Negative Torsion Variable Paddle for Rotor Craft

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Solution Overview

Problem

Existing tilt rotor designs face challenges in achieving efficient performance in both helicopter and fixed-wing modes due to conflicting design requirements for rotor paddles, such as managing negative torsion to avoid root stall while ensuring adequate lift during high-speed forward flight.

Innovation Solution

The implementation of a negative torsion variable paddle system using a mechanical structure that includes a composite paddle with a rigid first paddle and a second paddle featuring a deformed layer, cascade, and flexible skin, allowing for torsional variation without changing the rotor radius.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If large negative torsion is applied to the rotor paddle, then hovering efficiency in helicopter mode is improved, but root stall occurs

Engineering Contradiction:

Improvehovering efficiencyVSAvoidroot stall

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The rotor paddle employs variable torsion technology that allows the torsion angle to be dynamically adjusted based on flight mode. In helicopter mode, the system optimizes negative torsion distribution to improve hovering efficiency while preventing excessive torsion that would cause root stall. The torsion angle can be varied along the paddle span and adjusted in real-time according to operational requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the torsion parameter of the rotor paddle to resolve the contradiction. By applying negative torsion within an optimized range and distribution pattern, the system improves hovering efficiency without exceeding the threshold that would cause root stall. The torsion parameter is carefully controlled to balance performance and reliability.

Inventive Principle:

Principle #35Parameter changes

2Force

If large paddle negative torsion is used, then lift generation in fixed-wing mode is improved, but rotor structure complexity increases

Engineering Contradiction:

Improvelift generationVSAvoidrotor structure

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The rotor paddle employs variable torsion technology that allows the torsion angle to be dynamically adjusted based on flight mode. In fixed-wing mode, the system applies appropriate negative torsion to ensure each airfoil profile has a high angle of attack for sufficient lift generation, while in helicopter mode, the torsion is optimized for hovering efficiency. This dynamic adjustment avoids the need for excessively complex structural designs.

Inventive Principle:

Principle #15Dynamics

3Force

If rotor speed is increased, then lift in helicopter mode is improved, but energy consumption in fixed-wing mode increases

Engineering Contradiction:

ImproveliftVSAvoidenergy consumption

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts rotor speed according to flight mode. In helicopter mode, high rotor speed is maintained to generate sufficient lift for vertical take-off and hovering. In fixed-wing mode, the rotor speed is reduced to minimize energy consumption and resistance, while variable torsion compensation ensures adequate lift generation. This dynamic speed adjustment optimizes the trade-off between lift and energy consumption.

Inventive Principle:

Principle #15Dynamics

4Power

If rotor radius is shortened, then propulsion performance in fixed-wing mode is improved, but lift generation in helicopter mode deteriorates

Engineering Contradiction:

Improvepropulsion performanceVSAvoidlift generation

Core Design Contradiction:

PowerVSForce

Solution Approach 1:

The invention employs variable torsion technology that compensates for the reduced rotor radius effect. Even with a shorter rotor radius that improves fixed-wing propulsion performance, the system applies optimized negative torsion distribution to maintain adequate lift generation in helicopter mode. The variable torsion adjusts the aerodynamic characteristics of the paddle to balance the trade-off between propulsion and lift generation.

Inventive Principle:

Principle #15Dynamics

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

This solution enhances the adaptability and reliability of the rotor craft by enabling efficient torsional variation of the composite paddle, improving flight performance across different modes without compromising structural strength or increasing the rotor's radius.

Implementation Method 1

the deformed layer is made of elastic materials

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS12286220B2Rotor craft and negative torsion variable paddle thereof

Publication Date: 2025.04.29 NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

AI summary

The present disclosure provides a negative torsion variable paddle and a control assembly thereof. The paddle includes rigid first paddles and rigid second paddles. When a driver pushes a root railing edge, the first paddle is not flexibly deformed, and the second paddle is torsionally deformed with a laminated elastomer structure between cascades to realize relative rotation at both ends of the second paddle, so that a flexible skin maintains airfoil contours, and the whole torsional degree of the paddle is changed. The present disclosure also provides a rotor craft including the negative torsion variable paddle.