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Solution Overview
Problem
Rotorcrafts face challenges in avoiding the vortex ring state (VRS) during low airspeed operations, particularly at high vertical velocities, where control limitations and restricted ability to arrest descent rates can occur, especially in poor visibility or high workload conditions.
Innovation Solution
A method and system for monitoring the vertical speed of a rotorcraft and comparing it to a safety threshold, performing VRS avoidance by determining the power margin available from the engines, limiting vertical speed if the power margin exceeds a threshold, and increasing forward airspeed if the power margin does not exceed the threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If vertical speed is increased to improve flight performance, then flight capability is enhanced, but the risk of entering vortex ring state increases
Solution Approach 1:
The flight control system proactively monitors vertical speed and power margin parameters before the rotorcraft enters the VRS region. When the vertical speed approaches the VRS boundary, the system preemptively adjusts flight parameters (limiting vertical speed or increasing forward airspeed) to prevent entry into the dangerous flight regime, rather than reacting after VRS has already occurred.
2Reliability
If automated VRS protection is implemented to improve flight safety, then pilot workload is reduced, but system complexity increases
Solution Approach 1:
The flight control system continuously monitors vertical speed and power margin parameters, comparing them against predefined VRS boundaries. Based on this feedback loop, the system automatically adjusts flight parameters when approaching VRS conditions. This closed-loop control provides automated protection while maintaining manageable system complexity through straightforward sensor integration and control logic.
3Measurement precision
If power margin is used to determine VRS avoidance strategy, then flight control precision is improved, but measurement and calculation complexity increases
Solution Approach 1:
The system utilizes power margin as a key parameter to dynamically adjust the VRS avoidance strategy. By monitoring power margin alongside vertical speed, the control system can distinguish between different flight scenarios and apply appropriate correction actions. This parameter-based approach enhances measurement precision while keeping calculations manageable through direct integration of existing engine and flight parameter data.
Data Source
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AI summary
The present invention relates to a method (900) for protecting a rotorcraft from entering a vortex ring state. The method (900) comprises: monitoring (902) a vertical speed and a forward speed of a rotorcraft; determining (908) whether to perform vortex ring state (VRS) avoidance according to at least one of the vertical speed and the forward airspeed of the rotorcraft; and performing (912, 914), in response to determining to perform the VRS avoidance, control of one or more flight parameters of the rotorcraft. Also disclosed are a device configured to carry out the method (900) and a rotorcraft comprising a flight control computer configured to carry out the method (900).