Multi-blade Rotor System for VTOL Aircraft

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Solution Overview

Problem

VTOL aircraft with fixed pitch rotor systems are inefficient in both hover and forward flight operations due to the need for single pairs of rotor blades optimized for only one phase of flight, leading to increased complexity, cost, and weight.

Innovation Solution

A multi-blade rotor system with at least two pairs of rotor blades, each with a different pitch and diameter, where one pair is optimized for hover operations and the other for forward flight, allowing for improved performance across both phases of flight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single pair of rotor blades with fixed pitch is used, then the structure is simple, but the aircraft is inefficient in both hover and forward flight operations

Engineering Contradiction:

Improverotor system structureVSAvoidflight efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The rotor system is segmented into multiple pairs of rotor blades (at least two pairs), each pair having different pitch and diameter characteristics. This segmentation allows each blade pair to be optimized for specific flight phases, resolving the contradiction between structural simplicity and flight efficiency by dividing the rotor system into specialized components rather than using a single universal pair.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different pairs of rotor blades are assigned different local qualities (pitch and diameter) to optimize performance for specific operations. The first pair has pitch and diameter optimized for hover operations, while the second pair has different pitch and diameter optimized for forward flight. This local differentiation resolves the contradiction by allowing each component to have specialized properties rather than requiring a complex adjustable system.

Inventive Principle:

Principle #3Local quality

2Productivity

If adjustable pitch rotor blades are used to optimize both hover and forward flight, then flight performance improves, but system complexity and cost increase

Engineering Contradiction:

Improveflight performanceVSAvoidpitch adjustment mechanism

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Instead of using a single adjustable pitch mechanism for all rotor blades, the system segments the rotor blades into multiple fixed-pitch pairs, each optimized for different flight phases. This eliminates the need for complex pitch adjustment mechanisms while maintaining optimized performance across different flight conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Rather than making a single rotor blade pair adjustable to handle different flight conditions, the invention inverts the approach by making multiple rotor blade pairs fixed with different characteristics. This eliminates the need for adjustment mechanisms while achieving the same performance optimization goal.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If multiple rotor blade pairs with different pitch and diameter are used, then performance in both hover and forward flight improves, but device complexity increases

Engineering Contradiction:

Improveperformance across flight phasesVSAvoidnumber of rotor blade pairs

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The multi-pair rotor blade system provides universal functionality by enabling the aircraft to efficiently perform both hover and forward flight operations with fixed-pitch blades. Each pair serves a specific function (hover optimization or forward flight optimization), and together they provide multi-functional capability without requiring complex adjustment mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 multi-blade rotor system enhances flight performance by providing effective vertical thrust for hovering and forward thrust for forward flight, reducing complexity, cost, and weight compared to adjustable pitch systems.

Implementation Method 1

a first pair of rotor blades comprising a first pitch and a first diameter; and a second pair of rotor blades comprising a second pitch and a second diameter

Methodology Applied

Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 2

one pair is optimized for hover operations and the other for forward flight, allowing for improved performance across both phases of flight

Methodology Applied

Scientific EffectAerodynamic thrust: Aerofoil

Data Source

PatentEP3683141B1Multi-blade rotor system

Publication Date: 2021.06.30 BELL HELICOPTER TEXTRON INC

Figure 1A
Figure 1B
Figure 2A

AI summary

A rotor system (200, 300, 400, 500) is provided in one example embodiment and may include a first pair of rotor blades (210, 310, 410, 510) comprising a first pitch (P1) and a first diameter (D1); and a second pair of rotor blades (220, 320, 420, 520) comprising a second pitch (P2) and a second diameter (D2) wherein the first pitch (P1) of the first pair of rotor blades (210, 310, 410, 510) and the second pitch (P2) of the second pair of rotor blades (220, 320, 420, 520)are different.