Propeller Blade Control for Constant Torque

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Solution Overview

Problem

Turboprop aircraft without propeller fairing experience significant normal stresses (loads 1P) that affect controllability, stability, and performance, requiring increased stabilization and control surfaces, which increase drag and mass, and do not contribute to the aircraft's mission.

Innovation Solution

The method involves determining a constant reference control torsion moment for each propeller blade and automatically adjusting its setting angle to maintain a constant torsion aerodynamic moment, reducing structural fatigue and energy dissipation, and allowing for reduced stabilization and control surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the aircraft structure is sized to withstand high loads 1P, then structural strength is improved, but aircraft mass increases

Engineering Contradiction:

Improvestructural strengthVSAvoidaircraft mass

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent converts the harmful alternating loads 1P into beneficial constant loads by adjusting propeller blade settings. The loads 1P, which normally cause structural stress and require heavier aircraft design, are transformed into a constant magnitude that can be structurally optimized, thereby reducing aircraft mass while maintaining strength

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the parameter of load magnitude from variable to constant by adjusting blade setting angles. This parameter transformation allows the structure to be designed for constant rather than peak variable loads, reducing the required structural mass

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If stabilization and control surfaces are increased to counteract loads 1P, then aircraft stability is improved, but drag increases

Engineering Contradiction:

Improveaircraft stabilityVSAvoiddrag

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent converts the destabilizing alternating loads 1P into stabilizing constant loads. By adjusting blade settings, the previously harmful variable loads become beneficial constant loads that reduce the need for additional stabilization surfaces, thereby reducing drag

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Power

If propeller blades are subjected to alternating loads 1P, then thrust generation is maintained, but structural fatigue increases

Engineering Contradiction:

Improvethrust generationVSAvoidstructural fatigue

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent converts the harmful alternating loads into beneficial constant loads on propeller blades. The blade setting angles are adjusted so that while thrust generation is maintained, the alternating load pattern is transformed into a constant load pattern, eliminating fatigue

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the temporal parameter of the load from alternating to constant by dynamically adjusting blade settings during rotation. This parameter change eliminates the fatigue-causing alternation while preserving the thrust-generating capability

Inventive Principle:

Principle #35Parameter changes

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 decreases or eliminates loads 1P, improving propulsive efficiency, reducing the aircraft's mass, and minimizing sound signature, while enabling adjustable thrust during flight.

Implementation Method 1

each one of said blades being submitted to one torsion aerodynamic moment

Methodology Applied

Scientific EffectAerodynamic lift and drag: Aerofoil

Implementation Method 2

when the air flow upstream the propeller of turboprops has a not nil incidence with respect to the rotation axis of the propeller

Methodology Applied

Scientific EffectAerodynamic incidence: Aerofoil

Implementation Method 3

each one of said blades being submitted to one torsion aerodynamic moment

Methodology Applied

Scientific EffectTorsion moment: Torque

Data Source

PatentUS8647062B2Method and device for improving performances of an aircraft comprising at least one propeller engine without propeller fairing

Publication Date: 2014.02.11 AIRBUS OPERATIONS (SAS)

AI summary

A device for improving performance of an aircraft with a propeller includes a constant torque blade setting device that slaves, automatically and independently, blade setting angles, respectively associated with blades of the propeller, to a constant reference control moment predetermined, for a desired propeller thrust value. The blade setting angles are intended to be applied on each blade such that torsion aerodynamic moments applied on blades stay roughly equal to the reference control moment regardless of the angular position of blades in the propeller plane. A corresponding method for improving performance of an aircraft includes the use of the constant torque blade setting device to slave blade setting angles to a constant reference control moment.