Tiltrotor Outboard Engine Rotor System
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Solution Overview
Problem
Tiltrotor aircraft engines face limitations due to the need for vertical and horizontal operation, increased maintenance, and complex mounting structures, which restrict engine choices and maintenance access.
Innovation Solution
A rotor system with upper and lower outboard engines fixed on the wing, a prop-rotor pylon that rotates between vertical and horizontal positions, and an aerodynamic nacelle with air inlet systems to direct airflow, allowing for efficient power transmission and reduced maintenance complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the engine is located in the rotating nacelle to enable tiltrotor operation, then the aircraft can operate in both helicopter and airplane modes, but the engine must be configured and certified for both vertical and horizontal orientations which limits engine choices and increases certification costs
Solution Approach 1:
The system separates the engine (fixed on wing) from the rotating component (prop-rotor pylon with gearbox). This segmentation allows the engine to remain stationary while only the necessary propulsion components rotate, eliminating the need for complex rotating engine mounts and dual-orientation certification.
Solution Approach 2:
A fixed intermediary component (gearbox mounted on the wing) is introduced between the engine and the rotating pylon. The gearbox serves as a stationary power transmission interface that converts engine power to the rotating pylon, eliminating the need for the engine itself to rotate or be certified for multiple orientations.
2Power
If the engine is located in the rotating nacelle, then power can be transmitted to the rotor, but the rotating engine requires more maintenance and complex mounting structures that limit maintenance and inspection access
Solution Approach 1:
The system divides the power transmission function into separate components: a fixed engine, a stationary gearbox mounted on the wing, and a rotating pylon. This segmentation allows maintenance personnel to access the engine and gearbox from fixed positions without dealing with rotating mounting structures, significantly improving maintenance access and ease of repair.
3Device complexity
If a single engine is used in the nacelle, then the structure is simplified, but power availability in case of engine failure is reduced and operational weights are limited
Solution Approach 1:
The system merges multiple engines (upper and lower outboard engines) into a single integrated power transmission system through the gearbox and common pylon. This merging allows multiple engines to operate simultaneously, providing redundant power availability and increased operational weights while maintaining structural efficiency through the shared rotating components.
Data Source
AI summary
In a first aspect, there is a rotor system for a tiltrotor aircraft, the rotor system including an upper outboard engine in a fixed location on a wing member of the tiltrotor aircraft; a lower outboard engine in a fixed location on the wing member; and a prop-rotor pylon in power communication with the upper and lower outboard engines, the prop-rotor pylon being configured to selectively rotate between a vertical position and a horizontal position. In another aspect, there is provided a tiltrotor aircraft including a fuselage; a wing member; an upper outboard engine in a fixed location on the wing member; a lower outboard engine in a fixed location on the wing member; and a prop-rotor pylon in power communication with the upper and lower outboard engines, the prop-rotor pylon being configured to selectively rotate between a vertical position and a horizontal position.