Rotorcraft Integral Stabilizer Box Configuration
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Solution Overview
Problem
Existing rotorcraft stabilizer arrangements, such as T-tail and double-decker configurations, are sensitive to gusts and vibrations due to low stiffness and suffer from aerodynamic inefficiencies due to mutual interference between wings in the double-decker configuration.
Innovation Solution
A rotorcraft with a ducted tail rotor and a shroud forming a transverse duct, featuring an integral stabilizer arrangement in a box configuration with high and long upper and low and short lower horizontal stabilizers, connected via an aerodynamically profiled strut, which increases effective span and reduces induced drag, and is positioned to minimize interference with main rotor downwash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a T-tail configuration with a horizontal stabilizer positioned away from the main rotor downwash is used, then the negative influence to trim and handling is avoided and aerodynamic efficiency is improved, but the tail wing becomes sensitive to gusts and vibrations due to low stiffness
Solution Approach 1:
The horizontal stabilizer is divided into multiple segments (first horizontal stabilizer, second horizontal stabilizer, third horizontal stabilizer) arranged at different heights and positions. This segmentation allows each segment to contribute to both aerodynamic efficiency and structural stiffness, resolving the contradiction by distributing the functional requirements across multiple components rather than relying on a single large stabilizer positioned far from the downwash.
Solution Approach 2:
The stabilizer arrangement transitions from a conventional two-dimensional planar configuration to a three-dimensional multi-level structure with stabilizers at different heights (upper, middle, lower positions). This dimensional change enables the system to achieve both high aerodynamic efficiency (by positioning stabilizers in favorable airflow regions) and high stiffness (through the vertical distribution and interconnection of stabilizer segments).
2Stability of the object's composition
If a double-decker configuration with superposed wings is used, then the area influenced by main rotor downwash is reduced and stiffness is slightly higher, but aerodynamic efficiency decreases due to mutual interference between wings
Solution Approach 1:
Each horizontal stabilizer segment is positioned in a specific local region with distinct airflow characteristics. The first horizontal stabilizer is positioned in the upper region, the second in the middle region, and the third in the lower region, allowing each to operate in its own favorable airflow zone and minimize mutual interference while maintaining high overall aerodynamic efficiency.
Solution Approach 2:
The stabilizer configuration uses vertical spacing between segments at different heights to reduce mutual aerodynamic interference, contrasting with the horizontal stacking of double-decker wings. This vertical distribution in three-dimensional space allows each segment to access cleaner airflow while maintaining structural stiffness through the interconnected framework.
3Device complexity
If a conventional stabilizer arrangement is used, then the structure is simpler, but the rotorcraft is more sensitive to gusts and vibrations
Solution Approach 1:
The horizontal stabilizer is segmented into multiple smaller stabilizer units (first, second, and third horizontal stabilizers) positioned at different heights and locations. This segmentation increases the overall structural stiffness and reduces sensitivity to gusts and vibrations while maintaining manageable complexity through modular design and systematic arrangement.
Solution Approach 2:
The stabilizer system functions as a composite structure combining multiple stabilizer segments, vertical stabilizers, and connecting struts into an integrated framework. This composite arrangement achieves high stiffness and vibration resistance through the synergistic combination of multiple components, analogous to how composite materials achieve enhanced properties through material combination.
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 integral stabilizer arrangement enhances aerodynamic efficiency, increases stiffness, and generates additional counter-torque thrust, providing improved stability in yaw and pitch while avoiding downwash interference, thus improving overall rotorcraft stability and performance.
Implementation Method 1
an aerodynamically profiled strut (10), which increases effective span and reduces induced drag
Implementation Method 2
avoiding downwash interference
Data Source
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AI summary
The invention is related to a rotorcraft (1) with at least one main rotor (1a) and a fuselage (2), comprising: a tail boom (2a) connected to the fuselage (2), the tail boom (2a) extending in a longitudinal direction (2c) from the fuselage (2) toward a duct-type portion (7); a shroud (3) provided at the duct-type portion (7) and forming a transverse duct (6) comprising an air inlet region (6b) and an air outlet region (6c); the transverse duct (6) having a longitudinal extension (6a); at least one ducted tail rotor rotatably arranged in the transverse duct (6); and an integral stabilizer arrangement (5, 9, 10) mounted to the shroud (3), the integral stabilizer arrangement (5, 9, 10) being embodied in box configuration and arranged laterally on a side of the shroud (3) on which the air inlet region (6b) of the transverse duct (6) is arranged.