Offset Wing-Wake Nacelle Layout for Lower Drag Aircraft
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Solution Overview
Problem
Aircraft turbojet engines positioned under the wings limit nacelle size due to ground clearance requirements, causing increased aerodynamic drag and mechanical-aerodynamic dependence on the wings, leading to distortions and vibrations.
Innovation Solution
Integrate nacelles partially or fully within the aircraft fuselage, positioning the air intake edge of the nacelle contiguous with the wing's trailing edge to reduce drag and vibrations, using a propulsion assembly with blowers and gas turbines, and optionally connecting to the wing via pylons for support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the turbojet engines are mounted under the wings in nacelles, then the propulsion system is structurally supported by the wings, but the nacelle size is limited due to ground clearance requirements and the nacelle is contained within the wing's boundary layer increasing aerodynamic drag and causing distortions
Solution Approach 1:
The nacelle is repositioned from a conventional under-wing location to an offset position where it is supported by the fuselage rather than the wing. This spatial reconfiguration in another dimension allows the nacelle to be positioned outside the wing's boundary layer while maintaining structural support through alternative mounting arrangements.
2Strength
If the nacelle is structurally integrated into the aircraft wing, then mechanical support is provided, but the nacelle and wing become mechanically and aerodynamically dependent on each other causing vibrations and drag
Solution Approach 1:
The nacelle is extracted from the wing structure and repositioned to an offset location where it is supported by the fuselage. This separation removes the mechanical and aerodynamic coupling between the nacelle and wing, eliminating the harmful dependence while maintaining structural support through alternative means.
3Length of moving object
If the air intake edge of the nacelle is positioned away from the wing trailing edge, then ground clearance is improved, but the wing's aerodynamic drag increases and the nacelle enters the boundary layer
Solution Approach 1:
The nacelle is positioned in an offset location with its air intake edge contiguous with the wing trailing edge, creating a vertical offset that provides ground clearance while maintaining aerodynamic efficiency. This three-dimensional positioning allows the nacelle to be outside the boundary layer while preserving favorable airflow conditions.
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
Reduces aerodynamic drag and mechanical vibrations, enhances lift, and compensates for propulsion system mass through differential airflow, improving overall aircraft performance.
Implementation Method 1
this particular positioning makes it possible to ensure, through the differential in airflow speed between the upper and lower surfaces of the wing, the aerodynamic lift of the nacelle
Implementation Method 2
the viscous friction effect of the airflow over the aircraft wings manifests as the formation of a boundary layer around them
Implementation Method 3
helps to limit the wing's aerodynamic drag while significantly reducing distortions in the propulsion system
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to an aircraft (1) comprising a fuselage (10) which carries a nacelle (3) of the aircraft (1) which is offset from a wing (2) of the aircraft (1), the nacelle (3) forming an air inlet fairing of a propulsion assembly (4), the nacelle (3) comprising a lower wall (31) and an upper wall (30) which together delimit the height of the nacelle (3), the air inlet edge (31a) of the lower wall (31) being contiguous with a trailing edge (23) of the wing (2).