Aircraft Landing Gear Cable-Actuated Energy Absorption
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Solution Overview
Problem
Traditional rotorcraft landing gear systems, such as skid and wheel systems, face challenges including weight penalties, high stress loads, operational inefficiencies, and the inability to maintain a symmetric roll attitude during hard landings, which can lead to hazardous conditions.
Innovation Solution
An energy absorbing landing system with rotatably coupled landing legs and an energy absorption unit that uses cables and mechanical resistors to selectively apply resistance based on landing load magnitude, allowing for dynamic absorption of landing loads and enabling symmetric roll attitude during hard landings, while also being retractable to reduce drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional skid landing gear systems use large and stiff cross tubes to withstand hard landings, then impact resistance is improved, but weight increases
Solution Approach 1:
The landing gear system transitions from a static stiff structure to a dynamic system that can change its mechanical properties during landing. The energy absorption unit provides progressive resistance through cable deformation and mechanical resistor engagement, allowing the structure to be lighter while maintaining impact resistance through controlled deformation rather than rigid stiffness
Solution Approach 2:
The system changes its mechanical resistance parameters during the landing event. The energy absorption unit engages progressively with the landing load, transitioning from low resistance during normal operation to high resistance during hard landings. This parameter change allows the use of lighter components that only need to be strong when needed, rather than continuously strong
2Strength
If traditional skid landing gear systems induce high stress loads on the fuselage, then structural strength requirements are improved, but weight increases
Solution Approach 1:
The energy absorption unit acts as an intermediary between the landing gear and the fuselage. It absorbs and dissipates the impact energy through controlled deformation of cables and mechanical resistors, preventing high stress loads from being transmitted to the fuselage. This allows the fuselage to be designed with lower strength requirements, reducing weight
3Strength
If skid landing gear systems are designed with fixed geometry to maintain structural stiffness, then impact absorption is improved, but retractability is worsened
Solution Approach 1:
The system uses dynamic cable-based connections that allow the landing gear to be deployed and retracted. The cables provide the necessary structural stiffness when deployed through tension, but allow easy retraction when not needed. This dynamic connection method enables retractability without requiring complex mechanical linkages, resolving the conflict between stiffness and retractability
4Productivity
If wheel landing gear systems use complex mechanisms to achieve retractability, then operational efficiency is improved, but device complexity and weight increase
Solution Approach 1:
The invention extracts the complex mechanical retraction mechanism from the landing gear system and replaces it with a simpler cable-based system. The landing gear can be retracted by simply releasing or reconfiguring the cable connections, eliminating the need for complex actuators, linkages, and control systems while maintaining operational efficiency
Solution Approach 2:
The cable-based system allows the landing gear to be self-contained and easily deployable/retractable without requiring complex external mechanisms. The cables themselves provide the structural function, and their configuration can be simply changed to deploy or retract the gear, making the system self-sufficient and low-complexity
5Device complexity
If traditional landing gear systems cannot maintain symmetric roll attitude during hard landings, then structural simplicity is improved, but safety deteriorates
Solution Approach 1:
The energy absorption unit is designed with asymmetric cable routing and mechanical resistor configuration that provides differential resistance to left and right landing legs. This asymmetric design ensures that during hard landings, the system actively works to maintain symmetric roll attitude by providing corrective resistance to prevent asymmetric loading, thereby improving safety while keeping the overall structure relatively simple
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 system effectively absorbs landing loads, reduces stress on the fuselage, maintains a symmetric roll attitude during hard landings, and allows for retractable landing gear, enhancing operational efficiency and safety by minimizing weight and drag.
Implementation Method 1
Traditional helicopter skid landing gear systems rely on plastic deformation of the cross tubes to reduce impact during hard landings
Implementation Method 2
an energy absorption unit configured to absorb the landing load experienced by the aircraft during landing
Implementation Method 3
the energy absorption unit may include a spring to apply the first resistance
Implementation Method 4
the revolute joints may each include a torsion spring to outwardly bias the landing legs
Implementation Method 5
the cable router subsystems may each include at least one pulley assembly
Data Source
AI summary
An energy absorbing landing system for an aircraft having a fuselage includes landing legs rotatably coupled to the fuselage configured to outwardly rotate when receiving a landing load having a magnitude. The energy absorbing landing system also includes an energy absorption unit coupled to the fuselage and cables coupling the energy absorption unit to the landing legs. The energy absorption unit is configured to selectively apply a resistance to the outward rotation of the landing legs via the cables based on the magnitude of the landing load, thereby absorbing the landing load when the aircraft lands.