Intermittent Combustion Aircraft Propulsion With Variable-Speed Rotors

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Solution Overview

Problem

There is a need for more cost-effective and fuel-efficient propulsion system configurations for aircraft, particularly business jets, which operate at high altitudes and fast speeds.

Innovation Solution

A propulsion system for aircraft utilizing an intermittent combustion engine with a remote powerplant configuration, including a turbo-compounded or turbocharged intermittent combustion engine housed within the aircraft fuselage, coupled to ducted or open rotors through variable speed transmissions and drivetrains, which facilitate rotation of propulsor rotors at varying speeds and directions, optimizing thrust and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If small gas turbine engines are used for high altitude and fast speed flight, then aircraft propulsion capability is improved, but manufacturing and servicing costs increase

Engineering Contradiction:
Improveaircraft speedVSAvoidmanufacturing and servicing costs
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The patent applies this principle by using a reciprocating engine with piston cylinders that can be more easily manufactured and serviced compared to gas turbine engines. The simpler mechanical components allow for lower manufacturing costs and easier maintenance, directly addressing the cost issue while maintaining propulsion capability for high-speed flight

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Speed

If small gas turbine engines are used for high altitude flight, then aircraft propulsion capability is improved, but fuel efficiency deteriorates

Engineering Contradiction:
Improveaircraft speedVSAvoidfuel efficiency
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The patent employs parameter changes by utilizing a reciprocating engine with variable valve timing and compression ratios that can be optimized for different flight conditions. The engine can adjust its operating parameters to maintain fuel efficiency across a range of altitudes and speeds, unlike fixed-parameter gas turbine engines

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If variable speed transmissions are used to facilitate rotation of propulsor rotors at varying speeds, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improveadjustable thrustVSAvoidtransmission system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by using variable speed transmissions that allow the propulsor rotors to rotate at different speeds independent of the engine crankshaft speed. This enables the system to adapt thrust output to varying flight conditions while managing complexity through controlled variability rather than complete system redesign

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 system reduces manufacturing and servicing costs, enhances fuel efficiency, and allows for adjustable thrust without significant changes in powerplant rotational speed, improving aircraft performance at high altitudes and speeds.

Implementation Method 1

Aircraft propulsion systems may include an intermittent combustion engine (ICE)

Methodology Applied
Scientific EffectIntermittent combustion: Combustion

Implementation Method 2

The aircraft powerplant may be configured as a turbo-compounded intermittent combustion engine

Methodology Applied
Scientific EffectTurbine: Turbine

Data Source

PatentEP4306422B1Aircraft propulsion system with intermittent combustion engine(s)
Publication Date: 2026.04.01 PRATT & WHITNEY CANADA CORP
  • EP4306422B1 patent drawingFigure 1
  • EP4306422B1 patent drawingFigure 2
  • EP4306422B1 patent drawingFigure 3

AI summary

An aircraft system is provided that includes a first propulsor rotor (42A), a first transmission (106A), a second propulsor rotor (42B), a second transmission (106B) and an intermittent combustion engine (68). The first propulsor rotor (42A) is rotatable about a first propulsor axis (48A). The first transmission (106A) is coupled to the first propulsor rotor (42A). The second propulsor rotor (44) is rotatable about a second propulsor axis (48B). The second transmission (106B) is coupled to the second propulsor rotor (44). The intermittent combustion engine (68) is configured to drive rotation of the first propulsor rotor (42) through the first transmission (106A). The intermittent combustion engine (68) is configured to drive rotation of the second propulsor rotor (44) through the second transmission (106B).