Extendable Tailwheel Strut and Ventral Fin for Helicopter Landing Gear
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Solution Overview
Problem
Conventional helicopter tailwheel landing gear configurations often compromise between ground clearance and aerodynamic performance, with existing designs either risking damage from tail rotor contact with the ground or increasing drag during flight.
Innovation Solution
A tailwheel assembly with a ventral fin and extendable strut that secures a tailwheel, allowing for rotation and adjustable extension/retraction via hydraulic pressure, ensuring ground clearance during landing and reducing drag during flight by retracting the strut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tailwheel strut is extended to provide ground clearance for the tail rotor, then ground operation safety is improved, but aerodynamic drag increases during flight
Solution Approach 1:
The tailwheel strut is designed with extendable and retractable portions that can dynamically change length. During ground operations, the strut extends to provide adequate clearance between the tail rotor and ground. During flight, the strut retracts to minimize aerodynamic drag and improve fuel efficiency. This dynamic adjustment resolves the contradiction by adapting the strut length to operational requirements.
Solution Approach 2:
The physical parameter of strut length is changed based on operational mode. The extendable portion of the strut allows the overall length to be increased for ground operations and decreased for flight operations. This parameter change enables the system to optimize both ground clearance and aerodynamic performance at different times.
2Strength
If the ventral fin is fixed to maintain structural stability, then structural strength is improved, but aerodynamic performance during flight deteriorates due to increased drag
Solution Approach 1:
The ventral fin is segmented into a fixed airframe portion and a moveable tailwheel portion. The fixed portion maintains structural strength and proper aerodynamic positioning, while the moveable portion can be retracted along with the tailwheel strut during flight to reduce drag. This segmentation allows the fin to maintain both structural integrity and aerodynamic efficiency.
Solution Approach 2:
The moveable tailwheel portion of the ventral fin is combined with the extendable tailwheel strut assembly. When the strut retracts, the fin portion moves with it, allowing the entire tailwheel assembly and associated fin section to be pulled back into a more aerodynamic position during flight while remaining structurally integrated with the fixed airframe portion.
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
Enhances ground operation safety and aerodynamic performance by maintaining tail rotor clearance and reducing airflow turbulence, while allowing for steering and adjustable extension for varying ground conditions.
Implementation Method 1
allowing for rotation and adjustable extension/retraction via hydraulic pressure
Implementation Method 2
The tailwheel assembly further comprises one or more strut joints in the tailwheel strut to allow for rotation of the tailwheel
Data Source
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AI summary
A tailwheel assembly (22) for an aircraft includes a ventral fin (20) including a fixed airframe portion (36) of the ventral fin and a moveable tailwheel portion (38) of the ventral fin. A tailwheel strut (28) extends through the ventral fin and includes a fixed first strut portion (44) and an extendable second strut portion (42) having the moveable tailwheel portion (38) of the ventral fin secured thereto. A tailwheel (24) is secured to the extendable second strut portion. A method of operating a tailwheel assembly for an aircraft includes extending an extendable portion of a tailwheel strut from an airframe of the aircraft. The tailwheel strut has a tailwheel secured thereto and is located at least partially in a ventral fin of the aircraft. A tailwheel portion of the ventral fin is moved away from a fixed airframe portion of the ventral fin via extension of the extendable portion of the tailwheel strut.