Feed-Forward Rotor Speed Control for Aircraft Efficiency

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Solution Overview

Problem

Existing rotor speed control systems for aircraft, such as helicopters, face challenges in efficiently managing rotor speed reductions during high-speed operations, which can decrease maneuverability and lead to performance constraints like tip clearance and hub loads, while also requiring rapid adjustments to maintain stability and safety.

Innovation Solution

A computer-implemented feed-forward rotor speed command system that processes flight commands to generate load factor changes, which are then used to adjust rotor speed, allowing for incremental changes and maintaining sufficient rotor speed for maneuverability and safety, by integrating with flight control systems to provide real-time adjustments based on pilot or autonomous commands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If rotor speed is reduced to increase efficiency, then fuel economy and range improve, but maneuverability and safety decrease

Engineering Contradiction:
Improvefuel efficiencyVSAvoidmaneuverability
Core Design Contradiction:
Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts rotor speed based on real-time flight conditions and pilot commands. The feed-forward control mechanism continuously modifies rotor speed commands to maintain optimal performance across varying operational states, enabling the system to adapt between efficiency-oriented low-speed cruise and maneuverability-oriented high-speed operations

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the rotor speed parameter dynamically based on flight phase and pilot intent. By modifying the rotor speed command parameter in real-time through feed-forward control, the system optimizes fuel efficiency during steady-state flight while restoring full speed capability when maneuvers are required

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If rotor speed is reduced for efficiency, then drag and noise decrease, but system response to maneuvers slows

Engineering Contradiction:
Improvenoise and dragVSAvoidresponse speed
Core Design Contradiction:
Object-generated harmful factorsVSSpeed

Solution Approach 1:

The feed-forward control system performs preliminary action by anticipating maneuver requirements and proactively adjusting rotor speed before the maneuver is fully initiated. This allows the system to maintain lower speeds for reduced drag and noise during cruise, while being prepared to rapidly increase speed when maneuvers are commanded

Inventive Principle:
Principle #10Preliminary action

3Use of energy by moving object

If rotor speed is reduced below nominal, then fuel economy improves, but tip clearance and hub loads constraints are violated

Engineering Contradiction:
Improvefuel economyVSAvoidconstraint satisfaction
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The system employs feedback control mechanisms that continuously monitor flight conditions, rotor dynamics, and constraint parameters. This feedback loop ensures that rotor speed reductions maintain fuel economy while automatically preventing violations of tip clearance and hub loads constraints by adjusting speed commands within safe operational boundaries

Inventive Principle:
Principle #23Feedback

4Reliability

If rapid rotor speed adjustments are made to maintain stability, then safety is maintained, but system complexity increases

Engineering Contradiction:
Improveflight stabilityVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The feed-forward control system performs preliminary adjustments based on anticipated flight condition changes, reducing the need for complex reactive control algorithms. By proactively managing rotor speed transitions, the system maintains stability while avoiding the need for overly complex feedback control mechanisms

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3326911B1Rotor speed control using a feed-forward rotor speed command
Publication Date: 2019.07.10 SIKORSKY AIRCRAFT CORP
  • EP3326911B1 patent drawingFigure 1
  • EP3326911B1 patent drawingFigure 2
  • EP3326911B1 patent drawingFigure 3

AI summary

Examples of rotor speed reduction using a feed-forward rotor speed control command are provided. In one example, a computer-implemented method includes: receiving, by a processing device, flight command indicative of a change in a flight characteristic of an aircraft comprising a rotor; generating, by the processing device, a change in load factor based on the flight command; generating, by the processing device, a change in rotor speed based on the change in load factor (302); generating, by the processing device, a rotor speed command (304) based on the change in rotor speed to a flight controller to cause the aircraft to change a rotor speed of the rotor; and changing, by the processing device, the rotor speed of the rotor responsive to the rotor speed command.