Swashplateless Rotor Hub with Delta-3 Restraint

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Rotary-wing aircraft designers face challenges in controlling rotor blade pitch without swashplates, which eliminates the safety benefits of the delta-3 angle, a critical safety consideration in rotor hub design, especially during forward flight.

Innovation Solution

A swashplateless rotor hub assembly that incorporates a pitch actuator and a delta-3 restraint anchored to the mast, allowing for active control of rotor blade pitch and maintaining the delta-3 angle even when the pitch actuator fails, providing an instantaneous blade pitch-flap coupling response.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a swashplate is used to control blade pitch, then blade pitch can be changed in response to blade lift and flapping differences, but the system complexity increases and independent blade control is not possible

Engineering Contradiction:

ImproveIndependent blade pitch controlVSAvoidSwashplate mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention divides the pitch control function into two independent parts: (1) a swashplateless active pitch actuator that provides independent control of each blade's pitch angle, and (2) a passive delta-3 restraint mechanism that independently maintains the delta-3 angle for safety. This segmentation allows each subsystem to perform its specific function without the complexity of a traditional swashplate that tries to do both simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pitch horn serves as an intermediary element that couples the active pitch actuator to the blade while also interfacing with the passive delta-3 restraint. This intermediary structure allows the active actuator to control pitch independently while the passive restraint simultaneously maintains the safety angle, resolving the contradiction between independent control and system simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a swashplateless active blade control system is used, then independent pitch control is achieved, but the safety benefits of the delta-3 angle are eliminated

Engineering Contradiction:

ImproveIndependent blade pitch controlVSAvoidDelta-3 angle safety

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The passive delta-3 restraint mechanism is pre-configured to automatically maintain the delta-3 angle whenever the active pitch actuator fails or is not actively controlling the blade. This preliminary safety mechanism is built into the structure itself, ensuring that the safety benefit is automatically activated without requiring additional active control systems or complex sensing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention applies different control qualities to different aspects of blade pitch: the active pitch actuator provides precise, independently controllable pitch adjustment when needed, while the passive delta-3 restraint provides a fixed, safety-oriented pitch constraint. This local differentiation of control quality allows both independent control capability and safety benefits to coexist.

Inventive Principle:

Principle #3Local quality

3Reliability

If a passive delta-3 restraint is used, then safety is maintained, but instantaneous pitch-flap coupling response is not achieved

Engineering Contradiction:

ImproveDelta-3 angle safetyVSAvoidPitch-flap coupling response

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The invention replaces complex active mechanical control systems with a purely passive mechanical restraint mechanism for maintaining the delta-3 angle. This passive mechanical system uses the natural geometry and forces of the pitch horn and restraint linkage to automatically maintain the safety angle without requiring sensors, actuators, or control electronics, thereby achieving instantaneous response.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The passive delta-3 restraint mechanism is self-regulating and automatically maintains the delta-3 angle through its own mechanical geometry and the forces acting on the blade during flight. It requires no external power, control signals, or active intervention to function, providing instantaneous pitch-flap coupling response purely through its mechanical design.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9476312B2Swashplateless active blade pitch control with a mechanical delta-3 restraint having an instantaneous blade pitch-flap coupling response

Publication Date: 2016.10.25 TEXTRON INNOVATIONS INC

AI summary

An apparatus comprising a hub configured to couple to a mast, a grip configured to couple to the hub and a rotor blade, a pitch actuator coupled to the grip and configured to change a pitch of the rotor blade relative to the mast, and a delta-3 restraint coupled to the pitch actuator, wherein the delta-3 restraint is fixed relative to the mast. An apparatus comprising a hub configured to couple to a mast, a grip configured to couple to the hub and a rotor blade, a pitch actuator coupled to the grip and configured to change a pitch of the rotor blade relative to the mast, and a delta-3 restraint coupled to the pitch actuator, wherein the delta-3 restraint is configured to control the pitch of the blade relative to the mast when the pitch actuator fails, and wherein the delta-3 restraint provides an instantaneous blade pitch-flap coupling response.