Laminar Flow Control Door Actuation via Fuselage Linkage

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Solution Overview

Problem

Existing laminar flow control systems for aircraft are complex and costly due to the need for multiple servos in the fin, requiring extensive maintenance and assembly, and they often suffer from turbulence and corrosion issues in the perforated inlets.

Innovation Solution

A laminar flow control system with door assemblies actuated from within the fuselage using a single actuator and linkage, featuring a perforated leading edge and optional nano-coating for corrosion resistance, which reduces turbulence and maintenance needs by eliminating the need for multiple servos and improving accessibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple servos are installed in the fin for laminar flow control, then the system can achieve flow control functionality, but the device complexity and maintenance requirements increase significantly

Engineering Contradiction:
Improvelaminar flow control functionalityVSAvoidnumber of servos and assembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The actuator is extracted from the fin and relocated to the fuselage. A single actuator in the fuselage operates door assemblies in the fin through linkages, eliminating the need for multiple servos embedded in the fin structure. This reduces assembly complexity and maintenance requirements while preserving laminar flow control functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Linkages serve as intermediaries connecting the actuator in the fuselage to the door assemblies in the fin. This mediator mechanism transmits actuation force over distance, allowing centralized control from the fuselage while maintaining functionality at the fin location.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple servos are installed in the fin, then flow control is achieved, but maintenance accessibility and serviceability deteriorate

Engineering Contradiction:
Improveflow control operationVSAvoidmaintenance accessibility
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The actuator is extracted from the difficult-to-access fin location and relocated to the fuselage, which provides excellent maintenance accessibility. Standard door assembly serviceability is achieved while flow control functionality is maintained through the linkage system.

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If perforated inlets are used for laminar flow control, then flow management is improved, but turbulence and corrosion issues arise

Engineering Contradiction:
Improveflow management efficiencyVSAvoidturbulence and corrosion
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

A nano-coating is applied specifically to the perforated inlet surfaces to provide localized corrosion resistance. This targeted treatment protects the vulnerable perforated areas without affecting the overall flow management functionality, reducing both turbulence and corrosion issues.

Inventive Principle:
Principle #3Local quality

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 design simplifies maintenance, reduces weight and complexity, enhances turbulence reduction, and improves fuel economy by lowering the drag coefficient, while also allowing for better placement of high-frequency equipment within the fuselage for improved performance and accessibility.

Implementation Method 1

the linkage to operate the first door in a first open mode in which the first opening faces in a first direction to create a suction airflow path between the perforated surface and the first opening

Methodology Applied
Scientific EffectSuction airflow: Suction

Implementation Method 2

the linkage to operate the second door in a second open mode in which the second opening faces in a second direction to create a purge airflow path between the second opening and the perforated surface

Methodology Applied
Scientific EffectPurge airflow: Convection

Data Source

PatentEP2853485B1Apparatus and methods to operate laminar flow control doors
Publication Date: 2019.03.20 THE BOEING CO
  • EP2853485B1 patent drawingFigure 1
  • EP2853485B1 patent drawingFigure 2
  • EP2853485B1 patent drawingFigure 3

AI summary

Apparatus and methods to operate laminar flow control system doors with improved reliability and serviceability are described herein. One described example apparatus includes a fin (314) of an aircraft, a door assembly (404) on a first side of the fin having a first door (419) defining a first opening and second door (426) defining a second opening. The example apparatus also includes a perforated surface proximate a leading edge of the fin and an actuator (412) disposed in the aircraft. The actuator drives a linkage (402) that couples the door to the actuator. The linkage is to operate the door in a first open mode in which the first opening faces in a first direction to create a suction airflow path between the perforated surface and the first opening, and a second open mode in which the second opening faces in a second direction to create a purge airflow path between the second opening and the perforated surface.