Rotary Wing Tail Boom Section Optimization
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Solution Overview
Problem
Rotary wing aircraft face challenges in optimizing tail boom sections to minimize detrimental aerodynamic forces such as downforce and maximize beneficial lateral force during hovering and low-speed flight phases, which affects mechanical power distribution and aircraft performance.
Innovation Solution
A method for optimizing tail boom sections using a database of standard sections defined by chord, thickness, and characteristic points, allowing for symmetrical or asymmetrical designs that maximize lateral force or minimize downforce, while ensuring structural integrity and aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the tail boom section geometry is optimized to maximize lateral force, then the mechanical power requirement for anti-torque devices is reduced, but the structural integrity and relative thickness constraints may be compromised
Solution Approach 1:
The patent applies local quality by optimizing specific sections of the tail boom independently. Each section's geometry (chord, thickness, characteristic points) is tailored to local aerodynamic requirements while maintaining overall structural integrity. The method allows different sections to have different aerodynamic properties (maximizing lateral force or minimizing downforce) based on their position and functional requirements.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying geometric parameters (chord length, thickness, characteristic point coordinates) of tail boom sections to optimize aerodynamic performance. The optimization method evaluates multiple parameter combinations to find configurations that maximize lateral force while maintaining structural constraints, directly addressing the contradiction between power reduction and strength preservation.
2Use of energy by moving object
If the tail boom section geometry is modified to minimize downforce, then the power availability for the main rotor is improved, but the aerodynamic efficiency and structural design complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the tail boom into multiple discrete sections, each with independently optimized geometry. This allows the downforce minimization to be applied selectively to specific sections rather than the entire tail boom, reducing overall design complexity while achieving the desired aerodynamic effect. The method evaluates each section's contribution to downforce and optimizes accordingly.
Solution Approach 2:
The patent incorporates dynamics by making the tail boom section geometry adaptable to different flight conditions. The optimization method can adjust section characteristics (chord, thickness, characteristic points) to minimize downforce during hovering and low-speed flight phases when the aircraft is most sensitive to downforce effects, while maintaining structural integrity across all operating conditions.
3Ease of manufacture
If symmetrical sections are used for the tail boom, then the manufacturing ease is improved, but the ability to maximize lateral force or minimize downforce is reduced
Solution Approach 1:
The patent applies asymmetry by allowing tail boom sections to have asymmetric geometries when aerodynamic optimization requires it. The optimization method evaluates whether symmetric or asymmetric configurations better achieve the desired aerodynamic performance (maximizing lateral force or minimizing downforce). Asymmetric sections are implemented where they provide significant aerodynamic benefit, while symmetric sections are used where manufacturing simplicity is prioritized, creating a balanced compromise.
4Strength
If the relative thickness of tail boom sections is increased, then the structural strength is improved, but the aerodynamic drag and downforce increase
Solution Approach 1:
The patent applies local quality by allowing different sections of the tail boom to have different relative thicknesses optimized for their specific functions. Sections where structural strength is critical maintain higher relative thickness, while sections where aerodynamic performance is prioritized have reduced relative thickness. The optimization method evaluates the trade-off between strength requirements and aerodynamic drag/downforce for each section independently.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the relative thickness parameter across different tail boom sections. The optimization method evaluates how changes in relative thickness affect both structural strength and aerodynamic performance, finding optimal values that balance these competing requirements. This allows precise control over the strength-drag/downforce trade-off for each section.
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
This approach reduces the mechanical power requirement for anti-torque devices, enhances power availability for the main rotor, and improves aircraft performance by optimizing aerodynamic forces, thereby improving payload and climb speed.
Implementation Method 1
the air flow from the main rotor sweeps the tail boom from the leading edge to the trailing edge
Implementation Method 2
downforce and lateral force generated by the air flow from the main rotor circulating on the tail boom
Data Source
Figure 1~2
Figure 3~5
AI summary
The present invention relates to a method for optimizing the cross-sections of a tail boom (10) intended for a rotary-wing aircraft, as well as a tail boom (10) comprising such cross-sections. The method comprises a step of creating a database characterizing standard cross-sections of a tail boom (10) favoring the reduction of downforce FD and/or the increase of lateral force FL generated by the airflow of a main rotor of said aircraft circulating over said tail boom (10), a step of establishing desired aerodynamic and structural characteristics of said tail boom (10), and a step of defining said cross-sections of said tail boom (10) as a function of said standard cross-sections and said desired aerodynamic and structural characteristics.The tail beam (10) thus defined optimizes the reduction of downforce FD and/or the increase of lateral force FL generated by said airflow of said main rotor.