Hybrid Helicopter Propeller Pitch Control for Engine-Failure Autorotation
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Solution Overview
Problem
Hybrid helicopters face significant vibrations and aerodynamic loads on the lift rotor during engine failures, which can lead to rapid speed reduction and increased pilot workload, as existing methods require quick manual intervention to manage autorotation.
Innovation Solution
An automatic piloting system that measures forward speed and implements an emergency mode to reduce propeller pitch, allowing propellers to supply power to the lift rotor, thereby reducing speed loss and minimizing vibrations and aerodynamic loads, allowing the pilot to focus on safe landing or deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If manual autorotation control is implemented during engine failure, then pilot response time is reduced, but pilot workload increases and rapid speed reduction occurs
Solution Approach 1:
The system enables self-service by automatically detecting engine failure and adjusting propeller pitch to generate driving torque on the lift rotor, allowing the aircraft to maintain rotor speed without continuous pilot intervention. The automatic piloting system monitors engine parameters and autonomously implements the emergency procedure.
Solution Approach 2:
The manual mechanical control system is replaced with an automatic piloting system that uses sensors and actuators to detect engine failure and adjust propeller pitch. This substitution eliminates the need for rapid manual lever operations and reduces pilot workload while maintaining rotor speed.
2Power
If propeller pitch is rapidly reduced during engine failure, then power balance is restored, but vibrations and aerodynamic loads on lift rotor increase
Solution Approach 1:
The system uses feedback by continuously monitoring the lift rotor speed and automatically adjusting propeller pitch to maintain a setpoint speed. The automatic piloting computer receives speed measurements and modifies propeller pitch accordingly, creating a closed-loop control system that restores power balance while minimizing harmful vibrations and loads.
Solution Approach 2:
The system changes the propeller pitch parameter automatically in response to engine failure. By adjusting the pitch angle to an optimal value, the propellers transition from consuming power to producing driving torque, restoring power balance while controlling vibrations and aerodynamic loads through precise parameter management.
3Stability of the object's composition
If automatic piloting system manages propeller pitch, then speed stability is maintained, but system complexity increases
Solution Approach 1:
The automatic piloting system performs multiple functions: it monitors engine parameters, detects failures, calculates optimal propeller pitch, and controls pitch actuators. By consolidating these functions into a single multi-functional system, the patent maintains speed stability while managing complexity through integration rather than adding separate dedicated systems.
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 reduces pilot workload and increases safety by automatically managing propeller pitch to maintain lift rotor speed and stability during engine failures, enabling gradual deceleration or maintaining high speed without altitude loss.
Implementation Method 1
automatically reducing a pitch of the propeller blades to a pitch value making the propeller produce a motive power which drives the rotor
Data Source
AI summary
The present invention relates to a control method in case of engine failure of a hybrid helicopter having a power plant connected to at least one lift rotor and to at least one propeller, said lift rotor having a plurality of first blades and said at least one propeller having a plurality of second blades. The method comprises the following steps: (i) measuring a forward speed of the hybrid helicopter, (ii) on condition that said forward speed is greater than a first speed threshold and that each engine has failed, automatically implementing a first emergency piloting mode comprising a step for automatic reduction by an automatic piloting system of a pitch of said second blades toward an objective pitch making said at least one propeller produce a motive power which is transmitted to the lift rotor.