Hybrid Ejector-Propeller Propulsion for VTOL Flight Switching

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Solution Overview

Problem

Existing VTOL and STOL aircraft face challenges in achieving high performance with compact footprint, low noise, reliable operation, and reduced landing-space requirements, while maintaining efficient fuel usage and simplicity in propulsion systems.

Innovation Solution

A propulsion system that seamlessly switches between a fluidic propulsive system (FPS) thruster/ejector and a turboprop, utilizing a gas generator connected to a turbine and thrusters with variable faceplates, allowing for efficient transition between vertical and horizontal flight modes, and integrating a gear mechanism for RPM conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a gas generator is connected to both a turbine and multiple ejectors with variable faceplates, then the system can switch between vertical and horizontal flight modes, but the device complexity increases

Engineering Contradiction:
Improveflight mode switching capabilityVSAvoidpropulsion system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The gas generator is designed to serve multiple functions by connecting to both a turbine for horizontal flight and multiple ejectors with variable faceplates for vertical flight, allowing a single power source to enable both VTOL and STOL capabilities

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

Solution Approach 2:

Variable faceplates on the ejectors allow dynamic adjustment of thrust vectoring, enabling the system to transition between different flight modes by changing the direction and distribution of exhaust gases in real-time

Inventive Principle:
Principle #15Dynamics

2Productivity

If a gear mechanism is integrated for RPM conversion between turbine and propeller, then the system achieves efficient RPM matching, but the device complexity increases

Engineering Contradiction:
ImproveRPM conversion efficiencyVSAvoidmechanism complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

A gear mechanism serves as an intermediary between the turbine and propeller, converting RPM at the turbine to appropriate RPM at the propeller, enabling efficient power transmission across different rotational speed requirements

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If the faceplate closes completely to force gas flow over the turbine, then horizontal flight efficiency improves, but the loss of substance increases due to restricted exhaust paths

Engineering Contradiction:
Improvehorizontal flight efficiencyVSAvoidexhaust gas flow restriction
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The faceplate is designed to be variable and dynamically adjustable, closing completely during horizontal flight to direct all exhaust over the turbine for maximum efficiency, while allowing partial opening during transition phases to manage exhaust flow distribution

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

Enables unprecedented performance with better reliability, lower noise, compact design, and reduced operating costs by simplifying mechanisms, while providing fuel savings and enhanced aircraft dynamics.

Implementation Method 1

a nozzle to accelerate and expand the hot, pressurized gas from the gas generator into the turbine

Methodology Applied
Scientific EffectGas expansion: Adiabatic Cooling

Implementation Method 2

the turbine- the turbine accelerates and starts driving the propeller

Methodology Applied
Scientific EffectTurbine energy conversion: Turbine

Implementation Method 3

driving the correct RPM (reduction gear) from a high RPM of the turbine to the low RPM of the large propeller

Methodology Applied
Scientific EffectPropeller thrust generation: Aerofoil

Data Source

PatentEP3793898B1Combination compressed-fluid ejector and propeller propulsion system
Publication Date: 2025.11.05 JETOPTERA INC
  • EP3793898B1 patent drawingFigure 1
  • EP3793898B1 patent drawingFigure 2~3
  • EP3793898B1 patent drawingFigure 4

AI summary

A propulsion system includes a source of compressed fluid, at least one thruster in fluid communication with the source, at least one turbine in fluid communication with the source and coupled to a propeller, and an apparatus for selectively providing the compressed fluid to one or both of the at least one thruster and the at least one turbine.