Convertible Aircraft Rotor Layout for Hover-to-Cruise Stability

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Solution Overview

Problem

There is a need for a convertible aircraft that exceeds the limitations of conventional aircraft in terms of stability and aerodynamic drag, while maintaining maneuverability and flexibility for sports competitions and personal air mobility applications.

Innovation Solution

A convertible aircraft design featuring a fuselage with cantilevered half-wings and a tail portion, equipped with rotors that can switch between vertical and horizontal configurations, and a control system to manage thrust and stability, utilizing electric power sources and aerodynamic surfaces for lift and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional aeroplanes use fixed wings for high cruising speeds and high altitudes, then cruising speed and altitude are improved, but the ability to hover and maneuver at low speeds is lost

Engineering Contradiction:
Improvecruising speedVSAvoidhovering capability
Core Design Contradiction:
SpeedVSAdaptability or versatility

Solution Approach 1:

The patent employs dynamic rotor inclination mechanisms that allow the rotors to change their orientation between vertical (for hovering) and horizontal (for forward flight). This dynamic reconfiguration enables the aircraft to adapt its lift generation mode based on operational requirements, resolving the contradiction between high-speed cruise capability and hovering capability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The aircraft design integrates multiple functions into a single platform: it can hover like a helicopter, cruise like an aeroplane, and transition between these modes. The convertible configuration system provides universality by enabling the same aircraft to perform diverse flight operations that traditionally required separate aircraft types.

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

2Adaptability or versatility

If helicopters rotate main rotor blades to generate lift for hovering and low-speed flight, then hovering capability and maneuverability are improved, but maximum operational altitude and speed are limited

Engineering Contradiction:
Improvehovering capabilityVSAvoidmaximum operational speed
Core Design Contradiction:
Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent utilizes dynamic rotor inclination to transition from vertical rotor orientation (helicopter mode for hovering) to horizontal rotor orientation (aeroplane mode for high-speed cruise). This dynamic reconfiguration allows the aircraft to overcome helicopter speed limitations while retaining hovering capability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The aircraft changes the orientation parameter of the rotors from vertical to horizontal, fundamentally altering the lift generation mechanism. This parameter change enables transition from rotor-based lift (limited speed) to wing-based aerodynamic lift (high speed capability).

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If convertiplanes use rotors inclinable with respect to the wing to switch between helicopter and aeroplane configurations, then versatility is improved, but device complexity increases

Engineering Contradiction:
Improveconfiguration flexibilityVSAvoid rotor inclination mechanism
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the rotor inclination mechanism with the wing structure itself, integrating the complexity into the existing airframe rather than adding separate complex systems. The rotors are inclinable with respect to the wing, combining lift generation and orientation control functions.

Inventive Principle:
Principle #5Merging (Combining)

4Speed

If aeroplanes accelerate on runways of considerable length to generate sufficient lift, then cruising speed is improved, but the requirement for long runways and complex infrastructure increases

Engineering Contradiction:
Improvecruising speedVSAvoidrunway length
Core Design Contradiction:
SpeedVSLength of moving object

Solution Approach 1:

The patent employs dynamic rotor inclination to enable vertical takeoff and landing (VTOL) capability. By inclining the rotors vertically, the aircraft can generate lift without runway acceleration, eliminating the need for long runways while maintaining high-speed cruise capability through subsequent rotor reconfiguration.

Inventive Principle:
Principle #15Dynamics

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 design achieves high stability and reduced aerodynamic drag, enhancing performance in both hovering and forward flight modes, suitable for sports and personal air mobility.

Implementation Method 1

a first plurality of rotors (20a, 20b; 21a, 21b) arranged above the fuselage (2) and rotatable around respective fixed axes (B, C; D, E) with respect to the fuselage (2)... adapted to generate a first lifting thrust

Methodology Applied
Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 2

a pair of half-wings (3) extending cantilevered from respective mutually opposite sidewalls (19) of the fuselage (2) and transversely to the axis (Y)... adapted to generate a lift value adapted to sustain the aircraft (1) arranged in the second configuration

Methodology Applied
Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 3

a tail portion (6) projecting cantilevered from a tail (5) of the fuselage (2)... an aerodynamic surface (8) adapted to generate a second lift/downforce value that ensures a desired degree of longitudinal stability

Methodology Applied
Scientific EffectAerodynamic stability: Aerofoil

Data Source

PatentEP4279383B1Convertible aircraft capable of hovering
Publication Date: 2025.12.17 LEONARDO SPA
  • EP4279383B1 patent drawingFigure 1
  • EP4279383B1 patent drawingFigure 2
  • EP4279383B1 patent drawingFigure 3

AI summary

An aircraft (1) comprising a fuselage (2, 2', 2") with a nose (4) and a tail (5) arranged on opposite parts to each other along a first longitudinal axis (Y) is described; a pair of half-wings (3) arranged on respective mutually opposite sides of the fuselage (2, 2', 2'); a first and a second rotor (22a, 22b) carried by respective half-wings (3), respectively rotatable around a second and third axis (F, G) inclinable with respect to said fuselage (2, 2', 2"), and independently operable from each other; the aircraft (1) is switchable between a first hovering flight or take-off/landing configuration wherein the fourth and fifth axis (F, G) are arranged orthogonal to said first axis (Y); and a second forward flight configuration wherein the fourth and fifth axis (F, G) are arranged parallel or inclined with respect to said first axis (Y); the aircraft (1) further comprising a tail portion (6) comprising a first aerodynamic surface (8), and a third and a fourth rotor (21a, 21b) rotatable around a fixed fourth and a fifth axis (D, E); and support means (31a, 31b) of the third and fourth rotor (21a, 21b) connected to a corresponding said half-wing (3) and to a corresponding said drift (52). (Figure 9)