Aircraft Engine Mounting System Reducing Core Bending

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Solution Overview

Problem

Existing engine mount systems for turbofan engines induce bending moments in the engine core due to thrust and aerodynamic loading, which reduces efficiency and causes stress on the aircraft structure.

Innovation Solution

The proposed engine mounting system includes a first forward mount, an aft mount, and a second forward mount, where the second forward mount is offset to react longitudinal forces, thereby reducing pitch moments and eliminating backbone bending. This configuration also incorporates a fluidic torque restraint device to decouple vertical loads and roll moments, allowing the aft mount to react loads only after a defined pitch deflection, providing redundancy and minimizing weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a single forward mount and aft mount configuration is used to react engine loads, then the engine can be supported, but bending moments are induced in the engine core due to thrust and aerodynamic loading

Engineering Contradiction:

Improveengine core bending momentVSAvoidengine mount system performance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The forward mount is divided into two separate mounts: a first forward mount that reacts vertical and lateral loads, and a second forward mount offset from the first that reacts longitudinal thrust forces. This segmentation creates separate load paths that eliminate the coupling between thrust and vertical load reactions, thereby eliminating bending moments in the engine core while maintaining overall structural reliability.

Inventive Principle:

Principle #1Segmentation

2Force

If thrust links are configured to react engine thrust, then thrust loads are supported, but pitch moments are induced that must be reacted by the forward and aft mounts as vertical loads

Engineering Contradiction:

Improvethrust reactionVSAvoidvertical loading at rear mount

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The second forward mount is positioned offset from the first forward mount in a direction transverse to the engine thrust line. This spatial offset creates a moment arm that allows the second mount to react pitch moments generated by thrust about the lateral axis, thereby eliminating the need for the aft mount to react vertical loads due to thrust while maintaining proper thrust force reaction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If the nacelle inlet is inclined relative to airflow during climb, then aerodynamic pitch moment is induced on the inlet, but this moment transmits further backbone bending to the engine

Engineering Contradiction:

Improvenacelle angle relative to airflowVSAvoidbackbone bending

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The system extracts the function of reacting aerodynamic pitch moments from the engine core structure by providing a dedicated load path through the offset second forward mount. This mount specifically handles pitch moments about the lateral axis, separating this function from the engine backbone and eliminating the transmission of aerodynamic-induced pitch moments to the engine core, thereby reducing backbone bending while maintaining adaptability to various flight conditions.

Inventive Principle:

Principle #2Taking out (Extraction)

4Strength

If additional mounts are added to eliminate bending moments, then engine core stress is reduced, but system complexity and weight increase

Engineering Contradiction:

Improveengine core stress reductionVSAvoidmount system configuration

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The second forward mount performs multiple functions: it reacts longitudinal thrust forces, reacts pitch moments about the lateral axis, and provides a dedicated load path that eliminates the need for complex thrust link angle adjustments. By consolidating these functions into a single offset mount, the system reduces overall complexity compared to alternative solutions that would require multiple adjustment mechanisms while achieving the goal of reducing engine core stress.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3497017B1Mounting systems for aircraft engines

Publication Date: 2021.11.10 LORD CORP

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Figure 2A

AI summary

Engine mounting systems and methods that reduce engine core bending provide a first forward mount (130) connectable to a forward part of an engine core of an aircraft, an aft mount (150) connectable to an aft part of the core, and in a variant a second forward mount (140) connectable to the engine radially outward from the longitudinal axis of the engine with respect to the first forward mount, e.g. to a fan casing. The first forward mount reacts forces in a longitudinal, a lateral and a vertical direction. The aft mount reacts forces in the lateral direction and moments about the longitudinal direction, and in a variant vertical forces only from a predetermined pitch deflection of the engine. Stiffness values of the (first) forward and/or aft mount in the vertical direction may be reduced upon a fan blade off event. Where present, the second forward mount reacts forces in the longitudinal direction by being offset from the first forward mount such that reacting forces in the longitudinal direction by the forwards mounts reacts moments about the lateral direction.