Tail Rotor Gearbox Support Assembly for Helicopters
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Solution Overview
Problem
Existing shrouded tail rotor assemblies for helicopters are heavy, noisy, and inefficient in transferring torque and thrust loads to the airframe, due to reliance on weighty gearbox housings and numerous spokes that increase drag and noise.
Innovation Solution
A tail rotor gearbox support assembly comprising a support column and upper and lower crossbars that couple the tail rotor gearbox to the shroud and tailboom, allowing direct load transfer to stable airframe components while reducing weight and noise through aerodynamic design and pin joint assemblies that accommodate thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tail rotor gearbox housing is used to encase the gearbox and suspend it within the shroud, then the gearbox is protected and supported, but the weight and drag of the helicopter increase
Solution Approach 1:
The patent removes the traditional tail rotor gearbox housing entirely, extracting only the essential support function. The gearbox is suspended directly within the shroud using a stator assembly with spokes, eliminating the redundant housing structure that added weight and drag while providing no additional functional benefit.
Solution Approach 2:
The shroud structure is made multi-functional by having it directly support the gearbox suspension function. The stator assembly integrates the support function into the existing shroud structure, eliminating the need for a separate housing and reducing overall system weight while maintaining gearbox protection through the shroud's inherent structural integrity.
2Reliability
If a stator assembly with several radially emanating spokes is used to encircle and attach the gearbox housing to the shroud, then the gearbox is securely attached, but torque and thrust loads are not transferred efficiently to stable airframe components
Solution Approach 1:
The patent extracts the load transfer function from the stator assembly and relocates it to the tailboom airframe. The stator assembly is redesigned to have fewer spokes that serve only for structural attachment, while the actual torque and thrust loads are directly transferred to the stable tailboom airframe components, improving load transfer efficiency.
Solution Approach 2:
The patent introduces the tailboom airframe as an intermediary structure that mediates the load transfer path. Instead of relying on the stator assembly spokes to transfer loads, the design creates a direct load path through the tailboom airframe, which is a more stable and efficient structure for handling torque and thrust loads.
3Reliability
If a stator assembly with several radially emanating spokes is used to encircle the gearbox, then the gearbox is securely attached, but the amount of noise emitted by the shrouded tail rotor increases
Solution Approach 1:
The patent removes the noise-generating elements by reducing the number of stator assembly spokes to a minimum necessary for structural attachment. This extraction of unnecessary spokes eliminates the aerodynamic noise they generate while maintaining sufficient gearbox attachment stability.
Solution Approach 2:
The patent changes the structural parameter of the stator assembly by reducing the number of spokes. This parameter change directly reduces the aerodynamic interference and noise generation while maintaining the essential attachment function, thereby reducing the harmful noise effect.
Data Source
AI summary
A tail rotor assembly coupled to a tailboom of a helicopter includes a tail rotor gearbox having top, bottom and aft sides and a shroud surrounding the tail rotor gearbox. The shroud includes a shroud airframe having top and bottom portions. The tail rotor assembly includes a tail rotor gearbox support assembly configured to support the tail rotor gearbox within the shroud. The tail rotor gearbox support assembly includes a support column coupling the aft side of the tail rotor gearbox between the top and bottom portions of the shroud airframe, an upper support crossbar coupling the top side of the tail rotor gearbox between the support column and the tailboom airframe and a lower support crossbar coupling the bottom side of the tail rotor gearbox between the support column and the tailboom airframe.