Rotor Blade Spar Structure for Multi-Model Manufacturing

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Solution Overview

Problem

Manufacturing different rotor blades for various rotary wing aircraft models requires expensive custom tooling and machinery, occupying valuable factory space.

Innovation Solution

A rotor blade design with a spar having a substantially constant inboard height and thickness, allowing for trimming or extension to accommodate different aircraft models, and a root seal positioned outboard to facilitate easy adaptation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If custom tooling and machinery are used for each rotor blade model, then manufacturing precision and blade-specific performance are improved, but manufacturing cost and device complexity increase

Engineering Contradiction:
Improveblade manufacturing precisionVSAvoidcustom tooling and machinery
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The spar is designed with a standardized constant height section that serves as a universal interface for multiple aircraft models. This single spar design can be adapted to different blade lengths and configurations without requiring custom tooling for each model, thereby reducing device complexity while maintaining manufacturing precision through consistent dimensional controls.

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

Solution Approach 2:

The spar is divided into distinct functional sections: a constant height inboard portion that provides standardized mounting interfaces, and variable outboard portions that can be trimmed or extended. This segmentation allows the same spar to be configured for different aircraft models by modifying only the non-critical outboard sections, rather than requiring custom tooling for the entire blade.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If custom tooling is manufactured for each aircraft model, then ease of manufacture for specific models is improved, but loss of substance and manufacturing cost increase

Engineering Contradiction:
Improvemodel-specific manufacturing easeVSAvoidmaterial waste from custom tooling
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

A single spar design with standardized constant height dimensions serves multiple aircraft models, eliminating the need to manufacture custom tooling for each model. The same spar can be trimmed or extended to fit different configurations, reducing material waste associated with producing discarded custom tooling while maintaining ease of manufacture through standardized processes.

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

3Ease of manufacture

If factory space is occupied by custom machinery for each model, then manufacturing capability for specific models is improved, but productivity and space utilization worsen

Engineering Contradiction:
Improvemodel-specific manufacturing capabilityVSAvoidfactory space utilization
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The standardized spar design enables a single manufacturing setup to produce blades for multiple aircraft models by varying only the outboard length through trimming or extension. This eliminates the need for separate manufacturing lines for each model, improving factory space utilization and overall productivity while maintaining the capability to manufacture model-specific blades.

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

Data Source

PatentEP4316981B1Commonly manufactured rotor blade
Publication Date: 2025.11.19 LOCKHEED MARTIN CORP
  • EP4316981B1 patent drawingFigure 1
  • EP4316981B1 patent drawingFigure 2
  • EP4316981B1 patent drawingFigure 3A~3C

AI summary

A method of modifying a rotor blade is provided for a rotor blade including a spar having an inboard portion with a substantially constant overall height, the inboard portion further including a top layer having a substantially constant first thickness and a bottom layer having a substantially constant second thickness. The method includes removing a root portion of the inboard portion to thereby modify the rotor blade and installing a cuff configured to couple to the rotor blade to an aircraft.