Single-Blade Rotor Layout for Hybrid Aircraft Payload Balance

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Solution Overview

Problem

Existing hybrid aircraft designs face a trade-off between maximizing lift and minimizing counterweight weight, which affects payload capacity, particularly in two-bladed rotor systems with single-bladed wings.

Innovation Solution

The aircraft is designed with two single-bladed rotors where the rotor mast axis divides each blade into two parts, with a ratio of r/R approximately equal to 0.2, optimizing the relationship between blade length, counterweight position, and rotor spacing for improved payload and power efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If blade length is increased to maximize lift, then lift capacity is improved, but counterweight mass must increase which reduces payload

Engineering Contradiction:
ImproveliftVSAvoidcounterweight mass
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The invention optimizes the r/R ratio parameter (distance from rotor axis to counterweight center of gravity divided by blade length) to a specific range of 0.15-0.25. This parameter optimization allows the system to achieve maximum lift while minimizing counterweight mass, resolving the contradiction between lift capacity and payload by finding the optimal geometric configuration rather than simply increasing or decreasing counterweight size.

Inventive Principle:
Principle #35Parameter changes

2Weight of moving object

If counterweight is moved closer to rotor axis to reduce its mass, then dead weight is reduced, but lift capacity decreases

Engineering Contradiction:
Improvedead weightVSAvoidlift
Core Design Contradiction:
Weight of moving objectVSForce

Solution Approach 1:

By defining and optimizing the r/R ratio within the specific range of 0.15-0.25, the invention determines the precise optimal position of the counterweight relative to blade length. This parameter optimization ensures that the counterweight is positioned to generate sufficient centrifugal force for lift while minimizing its mass, thereby reducing dead weight without sacrificing lift capacity.

Inventive Principle:
Principle #35Parameter changes

3Weight of moving object

If r/R ratio is decreased below 0.2, then counterweight mass is reduced, but payload decreases due to excessive dead weight increase

Engineering Contradiction:
Improvecounterweight massVSAvoidpayload
Core Design Contradiction:
Weight of moving objectVSQuantity of substance

Solution Approach 1:

The invention establishes the optimal r/R ratio range of 0.15-0.25 through parameter optimization. Within this range, the system achieves the best balance between counterweight mass and payload capacity. The lower bound of 0.15 prevents the counterweight from being too close to the rotor axis (which would reduce lift), while the upper bound of 0.25 prevents the counterweight from being too far out (which would increase dead weight and reduce payload).

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 configuration enhances payload capacity and power efficiency by balancing lift and counterweight weight, achieving optimal performance within a specific r/R ratio range of 0.15 to 0.25.

Implementation Method 1

a two-successive rotating-wing architecture... the rotor axes are spaced along the vehicle's roll axis... capable of vertical or short takeoff

Methodology Applied
Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 2

the counterweight in the case of a single-bladed propeller is a dead weight... the ratio between blade length and counterweight length is around 20%

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3765363B1Aerial vehicle comprising at least two rotating blades aligned along its roll axis
Publication Date: 2025.12.10 INNOSTAR
  • EP3765363B1 patent drawingFigure 1~3

AI summary

The invention relates to a hybrid aerodyne comprising a fuselage (1), a fixed wing (2, 4) and at least two rotary wings (6, 7), the latter being capable of producing lift by their rotation in the vertical flight phase and of being immobilized and stowed longitudinally in cruising flight phase, and comprising at least one counterweight (6d) mono-blade (6) located at the top of the fuselage (1), each wing comprising a rotor mast (8, 9) which are spaced apart from one another along the roll axis (la) of the aerodyne. The invention is characterized in that the length of the counterweight (6c, 6d) (r) is between 15 and 25 % of the length (R) of the active part (6a, 6b) of the mono-blade (6).