Concentric Rotor Control System for Compact Aircraft

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Solution Overview

Problem

Existing aircraft with limited space between the transmission and rotor face challenges in providing effective collective and cyclic rotor control due to spatial constraints.

Innovation Solution

A concentric rotor control system utilizing internal collective and cyclic control rods within the rotor shaft, coupled with servos to receive flight inputs and actuate control rods for precise control of rotor blades, allowing for compact and efficient control mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional swashplate assembly is used for rotor control, then collective and cyclic control can be achieved, but the space required between transmission and rotor increases

Engineering Contradiction:

Improverotor control capabilityVSAvoidspace between transmission and rotor

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The patent implements nested control rods where the cyclic control rod is positioned inside the collective control rod, both running concentrically through the rotor shaft. This nesting arrangement allows both cyclic and collective control functions to be achieved within a compact volume, eliminating the need for a large swashplate assembly and freeing up space between the transmission and rotor.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent transitions from a traditional lateral swashplate arrangement to a longitudinal control rod arrangement that runs through the rotor shaft axis. By reorienting the control mechanism along the longitudinal dimension rather than requiring lateral space, the system achieves full control functionality within the limited radial space available between transmission and rotor.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Volume of moving object

If control rods are positioned internal to the rotor shaft, then space requirements are minimized, but the complexity of actuation increases

Engineering Contradiction:

Improvespace between transmission and rotorVSAvoidcontrol rod actuation mechanism

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent introduces servo actuators as intermediary devices that convert electrical control signals into mechanical motion of the control rods. The servos receive flight inputs and automatically actuate the collective and cyclic control rods to the appropriate positions, eliminating the need for complex mechanical linkages and reducing overall system complexity despite the internal positioning of control rods.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional mechanical control linkages with electro-mechanical servo actuators. Instead of using complex mechanical systems to position the control rods, electrical signals are used to drive the servos, which then mechanically position the rods. This substitution simplifies the actuation mechanism while maintaining precise control capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8801380B2Concentric rotor control system

Publication Date: 2014.08.12 SIKORSKY AIRCRAFT CORP

AI summary

A rotor control system including a collective control rod positioned internal to a rotor shaft, the rotor shaft for imparting torque to rotor blades; and a cyclic control rod positioned internal to and concentric with the collective control rod.