Ram Air Turbine Compound Geartrain for Ground Testing
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Solution Overview
Problem
Existing ram air turbine power systems (RATPS) are difficult to test on the ground and maintain, requiring risky in-flight testing and complex disassembly for component replacement, with components often operating at compromised speeds.
Innovation Solution
A gearbox with multiple output shafts and energy conversion devices that allow for on-ground testing and easy replacement of components, with each device operating at its optimized rotational speed, facilitated by a compound geartrain and testing port.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If in-flight testing is performed to ensure operational readiness of RATPS, then the reliability of power system testing is improved, but the safety risk increases
Solution Approach 1:
A testing port is introduced as an intermediary interface that allows ground-based testing equipment to connect with the RATPS turbine shaft. This mediator enables power system testing on the ground without requiring actual flight conditions, thus eliminating safety risks while maintaining reliability verification capability.
2Power
If the RATPS is constructed as an integrated combination of turbine, generator and pump with separate reduction gearing, then the power transmission efficiency is improved, but the ease of repair deteriorates
Solution Approach 1:
The integrated RATPS is segmented into modular components (turbine, generator, pump, gearbox) that can be independently removed and replaced. The gearbox serves as a common interface that accepts multiple energy conversion devices, allowing defective components to be exchanged without complete disassembly of the entire system.
Solution Approach 2:
The gearbox is designed with universal mounting flanges and standardized interfaces that can accommodate different energy conversion devices (generator, pump, or other devices). This multi-functionality allows the same gearbox structure to support various components, simplifying maintenance and component interchangeability.
3Ease of repair
If both generator and pump are driven by the same rotating shaft in the Cohen RATPS, then the ease of repair is improved, but the use of energy deteriorates
Solution Approach 1:
The power transmission path is segmented into separate branches from the turbine shaft, with independent reduction gearing for the generator and pump. This allows each energy conversion device to operate at its own optimized speed while maintaining modular architecture for easy repair.
Solution Approach 2:
The gearbox incorporates variable ratio transmission paths that can dynamically adjust the rotational speed delivered to each energy conversion device. This enables the generator and pump to operate at different optimized speeds rather than being constrained to a single common speed, thereby improving overall system energy efficiency.
4Reliability
If periodic testing is performed during normal flight, then the operational readiness is verified, but the loss of time for safe testing increases
Solution Approach 1:
The testing port enables preliminary ground-based testing of the RATPS before actual flight operations. By performing testing in advance on the ground where safety risks are eliminated, the need for risky in-flight testing is reduced or eliminated, saving time and improving safety.
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 reliable on-ground testing and cost-effective maintenance of RATPS, reducing the risk of in-flight testing and allowing for efficient replacement of components without disassembling the entire system, while maintaining optimal operational speeds.
Implementation Method 1
a ram air turbine is exposed to an air stream outside the aircraft. The ram air turbine drives a generator and/or a hydraulic pump
Data Source
AI summary
An emergency power system may provide hydraulic and electrical power to an aircraft in the event of a failure of the aircraft's primary control power system. The system may be constructed as a ram air turbine in which a single ram air fan may drive both a hydraulic pump and an electrical generator. A unique gearbox may incorporate compound gearing to permit the pump and the generator to be driven at different speeds. Thus the pump and the generator may be driven at their respective optimum speeds. The pump and the generator may be detachably mounted on a gearbox that supports the ram air fan. The detachable mounting of the pump and generator may accommodate ease of maintenance of these items. The gearbox may be provided with a ground testing port through which rotational testing force may be introduced to a shaft that supports the ram air fan. This may permit ground level testing of the system. Ground level testing may reduce a need to perform periodic in-flight testing of the system.