Aircraft Landing Gear Deployment Control for Late Approach Noise Reduction
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Solution Overview
Problem
Aircraft landing gear noise during approach is significant due to high-speed airflow, causing undesirable aero-acoustic noise, especially when landing gear is deployed early in the landing process, affecting densely populated areas near airports.
Innovation Solution
An automatic landing gear deployment controller that deploys the landing gear as late as possible before touchdown, using a pre-computed adjustment routine to maintain aircraft stability and deploy the gear by gravity, with a damping device to reduce impact loads, allowing for precise and reliable deployment and retraction, even if the retraction actuator jams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the landing gear is deployed early in the landing approach, then the landing gear has sufficient time to deploy and lock before touchdown, but the duration and intensity of aero-acoustic noise increases significantly
Solution Approach 1:
The patent replaces manual pilot control with an automated landing gear deployment control system that uses sensors, processors, and actuators to automatically deploy the landing gear at the optimal moment. This substitution enables precise timing control that minimizes noise while ensuring reliable deployment, as the system can execute deployment commands with greater accuracy and consistency than manual operation.
Solution Approach 2:
The patent changes the deployment timing parameter by using real-time calculation of deployment time based on current aircraft conditions and pre-determined deployment parameters. The system dynamically adjusts the deployment moment to occur as late as possible while still ensuring the gear locks before touchdown, thereby minimizing the duration of noise-generating airflow around the gear.
2Object-affected harmful factors
If the landing gear is deployed as late as possible before touchdown, then aero-acoustic noise is reduced, but the risk of insufficient deployment time increases
Solution Approach 1:
The patent applies preliminary action by pre-determining deployment parameters and calculating deployment time in advance based on aircraft conditions. The system pre-calculates the optimal deployment moment and prepares the deployment sequence, ensuring that when deployment is initiated, it proceeds with sufficient time margin to lock before touchdown.
Solution Approach 2:
The patent implements feedback mechanisms through sensors that monitor landing gear position, lock status, and deployment progress in real-time. This feedback allows the control system to verify that deployment is proceeding correctly and to make adjustments if needed, ensuring reliable deployment even when timing is optimized to minimize noise.
3Use of energy by moving object
If the landing gear is deployed later in the landing approach, then fuel consumption is reduced due to cleaner aerodynamic profile, but the aircraft stability may be adversely affected during deployment
Solution Approach 1:
The patent applies preliminary action by pre-computing trim adjustment routines before landing gear deployment. These pre-calculated trim commands are prepared based on expected gear deployment effects, allowing the flight control system to immediately apply stability corrections when the gear is deployed, thereby minimizing disruption to aircraft stability.
Solution Approach 2:
The patent uses the flight control system as an intermediary between the landing gear deployment action and aircraft stability. The flight control system monitors deployment in real-time and applies compensating control inputs to maintain stability, acting as a mediator that isolates the pilot from the destabilizing effects of late gear deployment while still achieving the fuel-saving benefits.
4Productivity
If gravity deployment is used to increase deployment speed, then the landing gear can be deployed later, but the impact loads on the gear structure increase
Solution Approach 1:
The patent applies beforehand cushioning by incorporating damping devices that are pre-positioned to absorb impact loads during gravity deployment. These damping elements are designed to engage at controlled points during the deployment sequence, cushioning the main strut's movement and reducing peak impact forces on the gear structure while still enabling rapid gravity-assisted deployment.
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 the duration and intensity of aero-acoustic noise by deploying the landing gear closer to the airport, maintaining a clean aerodynamic profile and reducing fuel consumption, while ensuring reliable deployment and retraction of the landing gear.
Implementation Method 1
the damping device slows the main strut to reduce impact loads as the strut becomes fully deployed
Implementation Method 2
the retraction linkage permits relative movement between the first joint and the second joint independently of the extension state of the retraction actuator
Data Source
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AI summary
An aircraft assembly (20) comprising: one or more landing gear (210) each arranged to be moved between a stowed condition for flight and a deployed condition for take-off and landing, the landing gear having a known deployment value ; landing gear deployment apparatus (28) for permitting the landing gear to move from the stowed condition to the deployed condition; landing gear down-lock sensing apparatus (30) for detecting that the landing gear has assumed the deployed condition and providing a down-lock signal indicative of the landing gear having assumed the deployed condition; an aircraft navigation system (34) for providing aircraft position relative to a target runway and aircraft speed information; an aircraft landing gear control system (22) for providing a deploy signal to the landing gear deployment apparatus to deploy the landing gear and receiving the down lock signals from the landing gear sensing apparatus; an aircraft flight control system (40); and a landing gear deployment controller (48) communicatively coupled to the aircraft navigation system, the aircraft landing gear control system and the aircraft flight control system. The landing gear deployment controller is configured to: calculate a touch down value using the aircraft position and speed information provided by the aircraft navigation system; command the aircraft landing gear control system to provide the deploy signal when the touch down value reaches a deployment threshold value which is greater than the landing gear deployment value ; and command the aircraft flight control system to execute a landing abort sequence if the controller does not receive the down-lock signal from the landing gear sensing apparatus within a deployment value window which is greater than or equal to the known deployment value for the landing gear but less than the touch down value.