Unducted Fan Propulsor Placement to Reduce Wing Drag
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Solution Overview
Problem
The installation of undermounted propulsors on winged aircraft leads to increased drag and weight penalties, particularly for unducted fan propulsors, due to scrubbing and interference drags, which require higher thrust and fuel flow without addressing these issues directly.
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 effects without increasing power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an undermounted propulsor is added to a winged aircraft, then thrust generation capability is improved, but drag increases due to scrubbing and interference effects
Solution Approach 1:
The patent applies preliminary action by positioning the propulsor at a predetermined optimal location relative to the wing's quarter-chord point before flight operations. This pre-positioning allows the propulsor to leverage the high-pressure air flow that naturally exists beneath the wing during cruise, thereby reducing scrubbing drag and interference effects before they can negatively impact thrust generation.
Solution Approach 2:
The patent applies local quality by optimizing the propulsor's position specifically at the quarter-chord point of the wing, where the air flow characteristics are most favorable. This localized optimization allows the propulsor to exploit the high-pressure region beneath the wing while minimizing interference with the wing's aerodynamic performance, thereby improving thrust generation without proportionally increasing drag.
2Power
If the propulsor size is increased to provide higher thrust, then thrust generation capability is improved, but weight increases
Solution Approach 1:
The patent applies parameter changes by optimizing the propulsor's position parameters (location relative to the quarter-chord point and distance from the wing surface) to maximize aerodynamic efficiency. By carefully adjusting these positional parameters, the system achieves higher thrust generation from a smaller propulsor, thereby reducing weight while maintaining or improving power output.
3Object-affected harmful factors
If the propulsor is positioned to offset interference and scrubbing effects, then drag penalties are reduced, but positioning precision requirements increase
Solution Approach 1:
The patent applies self-service by designing the propulsor mounting system to automatically position itself at the optimal location relative to the wing's quarter-chord point. The geometric relationship between the propulsor mounting points and the wing structure ensures that the propulsor naturally assumes the correct position to exploit the high-pressure air flow, reducing the need for complex active positioning systems while maintaining precision.
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 generation while reducing drag penalties, improving aircraft performance and fuel efficiency by leveraging high-pressure air flow and minimizing noise during cruise conditions.
Implementation Method 1
an unducted fan propulsor installed relative to a section of a wing or a horizontal stabilizer of the aircraft
Implementation Method 2
enhances thrust generation while reducing drag penalties, improving aircraft performance and fuel efficiency by leveraging high-pressure air flow
Data Source
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.