Composite Tail Boom Stiffening Framework

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Solution Overview

Problem

Current composite tail boom designs for aircraft face challenges in weight efficiency, cost, and structural stability due to the use of monocoque or sandwich structures, which are either not weight-efficient or require complex production and are sensitive to impact damage.

Innovation Solution

A semi-monocoque design with a stressed skin and a stiffening framework, featuring rod-shaped and ring-shaped stiffening elements between the outer and inner skins, eliminating the need for adhesive materials and simplifying manufacturing, while providing enhanced longitudinal and hoop bending stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If monocoque or sandwich structures are used for composite tail boom, then structural stability is improved, but weight efficiency deteriorates and production complexity increases

Engineering Contradiction:

Improvestructural stabilityVSAvoidweight efficiency

Core Design Contradiction:

Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The tail boom is divided into an outer skin, inner skin, and discrete stiffening elements (longitudinal and transverse) that are separately manufactured and then assembled together. This segmentation allows each component to be optimized independently and facilitates easier manufacturing and repair compared to monolithic monocoque structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite materials arranged in a semi-monocoque configuration with distinct skin layers and stiffening elements. This composite structure provides both structural stability and weight efficiency by distributing loads across multiple components rather than requiring a thick monolithic structure.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If monocoque or sandwich structures are used for composite tail boom, then structural stability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvestructural stabilityVSAvoidproduction complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The tail boom structure is segmented into manufacturable components (outer skin, inner skin, stiffening elements) that can be produced separately using standard composite manufacturing processes, then assembled together. This reduces the complexity of manufacturing compared to producing a single complex monocoque structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the structural parameter from a continuous monolithic structure to a discrete assembled structure, allowing for easier manufacturing, quality control, and repair while maintaining structural stability through proper design of the skin-stiffener system.

Inventive Principle:

Principle #35Parameter changes

3Strength

If adhesive materials are used to join skin and stiffening elements, then structural integrity is improved, but temperature limitations and reliability deteriorate

Engineering Contradiction:

Improvestructural integrityVSAvoidtemperature limitations

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The invention replaces the chemical bonding system (adhesives) with a mechanical bonding system (mechanical interlocking through skin thickness). This substitution eliminates the temperature limitations of adhesive materials while maintaining structural integrity through the mechanical connection between skin and stiffening elements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The stiffening elements act as intermediaries that mechanically connect the outer and inner skins, transferring loads between them without requiring adhesive materials. This intermediary mechanism provides temperature-resistant structural integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Strength

If larger cross section is used for tail boom, then bending stiffness is improved, but aerodynamic download increases

Engineering Contradiction:

Improvebending stiffnessVSAvoidaerodynamic download

Core Design Contradiction:

StrengthVSForce

Solution Approach 1:

The semi-monocoque composite structure provides high bending stiffness through the combination of thin outer and inner skins with strategically placed stiffening elements, achieving the required structural performance with a smaller cross-section than would be needed for solid structures.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The segmented structure with spaced stiffening elements creates a lightweight yet stiff configuration that achieves high bending stiffness without increasing the overall cross-sectional area, thereby minimizing aerodynamic download forces.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10457373B2Aircraft with a fuselage and a composite tail boom

Publication Date: 2019.10.29 AIRBUS HELICOPTERS DEUT GMBH

AI summary

An aircraft with a composite tail boom that comprises at least partly a tubular tail boom cone with an outer skin and an inner skin, wherein the inner skin delimits a hollow interior of the composite tail boom, wherein a plurality of rod-shaped stiffening elements and a plurality of ring-shaped stiffening elements are arranged between the outer skin and the inner skin, the plurality of rod-shaped stiffening elements being oriented in longitudinal direction of the composite tail boom and the plurality of ring-shaped stiffening elements being distributed along the longitudinal direction in the tubular tail boom cone.