Actuation Apparatus for Thin Wing Control Surfaces

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Solution Overview

Problem

High-speed aircraft with thin swept wings face challenges in actuating control surfaces due to the misalignment of actuators with the airstream, which increases drag and complicates the movement of control surfaces coupled to the trailing edge.

Innovation Solution

An actuation apparatus is designed with actuators aligned with the airflow, utilizing a pivot fitting such as a bell crank to translate force to a drive rod, which is oriented normal to the trailing edge, allowing for a space-efficient design enclosed within a fairing aligned with the airstream, reducing overall drag.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If actuators are positioned to control control surfaces on swept-wing aircraft, then the control surfaces can be actuated, but the actuators become misaligned with the airstream increasing drag

Engineering Contradiction:

Improvecontrol surface actuationVSAvoidaerodynamic drag

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A bell crank pivot fitting acts as an intermediary mechanism between the actuator and the control surface. The actuator remains aligned with the airstream while the bell crank translates its linear motion into the rotational motion needed to actuate the control surface, eliminating the need for misaligned actuators and reducing aerodynamic drag.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the conventional direct mechanical connection between misaligned actuators and control surfaces with a mechanism using a bell crank pivot fitting. This substitution allows the actuator to remain aerodynamically aligned while still achieving control surface actuation through mechanical advantage and motion transformation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If actuators are aligned with the airstream to reduce drag, then aerodynamic performance improves, but the actuation mechanism becomes more complex

Engineering Contradiction:

Improveaerodynamic dragVSAvoidactuation mechanism

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The actuation system is segmented into distinct functional components: the actuator aligned with the airstream, the bell crank pivot fitting for motion transformation, and the control surface linkage. This segmentation allows each component to be optimized for its specific function while maintaining overall system simplicity and aerodynamic efficiency.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If the actuation apparatus is enclosed in a fairing aligned with the airstream, then drag is reduced, but the space available for components is limited

Engineering Contradiction:

Improveaerodynamic dragVSAvoidfairing internal volume

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The bell crank pivot fitting utilizes three-dimensional spatial arrangement to transform linear actuator motion into rotational control surface motion within the constrained fairing volume. By operating in multiple dimensions, the mechanism achieves full control surface actuation capability while maintaining a compact, aerodynamically efficient fairing configuration.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 effectively minimizes drag by aligning the actuation components with the airflow, enabling efficient rotation of control surfaces while maintaining a compact fairing design, thus enhancing the aerodynamic performance of high-speed aircraft.

Implementation Method 1

a pivot fitting pivotally coupled to a lower surface of the swept-wing by a pivot pin, the pivot fitting having an aft portion coupled to a forward end of the drive rod, and an actuator disposed on the lower surface of the swept-wing. The actuator is coupled to the pivot fitting such that an applied force by the actuator in the streamwise direction rotates the pivot fitting such that the applied force is translated to the drive rod to rotate the control surface.

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentUS11851160B2Actuation apparatus for control of thin wing aircraft surfaces

Publication Date: 2023.12.26 THE BOEING CO

AI summary

An actuation apparatus for a control surface rotatably coupled to a swept-wing includes a pivot arm coupled to the control surface and proximate the hinged end of the control surface, a drive rod oriented normal to the trailing edge of the swept-wing, the drive rod having an aft end coupled to the pivot arm, a pivot fitting pivotally coupled to a lower surface of the swept-wing by a pivot pin, the pivot fitting having an aft portion coupled to a forward end of the drive rod, and an actuator disposed on the lower surface of the swept-wing. The actuator is coupled to the pivot fitting such that an applied force by the actuator in the streamwise direction rotates the pivot fitting such that the applied force is translated to the drive rod to rotate the control surface.