Aircraft Horizontal Stabilizer Negative Sweep Design
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Solution Overview
Problem
High-speed aircraft designs face challenges with positive sweepback wings, which increase structural weight and aerodynamic drag due to compressibility effects, while negative sweepback wings offer aerodynamic advantages but are rarely used due to structural complications and increased lift gradients, making them unsuitable for commercial aviation, especially in stabilizer surfaces.
Innovation Solution
A horizontal stabilizer surface with a negative sweep angle is introduced, eliminating the need for a structural opening in the fuselage and maintaining aerodynamic performance by positioning the aerodynamic centre similarly to conventional configurations, allowing for reduced size, weight, and drag, while enhancing rigidity and reducing deformations under aerodynamic loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If positive sweepback wings are used in high-speed aircraft, then structural weight is reduced, but aerodynamic drag increases due to compressibility effects
Solution Approach 1:
The patent changes the sweepback parameter from positive to negative, fundamentally altering the geometric configuration of the stabilizer surface. This parameter change allows the leading edge to be positioned forward of the quarter-chord line, thereby modifying airflow characteristics and reducing compressibility effects at high speeds while maintaining structural efficiency
2Object-generated harmful factors
If negative sweepback wings are used, then aerodynamic drag is reduced, but structural weight increases due to higher gust loads
Solution Approach 1:
The patent applies local quality by implementing negative sweepback specifically on the horizontal stabilizer surface rather than on the entire wing structure. This localized application allows the stabilizer to benefit from reduced aerodynamic drag and improved high-speed performance without subjecting the main wing structure to the increased gust loads that would necessitate additional weight
Solution Approach 2:
The patent segments the aircraft structure by applying different sweepback configurations to different components: the horizontal stabilizer uses negative sweepback for aerodynamic efficiency at high speeds, while the main wings maintain positive or zero sweepback to avoid excessive gust loads. This segmentation allows each component to be optimized for its specific functional requirements
3Object-generated harmful factors
If negative sweepback horizontal stabilizer is used, then aerodynamic performance is improved, but fuselage structural complexity increases due to connection requirements
Solution Approach 1:
The patent incorporates the fuselage frame structure in advance during the design phase, positioning it to directly support the horizontal stabilizer at the appropriate location. This preliminary structural preparation eliminates the need for subsequent structural openings or complex retrofits, as the fuselage is pre-configured to accommodate the negative sweepback stabilizer configuration
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
The configuration reduces structural weight and increases the effectiveness of the stabilizer by minimizing deformations and maintaining aerodynamic performance, enabling a more efficient and lightweight design that mitigates the adverse effects of aerodynamic loads and turbulence.
Implementation Method 1
The aerodynamic advantage of the sweepback is that the adverse effects of compressibility, caused by the overspeed of the flow over the aerodynamic profile, which grow as the relative thickness of that profile increases, are related to the component of the airflow velocity that is essentially perpendicular to the line of 25% of the chord of the airfoil of the aircraft.
Implementation Method 2
the air movement in the direction of the wingspan is from tip to root in the case of an airfoil with negative sweepback, which results in the possibility of achieving larger angles of stall of aerodynamic lift than in the case of positive sweepback airfoils
Data Source
AI summary
Aircraft horizontal stabilizer surface (8) in which the sweep angle (40) of this surface (8), where this angle (40) is the one formed by the projection of the reference line of points located at 25% of the local chord (19) of the horizontal stabilizer surface (8) on a plane perpendicular to the aircraft plane of symmetry (21), and which also contains this plane to the flight direction of the aircraft with respect to the aircraft plane of symmetry (21), is less than 90 degrees, with this angle (40) being measured in the flight direction of the aircraft. In addition, the structural connection of this horizontal stabilizer surface (8) to the aircraft fuselage (1) is located at a closing frame (13) of this fuselage (1).