Circular-Wing Rotorcraft Using Coanda Lift With Smaller Rotors

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Solution Overview

Problem

Existing rotorcrafts, such as multicopters and flying cars, face challenges in reducing size and weight while maintaining efficient lift generation and stability, leading to increased power consumption, structural constraints, and reduced flight range.

Innovation Solution

Incorporating circular wings that utilize the Coanda effect in conjunction with rotors for lift generation, distributing lift loads, and optimizing rotor and wing configurations to minimize weight and structural stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If rotor size is reduced to decrease weight, then weight is reduced, but lift generation capability deteriorates

Engineering Contradiction:
Improverotorcraft weightVSAvoidlift generation capability
Core Design Contradiction:
Weight of moving objectVSForce

Solution Approach 1:

The patent combines the rotor system and circular wing into an integrated lift generation system. The rotor blades are positioned to work in conjunction with the circular wing, where the rotor downwash interacts with the wing surface to generate additional lift through the Coanda effect, allowing smaller rotors to achieve the same total lift capability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The circular wing acts as an intermediary element between the rotor and the air. It captures the rotor downwash and redirects it through the Coanda effect to generate additional lift, effectively amplifying the lift generation capability of smaller rotors and resolving the contradiction between reduced rotor size and maintained lift capability

Inventive Principle:
Principle #24Intermediary (Mediator)

2Force

If circular wings are added to generate lift, then lift generation is improved, but device complexity increases

Engineering Contradiction:
Improvelift generationVSAvoidstructure complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The circular wing structure serves multiple functions simultaneously: it generates lift through the Coanda effect, provides a mounting surface for the rotor system, and creates a streamlined aerodynamic shape. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while maintaining improved lift generation

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Weight of moving object

If rotor size is reduced, then weight is reduced, but power consumption increases

Engineering Contradiction:
Improverotorcraft weightVSAvoidpower consumption
Core Design Contradiction:
Weight of moving objectVSUse of energy by moving object

Solution Approach 1:

By merging the rotor and circular wing into a cooperative lift generation system, the patent achieves more efficient aerodynamic interaction. The circular wing's Coanda effect amplifies the lift from smaller rotors, reducing the total power required compared to conventional systems that would need larger, more powerful rotors to compensate for the reduced rotor size

Inventive Principle:
Principle #5Merging (Combining)

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 integration of circular wings with rotors reduces weight, extends flight range, improves safety and quietness, and enhances stability by distributing lift loads and reducing structural stress, while allowing for efficient use of space for additional components like batteries and wheels.

Implementation Method 1

circular wings that utilize the Coanda effect for lift generation

Methodology Applied
Scientific EffectCoanda effect: Coanda Effect

Data Source

PatentEP4368503B1rotorcraft
Publication Date: 2026.01.21 SUBARU CORP
  • EP4368503B1 patent drawingFigure 1~2
  • EP4368503B1 patent drawingFigure 3
  • EP4368503B1 patent drawingFigure 4~5

AI summary

A rotorcraft (1) includes a fuselage (2), rotors (3) and circular wings (14). The rotors (3) are attached to the fuselage (2). The rotors (3) are attached to the fuselage (2). The circular wings (14) are disposed under the rotors (3) respectively. Upper surfaces of the circular wings (14) have annular curved surfaces and thereby are convex upward respectively. The circular wings (14) cause Coanda effects by the upper surfaces respectively. First lift is generated by rotating the rotors (3). Second lift is generated by the Coanda effects by the circular wings (14). Third lift is generated by air jets deflected downward along the upper surfaces of the circular wings (14) respectively.