Hybrid Aircraft Propulsion with Fuel Cell Base and Peak Thrust Split

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Solution Overview

Problem

Existing aircraft propulsion systems face challenges in reducing mission contaminant emissions while maintaining high performance, particularly due to the higher weight and reduced performance of fuel cell-equipped aircraft compared to conventional systems.

Innovation Solution

A hybrid propulsion system combining fuel cell and combustion engines, where the fuel cell system provides base thrust during cruise and descent, and the combustion engines provide peak thrust during take-off and climb, controlled by a unified control unit to optimize power distribution based on load requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If fuel cell systems are used to propel aircraft, then contaminant emissions are reduced, but aircraft weight increases and performance decreases

Engineering Contradiction:
Improvecontaminant emissionsVSAvoidaircraft weight
Core Design Contradiction:
Object-generated harmful factorsVSWeight of moving object

Solution Approach 1:

The flight mission is divided into base load segments (cruise, descent, landing, taxiing) and peak load segments (take-off, climb). The fuel cell system is sized to provide only base thrust, while combustion engines provide peak thrust. This segmentation allows the fuel cell system to be smaller and lighter than a standalone fuel cell system would require.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines fuel cell propulsion with combustion engine propulsion in a hybrid architecture. The fuel cell system and combustion engines work together, with the fuel cell providing continuous base power and combustion engines providing supplemental peak power, achieving both emission reduction and performance maintenance.

Inventive Principle:
Principle #5Merging (Combining)

2Object-generated harmful factors

If fuel cell systems are used to propel aircraft, then contaminant emissions are reduced, but aircraft performance decreases

Engineering Contradiction:
Improvecontaminant emissionsVSAvoidaircraft performance
Core Design Contradiction:
Object-generated harmful factorsVSProductivity

Solution Approach 1:

The flight mission is divided into base load segments (cruise, descent, landing, taxiing) and peak load segments (take-off, climb). The fuel cell system is sized to provide only base thrust, while combustion engines provide peak thrust. This segmentation allows the fuel cell system to be smaller and lighter than a standalone fuel cell system would require.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines fuel cell propulsion with combustion engine propulsion in a hybrid architecture. The fuel cell system and combustion engines work together, with the fuel cell providing continuous base power and combustion engines providing supplemental peak power, achieving both emission reduction and performance maintenance.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If combustion engines are operated continuously to provide peak thrust, then aircraft performance is maintained, but contaminant emissions increase

Engineering Contradiction:
Improveaircraft performanceVSAvoidcontaminant emissions
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The control unit dynamically adjusts the operation of combustion engines based on real-time thrust requirements. Combustion engines are operated only when peak thrust is needed (take-off, climb, or specific conditions), and turned off during base load segments. This dynamic operation minimizes emission-generating events while maintaining performance when required.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control unit monitors flight conditions and thrust requirements, and adjusts combustion engine operation accordingly. The system receives feedback about mission segment and thrust needs, and optimizes the operation of combustion engines to provide peak thrust only when necessary, reducing overall emissions.

Inventive Principle:
Principle #23Feedback

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 approach significantly reduces contaminant emissions by up to 60% while minimizing weight and drag, maintaining high performance by leveraging the strengths of both propulsion types, with zero emissions during certain mission segments.

Implementation Method 1

a fuel cell unit for providing power to drive an aircraft by using hydrogen in a redox reaction

Methodology Applied
Scientific EffectRedox reaction: Redox Reactions

Implementation Method 2

a combustion unit for providing power to drive an aircraft by burning hydrogen

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP4173956B1Hybrid propulsion system for propelling an aircraft, method of operating same, and hybrid aircraft
Publication Date: 2026.03.18 AIRBUS (SAS)
  • EP4173956B1 patent drawingFigure 1
  • EP4173956B1 patent drawingFigure 2

AI summary

A hybrid propulsion system for propelling an aircraft (100) comprises a first propulsion system (11) based on fuel cells and a second propulsion (12) system based on one or more combustion engines (15, 16). The first propulsion system (11) is fully providing a base thrust (A). The second propulsion system (12) is providing a peak thrust (B) needed for take-off of the aircraft (100) and/or is assisting the first propulsion system (11) in propelling the aircraft (100) when the peak thrust (B) is needed or in failure conditions.