Aircraft Braking Bogie Torque Reduction
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Solution Overview
Problem
Aircrafts experience significant torsion loads in the landing gear during tight turning maneuvers, leading to fatigue damage and limitations in on-ground maneuverability, as existing methods like the braked pivot turn generate excessive torque due to differential wheel braking.
Innovation Solution
A method of braked pivot turning that applies a greater braking force to the side of the bogie closer to the aircraft's center of turning than to the side further from it, reducing the net torque on the landing gear by generating a secondary torque in the opposite direction to the primary torque caused by tire scrubbing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a braked pivot turn is performed by applying brakes to all wheels on one landing gear assembly, then the aircraft can turn in a tight circle, but significant torsion loads are generated in the landing gear structure causing fatigue damage
Solution Approach 1:
The patent applies different braking forces to different sides of the bogie. Specifically, it applies a greater braking force to wheels on the first side of the bogie than to wheels on the second side, creating a differential braking effect that reduces the net torque on the landing gear while still enabling the tight turning maneuver
Solution Approach 2:
The patent generates a secondary torque through differential braking that acts in the opposite direction to the primary torque generated by tire scrubbing during the pivot turn. This counter-torque offsets the harmful torsion loads, reducing the net torque and preventing fatigue damage to the landing gear structure
2Ease of operation
If differential engine thrust is applied to turn the aircraft, then the aircraft can maneuver on the ground, but torsion loads are generated in the landing gear due to wheel scrubbing
Solution Approach 1:
The patent applies differential braking forces to different sides of the bogie to create a secondary torque that counteracts the primary torque from tire scrubbing, thereby reducing the net torsion loads on the landing gear while maintaining ground maneuverability
Solution Approach 2:
The patent converts the harmful effect of differential braking (which could increase torque) into a beneficial counter-torque by strategically applying greater braking force to the first side of the bogie, thereby reducing the net torsion loads on the landing gear structure
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
This approach significantly reduces torsion loads in the landing gear, allowing aircrafts to perform tight turns with less fatigue damage and increased maneuverability, enabling larger aircrafts to execute braked pivot turns that were previously restricted.
Implementation Method 1
braking at least one wheel on the landing gear assembly that is located closer to the centre of turning of the aircraft
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 2a~2c
AI summary
A method of braked pivot turning an aircraft (1) , the aircraft (1) comprising a fuselage (3) and a landing gear assembly (9, 10) located to one side thereof. The landing gear comprises a bogie (17) with wheels (19, 20) mounted thereon, at least one wheel being located on a first side of the bogie (17) and at least one wheel being located on a second side of the bogie (17) . The method includes the steps of applying thrust (7'') for moving or turning the aircraft, and via the braking of at least one wheel, applying a greater braking force to the first side of the bogie (17) than to the second side. The first side is located closer to the centre of turning (13) of the aircraft than the second side. The method thereby generates relatively low torque loads in the landing gear leg, reducing fatigue damage. A brake control system is also provided for selectively braking wheels during a turn.