Selective Wheel Braking for Aircraft Pivoting Main Landing Gear
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Solution Overview
Problem
Existing systems for braking pivoting main landing gear during aircraft pivot turns result in excessive wheel and tire wear, increased structural loads, and require heavy, bulky components to withstand high loads, lacking methods to selectively brake or allow wheels to roll freely.
Innovation Solution
A brake control system that selectively inhibits braking on certain wheels of the pivoting main landing gear during pivot turns, using a brake control system with a brake inhibit subsystem to manage brake application based on aircraft conditions, reducing structural loads and allowing some wheels to roll freely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all wheels on the pivoting main landing gear are braked during a pivot turn maneuver, then the aircraft can be effectively decelerated and controlled, but excessive wear occurs on the wheels and tires, and increased structural loads are imposed on the pivoting main landing gear
Solution Approach 1:
The braking system is segmented to apply brakes selectively on only some wheels (specifically, wheels on the side of the pivoting gear toward the outside of the turn) while allowing other wheels to roll freely. This segmentation resolves the contradiction by maintaining sufficient deceleration control through partial braking while significantly reducing wear on all wheels and tires.
2Reliability
If all wheels on the pivoting main landing gear are braked during a pivot turn maneuver, then deceleration is achieved, but very high structural loads are imposed on the pivoting main landing gear
Solution Approach 1:
The braking force is segmented and applied only to wheels on the outside of the turn rather than all wheels. This reduces the cumulative structural loads on the pivoting main landing gear while maintaining effective deceleration capability through the braked wheels.
Solution Approach 2:
Instead of applying brakes to all wheels (excessive action), the system applies brakes to only the necessary subset of wheels (partial action) - specifically those on the outside of the turn - which is sufficient to achieve deceleration while minimizing structural loads.
3Strength
If heavy and bulky main landing gear assemblies are used, then the structure can withstand high structural loads and braking loads during pivot turn maneuvers, but the weight of the landing gear increases
Solution Approach 1:
The patent applies partial braking action on only some wheels rather than all wheels, which reduces the peak braking loads that the landing gear structure must withstand. This allows for lighter, less bulky landing gear assemblies while still maintaining sufficient strength to handle the reduced but still significant braking loads during pivot turns.
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
Reduces structural loads and wear on the main landing gear, decreases component weight, and optimizes U-turn maneuvers by allowing selective wheel braking, thereby extending wheel and tire life and reducing the overall weight of the landing gear.
Implementation Method 1
The wheel brakes on the main landing gear are controlled by the pilot after landing to assist in the ground deceleration of the aircraft. The wheel brakes can also be controlled by the pilot during ground taxi maneuvers, and pivot turn maneuvers or 2-point turn maneuvers performed on the ground.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
There is provided a pivot turn load alleviation (PTLA) brake system (12) for alleviating structural loads (28A) on a pivoting main landing gear (32) of an aircraft (10, 316, 96) in a pivot turn maneuver (30A, 30). The PTLA brake system (12) includes a brake control system (14) operatively coupled to at least two main landing gear (24), each having two or more wheels (46). The PTLA brake system (12) further includes a PTLA brake inhibit subsystem (16) coupled to the brake control system (14). The subsystem inhibits braking of one or more of the two or more wheels (46) of the pivoting main landing gear (32), in the pivot turn maneuver (30A, 30), so that at least one wheel (46) of the two or more wheels (46) is in an unbraked state (52), and a remaining number of the two or more wheels (46) are in a braked state (56). The PTLA brake system (12) alleviates structural loads (28A), and reduces wear (136) on the at least one wheel (46) that is in the unbraked state (52).