Aircraft Empennage Actuator Segmentation for Fuselage Space
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Solution Overview
Problem
The existing configuration of Trimmable Horizontal Stabilizer Actuators (THSA) in aircraft empennages limits the space available in the pressurized fuselage section for passengers and cargo, and requires maintenance access from within the aircraft, adding weight and complexity.
Innovation Solution
The use of two smaller actuator units instead of a single larger one, positioned further back due to a swept horizontal tail plane configuration, allows for more rearward placement of the Rear Pressure Bulkhead, optimizing space and enabling external maintenance access through side doors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single large actuator is used for the trimmable horizontal stabilizer, then the actuation function is achieved, but the space required in the pressurized fuselage section increases, reducing space for passengers and cargo
Solution Approach 1:
The single large actuator is divided into two separate actuator units (first and second actuator units), each positioned on opposite sides of the fuselage. This segmentation reduces the volume required in the pressurized fuselage section while maintaining the actuation function through coordinated operation of both units.
2Volume of moving object
If the actuator is positioned forward in the fuselage, then the structural support is improved, but the Rear Pressure Bulkhead position is limited, reducing space for passengers and cargo
Solution Approach 1:
The actuator units are positioned laterally on opposite sides of the fuselage rather than being concentrated in a single forward location. This dimensional redistribution allows the Rear Pressure Bulkhead to be positioned more rearward, increasing cargo space while the lateral positioning provides adequate structural support through distributed loading.
3Ease of repair
If maintenance access is provided from inside the fuselage, then the actuator can be maintained, but maintenance platforms are required, adding weight and complexity
Solution Approach 1:
The actuator units are extracted from the internal fuselage environment and positioned on the outer surface of the fuselage. This extraction eliminates the need for maintenance platforms and internal access structures, allowing direct maintenance access from the exterior while reducing overall system weight and complexity.
4Volume of moving object
If a maintenance door is positioned below the actuator, then access is provided, but the actuator position is constrained, limiting space optimization
Solution Approach 1:
Instead of positioning the actuator vertically above a maintenance door (constraining it to a specific location), the actuator units are positioned laterally on the fuselage surface. This dimensional change allows the maintenance doors to be positioned independently for optimal access while the actuators can be located to maximize space utilization.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Aircraft empennage, comprising: - a rear fuselage section (1), - a trimmable horizontal tail plane (2) comprising a first and a second lateral torsion box (21, 22), each comprising a front spar (211, 221) and a rear spar (212, 222), - a front fitting (4) and a rear fitting (5), - an actuator (3) acting on the front fitting (4) for a rotation of the trimmable horizontal tail plane (2) around a hinge axis (11) passing through the rear fitting (5), - the front fitting (4) comprising a first and a second front fitting units (41, 42) being joined to the front spars (211, 221) of the lateral torsion boxes (21, 22), and - the actuator (3) comprising a first and a second actuator units (31, 32), each acting on the first front fitting unit (41) and the second front fitting unit (42) respectively.