Multi-Rotorcraft Pitch Control for Redundant Autorotation Landing

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Solution Overview

Problem

Existing rotorcraft technologies lack improved technical capabilities, particularly in terms of flight redundancy, energy efficiency, maneuverability, and safe emergency landing capabilities.

Innovation Solution

A rotorcraft design featuring at least three rotor systems with individually controllable collective and cyclic rotor blade pitches, a forward propulsion unit, and a flight control system that enables independent control of each rotor system, including freewheel arrangements for autorotation, allowing for safe emergency landings and efficient cruising.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rotorcraft includes at least three rotor systems with individually controllable collective and cyclic rotor blade pitches, then flight redundancy and maneuverability are improved, but device complexity increases

Engineering Contradiction:
Improveflight redundancyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The rotorcraft is divided into at least three independent rotor systems, each with its own mast, rotor blades, and control mechanisms. This segmentation allows individual rotor systems to fail independently while maintaining overall flight capability, as the remaining functional rotors can compensate for failures. Each rotor system operates semi-independently with individual collective and cyclic pitch controls, enabling redundant control authority distribution.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different rotor systems are equipped with different levels of control capability. At least one rotor system has both individual collective and cyclic pitch control, while other rotor systems have individual collective pitch control. This local differentiation optimizes the balance between redundancy and complexity by providing enhanced control where needed while maintaining simpler controls elsewhere.

Inventive Principle:
Principle #3Local quality

2Use of energy by moving object

If electric rotor motors are used to drive rotor masts without freewheel mechanisms, then direct drive efficiency is improved, but ability to autorotate during power failure is reduced

Engineering Contradiction:
Improveenergy efficiencyVSAvoidemergency landing capability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The rotor systems are designed with dynamic adaptability through individually controllable collective and cyclic rotor blade pitches. During normal operation, electric motors provide efficient direct drive. During emergency conditions, the system dynamically transitions to autorotation mode by adjusting blade pitches to capture aerodynamic energy, allowing the rotorcraft to maintain control and perform safe landings despite power failures.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The rotor blade pitch parameters can be dynamically adjusted during flight. The individual collective pitch control allows each rotor system to optimize its blade angle for either motor-driven efficiency or autorotation effectiveness. This parameter flexibility enables the system to adapt to different operational modes and maintain performance across varying conditions.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If at least one rotor system has individually controllable cyclic rotor blade pitch, then steering capability is improved, but device complexity increases

Engineering Contradiction:
Improvesteering capabilityVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

Cyclic pitch control capability is segmented and distributed to at least one rotor system rather than being centralized. This allows the rotorcraft to achieve steering functionality through differential control of individual rotor systems, providing redundant steering authority while maintaining manageable complexity by limiting cyclic control to where it provides maximum benefit.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The rotor system with individually controllable cyclic pitch serves multiple functions: it provides steering control, contributes to attitude control, and offers redundant control authority for emergency maneuvers. This multi-functionality justifies the added complexity by delivering diverse operational benefits from a single control mechanism.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 rotorcraft achieves flight redundancy, enhanced maneuverability, reduced energy consumption, and safe emergency landings, with the ability to transition smoothly between flight phases without risking stability, even in power failures.

Implementation Method 1

an electric rotor motor coupled to the mast for driving the mast

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 2

a freewheel mechanism for driving the main mast such that the main mast can freewheel autorotate without being driven by the main motor

Methodology Applied
Scientific EffectAutorotation: Angular Momentum Conservation

Data Source

PatentEP4217273B1rotorcraft
Publication Date: 2026.03.04 EFIX AVIATION LTD
  • EP4217273B1 patent drawingFigure 1A~1B
  • EP4217273B1 patent drawingFigure 2A~2B
  • EP4217273B1 patent drawingFigure 3A~3B

AI summary

Rotorcraft including a fuselage, at least three rotor system arms, a forward propulsion unit for providing forward propulsion to the rotorcraft and a flight control system. Each rotor system arm has a rotor system including a mast having at least two rotor blades and an electric rotor motor coupled to the mast for driving the mast whereupon the rotor blades act as a rotating rotor disc. Each rotor system has an individually controllable collective rotor blade pitch. At least one rotor system has a controllable cyclic rotor blade pitch. The flight control system controls the at least three electric rotor motors, the collective rotor blade pitch of each rotor system, the cyclic rotor blade pitch of the at least one rotor system and the forward propulsion unit in response to an input control indicating a desired maneuver to operate the rotorcraft for takeoff, flight and landing.