Unducted Fan Propulsor Placement to Offset Wing Drag

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Solution Overview

Problem

The installation of unducted fan propulsors on winged aircraft leads to increased drag and weight penalties, necessitating a solution that enhances thrust without increasing engine power.

Innovation Solution

Positioning the unducted fan propulsor relative to the aircraft's effective quarter chord point (QC) and defining a midpoint (P) between guide vanes and fan blades, optimizing the propulsor's location to offset interference and scrubbing drag.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If an unducted fan propulsor is added to a wing, then thrust is provided, but drag increases

Engineering Contradiction:

ImprovethrustVSAvoiddrag

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent positions the propulsor to utilize the wing's high-pressure low-speed flow region, converting the previously harmful interference and scrubbing drag into beneficial thrust enhancement. The propulsor is installed such that it operates in the downwash region beneath the wing, where the flow characteristics naturally enhance thrust while reducing the net drag penalty.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the installation parameters of the propulsor by defining a specific location relative to the effective quarter-chord point (QC) of the airfoil section. The propulsor is positioned with its centerline at a specific distance and angle from the QC, and its plane is oriented at a specific angle to the chord line, optimizing the interaction between the propulsor and wing flow fields.

Inventive Principle:

Principle #35Parameter changes

2Force

If the size of the undermounted propulsor increases, then thrust capability increases, but weight increases

Engineering Contradiction:

Improvethrust capabilityVSAvoidweight

Core Design Contradiction:

ForceVSWeight of moving object

Solution Approach 1:

The patent converts the previously harmful interference drag into a beneficial effect by positioning the propulsor to operate in the wing's high-pressure region. This allows the propulsor to generate additional thrust from the existing wing flow field, effectively increasing thrust capability without requiring a larger (and heavier) propulsor.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The wing structure serves multiple functions: it provides lift as before, and additionally creates a high-pressure low-speed flow region that enhances the propulsor's thrust capability. The propulsor installation utilizes the wing's flow field for dual purposes, reducing the need for separate thrust-generation components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 positioning strategy increases thrust without increasing power requirements, improving aircraft performance and reducing noise during cruise conditions.

Implementation Method 1

An aircraft includes a fuselage, wings and/or stabilizers, and two or more unducted fan propulsors mounted to the wings and/or stabilizers. The unducted fan propulsors provide thrust to the aircraft.

Methodology Applied

Scientific EffectThrust generation: Jet

Implementation Method 2

Methodology Applied

Scientific EffectDrag offset through positioning: Drag

Data Source

PatentUS20260070666A1Aircraft with an unducted fan propulsor

Publication Date: 2026.03.12 GENERAL ELECTRIC CO

AI summary

The present disclosure is generally related to aircraft having one or more unducted fan propulsors at locations within specific regions relative to an airfoil, such as a wing or horizontal stabilizer. More specifically, the specific regions are located where there is a relatively higher pressure air flow beneath the wings or above a horizontal stabilizer. That higher pressure air flow can be utilized to provide increased thrust from the unducted fan propulsor.