Unducted Fan Propulsor Positioning for Wing-Induced Thrust Gain

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Solution Overview

Problem

Winged aircraft with undermounted propulsors face increased drag and weight penalties due to the installation of turboprop engines, particularly with unducted fan propulsors, which require higher thrust and fuel flow without a corresponding increase in 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 without increasing power requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If an unducted fan propulsor is installed on a winged aircraft, then thrust is generated to propel the aircraft, but installation penalties including increased drag and weight occur

Engineering Contradiction:

ImprovethrustVSAvoiddrag

Core Design Contradiction:

ForceVSLoss of energy

Solution Approach 1:

The patent positions the unducted fan propulsor at a specific location relative to the wing's effective quarter chord point, where the high-pressure air flow induced by the wing is utilized to offset the interference and scrubbing drag. This converts the harmful drag effect into a beneficial thrust enhancement, allowing the propulsor to leverage the wing's pressure differential to reduce net drag penalties.

Inventive Principle:

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

Solution Approach 2:

The patent defines a specific spatial relationship between the propulsor and the wing, positioning the propulsor at a location determined by the effective quarter chord point and guide vane geometry. This localized positioning optimizes the interaction between the propulsor and wing-generated flow fields, creating favorable pressure differentials that reduce drag while maintaining thrust.

Inventive Principle:

Principle #3Local quality

2Force

If the size of the undermounted propulsor is increased, then thrust capability is improved, but installation penalties such as increased weight increase

Engineering Contradiction:

Improvethrust capabilityVSAvoidpropulsor weight

Core Design Contradiction:

ForceVSWeight of moving object

Solution Approach 1:

The patent changes the positional parameters of the propulsor relative to the wing structure, specifically defining the propulsor location based on the effective quarter chord point and guide vane geometry. This parameter optimization allows the propulsor to operate more efficiently at reduced sizes, as the favorable positioning compensates for the reduced thrust area, thereby reducing weight while maintaining thrust capability.

Inventive Principle:

Principle #35Parameter changes

3Force

If the propulsor is positioned to offset interference and scrubbing drag, then thrust delivery is enhanced, but the positioning complexity increases

Engineering Contradiction:

Improvethrust deliveryVSAvoidpositioning complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The patent performs preliminary geometric analysis to define the optimal propulsor position before the aircraft is assembled. By pre-calculating the position relative to the effective quarter chord point and guide vane geometry, the complex positioning problem is resolved in the design phase, simplifying the actual installation and operation while ensuring optimal thrust delivery and drag offset.

Inventive Principle:

Principle #10Preliminary action

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 enhances thrust delivery and reduces drag, improving aircraft performance and fuel efficiency by leveraging high-pressure air flow induced by the wing, while minimizing noise and interference effects.

Implementation Method 1

Aircraft with a fan propulsor includes a fuselage, wings, and an unducted fan propulsor that provides thrust to the aircraft

Methodology Applied

Scientific EffectThrust generation: Jet

Implementation Method 2

enhances thrust delivery and reduces drag, improving aircraft performance and fuel efficiency by leveraging high-pressure air flow induced by the wing

Methodology Applied

Scientific EffectAerodynamic pressure differential: Aerofoil

Implementation Method 3

Methodology Applied

Scientific EffectDrag reduction: Drag

Data Source

PatentUS20260015090A1Aircraft with an unducted fan propulsor

Publication Date: 2026.01.15 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.