Three-Position Aircraft Tail Skid Mechanism
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Solution Overview
Problem
Existing aircraft tail skid mechanisms that utilize the same position for takeoff and landing restrict downward rotation, leading to higher takeoff speeds and longer runway requirements, and lack the ability to be selectively deployed to minimize component count and size.
Innovation Solution
A three-position aircraft tail skid mechanism with a ground contact shoe that can be moved between a stow, landing, and takeoff position, utilizing a combination of actuators and over-center locking mechanisms to optimize tail skid deployment and prevent tail strike damage, while minimizing the number and size of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a tail skid mechanism uses the same position for both takeoff and landing, then the device complexity is reduced, but the aircraft requires higher rotation speeds and longer runways for takeoff
Solution Approach 1:
The tail skid mechanism employs dynamic positioning capability, allowing the skid to be selectively deployed to different positions (takeoff position and landing position) based on the operational phase. This dynamic adjustment enables the mechanism to optimize aircraft rotation speed during takeoff while providing adequate protection during landing, resolving the contradiction between device simplicity and performance optimization
Solution Approach 2:
The invention changes the positional parameter of the tail skid between takeoff and landing operations. By deploying the skid to a first position for takeoff (allowing greater downward rotation) and a second position for landing (providing protection at lower speeds), the system optimizes takeoff rotation speed and runway requirements without significantly increasing mechanism complexity
2Manufacturing precision
If a tail skid mechanism provides fixed position for takeoff and landing, then the manufacturing precision requirements are reduced, but the aircraft performance during takeoff is degraded
Solution Approach 1:
The mechanism transitions from fixed positioning to dynamic selective positioning, where the tail skid can be deployed to optimized positions for different operational phases. This enables precise control over tail rotation limits during takeoff versus landing, improving takeoff efficiency without requiring excessively tight manufacturing tolerances on the mechanism itself
3Adaptability or versatility
If a tail skid mechanism is designed with three-position capability, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The tail skid mechanism is designed with multi-functionality, where a single mechanism structure performs multiple functions: providing protection during landing, enabling optimized takeoff performance, and potentially serving as a structural component of the aircraft fuselage. This universal design approach achieves three-position adaptability without proportionally increasing overall device complexity
Solution Approach 2:
The invention merges the tail skid protection function with the aircraft fuselage structure itself, where the fuselage portion serves dual purposes as both structural element and protective skid surface. This integration reduces the need for separate complex mechanism components while maintaining three-position capability
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A system includes an aircraft having a fuselage with a tail portion. A tail skid is disposed in an opening of the tail portion. The tail skid includes a ground contact shoe and a mechanism configured to selectably move the ground contact shoe between respective ones of a stow position disposed within the opening, a landing position disposed below the opening, and a takeoff position different than the stow and landing positions. Before a takeoff or a landing, the ground contact shoe is moved to a corresponding one of the takeoff or landing positions. In the event of an over-rotation or an over-flaring of the aircraft during a takeoff or a landing, respectively, the ground contact shoe makes contact with the ground and a shock absorber of the system absorbs a shock of the contact and thereby prevents tail strike damage to the aircraft.