Aircraft Elevator Fairing Design Minimizing Fuselage Gap
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Solution Overview
Problem
Current fairing designs for aircraft elevators maintain a non-minimal distance between the elevator and the fuselage, leading to high aerodynamic losses due to parasitic resistance, which is not optimized for all angles of action.
Innovation Solution
A design procedure that involves adjusting the fuselage surface and iteratively cutting a solid to simulate the elevator volume, minimizing the distance between the fairing and the fuselage for all elevator angles and trim angles, resulting in a smoothed fairing surface that reduces aerodynamic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fairing is designed with two intercutting planes tangent to the fuselage section, then contact between the elevator and fuselage is avoided for all elevator movements, but the distance between the fairing and fuselage is not minimized, resulting in high aerodynamic losses
Solution Approach 1:
The invention applies dynamics by considering the full range of elevator movements and trim angle variations to define a dynamic envelope. The fairing is designed to accommodate all possible positions of the elevator relative to the fuselage, ensuring contact avoidance while minimizing distance. This involves creating a virtual envelope that captures the maximum excursions of the elevator in all directions, then designing the fairing to fit within this envelope as closely as possible to the fuselage.
Solution Approach 2:
The invention transitions from a static two-plane design to a three-dimensional volumetric approach. By defining a virtual envelope that encompasses all possible elevator positions in three-dimensional space, the design can optimize the fairing shape to minimize distance to the fuselage while maintaining contact avoidance. This volumetric method allows the fairing to conform more closely to the fuselage contours in multiple directions simultaneously.
2Reliability
If a larger distance is maintained between the fairing and fuselage, then contact avoidance is ensured for all elevator angles, but aerodynamic performance deteriorates due to increased parasitic resistance
Solution Approach 1:
The invention applies local quality by varying the fairing geometry locally to achieve optimal clearance at different locations. Rather than using a uniform distance offset, the fairing is shaped to maintain appropriate clearance zones where contact risks exist while allowing closer proximity to the fuselage in areas where the elevator cannot reach. This localized optimization minimizes overall parasitic resistance while ensuring contact avoidance critical zones.
Solution Approach 2:
The invention uses preliminary action by pre-defining the virtual envelope that captures all possible elevator positions before designing the fairing. This envelope serves as a preliminary constraint that guides the fairing design process, allowing the designer to optimize the fairing shape within these predetermined boundaries. The envelope is constructed by calculating maximum excursions of the elevator for all combinations of trim angles and elevator deflections, then using this pre-established boundary to shape the fairing for optimal aerodynamic performance.
Data Source
Figure 1
Figure 2a~2c
Figure 3
AI summary
Fairing (9) which closes the internal end of the elevator (3) of an aircraft with respect to the fuselage section (1) on which said fairing (9) moves, with said elevator (3) arranged on a horizontal stabiliser (2) of the aircraft, in such a way that the horizontal stabiliser (2) moves with a trim angle (α) with respect to the fuselage section (1) in turn rotating the elevator (3) with an elevator angle (ß) with respect to the horizontal stabiliser (2), with the fairing (9) maintaining a distance (6) with respect to the fuselage section (1) during its movement in which the aforementioned distance (6) is a minimised distance for all movement ranges of the elevator (3) both for the trim angle trim angle (α) of the horizontal stabiliser (2) and the elevator angle (ß) of the elevator (3), in this way reducing aerodynamic losses through parasitic resistance which is not caused by support of the aircraft. The invention also describes a procedure for obtaining the design of such a fairing (9).