Open Rotor Differential Drive With Brake for Ground Safety

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Open rotor aircraft propulsion systems pose safety risks to ground personnel due to the larger diameter fan/rotor and lack of a fan duct, which increases the volume of bypass airflow outside the engine nacelle, potentially bringing the rotor closer to accessible doors and increasing injury risks.

Innovation Solution

The system incorporates a powertrain that can transfer power to the propulsor rotor and compressor during one mode and isolate the propulsor rotor from its drive mechanism, allowing it to be slowed or stopped using a braking mechanism without affecting the engine, and includes a power turbine isolation system to decouple power from the propulsor rotor when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the fan rotor diameter is increased to generate more bypass airflow and thrust, then the propulsion performance is improved, but the safety risk to ground personnel increases due to larger rotor diameter and lack of fan duct enclosure

Engineering Contradiction:

ImprovethrustVSAvoidsafety risk to ground personnel

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The power transmission system is segmented into independent controllable paths. The differential gear system allows the rotor drive shaft to be decoupled from the power source, enabling independent control of rotor rotation while maintaining engine operation. This segmentation permits the rotor to be stopped for ground safety while the engine continues to generate power for other functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from a fixed rigid power connection to a dynamic controllable connection. The differential mechanism and brake system enable the rotor to dynamically change its rotational state (rotating during flight, stopped during ground operations) while the engine maintains operational flexibility. This dynamic control resolves the safety concern by allowing rotor shutdown when on the ground while preserving thrust-generating capability when in flight.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the fan rotor is positioned further forward to increase distance from the wing and reduce airflow interference, then the aerodynamic performance is improved, but the safety risk to ground personnel increases by moving the rotor closer to accessible doors

Engineering Contradiction:

Improveaerodynamic performanceVSAvoidsafety risk to ground personnel

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The differential gear system acts as an intermediary mechanism between the engine power source and the rotor. It provides a mechanical decoupling that allows the rotor to be independently controlled and stopped via the brake system, while the engine remains operational. This intermediary mechanism resolves the conflict between aerodynamic positioning requirements and ground safety concerns.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If a brake system is added to stop the propulsor rotor during ground operations, then the safety risk to ground personnel is reduced, but the device complexity increases

Engineering Contradiction:

Improvesafety risk to ground personnelVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The differential gear system serves multiple functions: it enables power distribution to both the rotor and compressor, provides mechanical decoupling for independent rotor control, and works with the brake system to enable rotor shutdown. This multi-functionality reduces the need for separate dedicated braking mechanisms, thereby limiting the increase in device complexity while achieving the safety benefit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The differential mechanism inherently provides the capability to isolate the rotor from the power source through its mechanical design. When the brake is applied, the differential naturally redirects power flow to the compressor while the rotor stops, without requiring additional complex control systems. The system uses its own existing mechanical structures to achieve the braking function.

Inventive Principle:

Principle #25Self-service

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 configuration reduces the risk of injury to ground personnel by stopping the propulsor rotor during ground operations and maintains engine functionality by redirecting power to other assemblies, enhancing safety without adversely affecting performance.

Implementation Method 1

a braking mechanism without affecting the engine

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12565328B2Differential driven open rotor with brake

Publication Date: 2026.03.03 RTX CORP

AI summary

An assembly for an aircraft propulsion system includes an open propulsor rotor and a powertrain configured to receive power from a turbine and drive both the propulsor rotor and a compressor section at the same time in a first mode of operation. In a second mode of operation, a brake is applied that stops rotation of the propulsor rotor and the turbine power received by the powertrain drives only the compressor section. In the second mode, the propulsor rotor is stationary or otherwise undriven which effectively prevents rotation of the propulsor rotor. This reduces or eliminates safety risks to ground crews resulting from an open propulsor rotor actively rotating as the aircraft is on the ground.