Aircraft Landing Gear Four-Bar Linkage for Compact Wing Stowage
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Solution Overview
Problem
The design of aircraft landing gear is constrained by the need to fit within the wing while maintaining a high aspect ratio and a forward center of gravity, leading to compromises in weight, complexity, cost, ride comfort, and braking performance.
Innovation Solution
An aircraft landing gear with a four-bar linkage and adjustable upper link, allowing the suspension mechanism to adapt to different configurations for stowage and shock absorption, featuring a shock absorber that maintains wheel contact with the ground during takeoff and landing, and a compact design for aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the Oleo strut is swept backwards at a greater angle to position wheels further back, then the center of gravity can be further back, but the shock absorbing properties are affected and ride quality worsens
Solution Approach 1:
The patent applies the dynamics principle by making the Oleo strut angle adjustable rather than fixed. The strut can change its swept angle dynamically - being swept backwards during flight to match the wing shape and allow high aspect ratio wings, then becoming more vertical during landing and takeoff to maintain proper shock absorbing properties and ride quality. This resolves the contradiction by allowing the system to optimize for different operational phases.
2Use of energy by moving object
If the landing gear is designed to fit within narrow wings for high aspect ratio, then aerodynamic efficiency improves, but the landing gear must be narrower and may compromise weight, complexity, cost, ride comfort or braking performance
Solution Approach 1:
The landing gear employs dynamic adjustment of the Oleo strut angle to resolve the contradiction between narrow wing fitment and performance requirements. During cruise, the strut is swept back to allow compact stowage within narrow wings, enabling high aspect ratio wings for fuel efficiency. During landing and takeoff, the strut angle adjusts to provide adequate width and spacing for proper shock absorption and braking performance, avoiding the need for permanently complex landing gear designs.
3Use of energy by moving object
If wings of higher aspect ratio are used for better fuel efficiency, then less space is available for accommodating landing gear, but the center of gravity moves rearwards requiring landing gear further back
Solution Approach 1:
The adjustable Oleo strut angle enables the landing gear to achieve a swept-back configuration that positions the wheels further rearwards on the wing, allowing the use of higher aspect ratio wings for improved fuel efficiency. The dynamic adjustment allows the landing gear to occupy less fore-aft space when swept back, creating room for high aspect ratio wings while maintaining the ability to move wheels rearwards to balance the center of gravity.
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 solution allows for higher aspect ratio wings by positioning the center of gravity further back, improving ride comfort and braking performance while maintaining aerodynamic efficiency and ease of stowage.
Implementation Method 1
the shock absorber is arranged to urge the four-bar linkage away from the shortened position and towards the lengthened position
Data Source
AI summary
An aircraft landing gear has a suspension mechanism which has a four-bar linkage that comprises four links rigidly extending between a corresponding four pivots. A lower link of the four-bar linkage supports front and rear wheels, and is movable relative to an upper link between lengthened and shortened positions. A shock absorber urges the four-bar linkage towards the lengthened position. A length of the upper link of the four-bar linkage is adjustable.