RAT Mounting Frame Resonance Control
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Solution Overview
Problem
Ram air turbines (RATs) in aircraft experience resonance modes that can damage the turbine and support structure when these modes align with dynamic loading frequencies, making it challenging to manufacture a high-stiffness mounting structure that is both lightweight and cost-effective, and complicates RAT installation.
Innovation Solution
A mounting system comprising a frame with front and rear support blocks, top and bottom plates, and diagonal braces that attach to the aircraft using lugs and rods, shifting the harmonic frequency range of resonance modes away from the operating range of the RAT, thereby reducing the likelihood of resonance-induced damage and facilitating installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stiffness of the support structure is substantially increased to move resonance frequencies away from operating range, then the resonance damage risk is reduced, but the weight and manufacturing cost increase significantly
Solution Approach 1:
The mounting structure is divided into modular components including front support blocks, rear support blocks, lateral plates, and diagonal braces. Each segment can be independently manufactured and optimized, allowing the overall structure to achieve high stiffness without requiring a single heavy monolithic component. The segmentation enables precise placement of stiffening elements where most needed.
Solution Approach 2:
The invention adds diagonal braces that introduce bracing in the lateral dimension, creating a three-dimensional rigid framework. This diagonal bracing approach transforms a potentially planar structure into a spatial truss system, dramatically increasing stiffness-to-weight ratio by utilizing the third dimension for load path optimization.
2Reliability
If the stiffness of the support structure is substantially increased to move resonance frequencies away from operating range, then the resonance damage risk is reduced, but the manufacturing cost increases significantly
Solution Approach 1:
By segmenting the mounting structure into standardized blocks and plates, each component can be manufactured using conventional machining processes rather than requiring expensive custom fabrication. The modular design allows for economies of scale and simplified quality control, reducing overall manufacturing cost while maintaining high stiffness.
Solution Approach 2:
The invention combines multiple structural functions into integrated components. For example, the support blocks serve both as mounting interfaces and as stiffening elements, while the diagonal braces simultaneously provide structural rigidity and load path optimization. This functional merging reduces the total number of parts and assembly steps, lowering manufacturing cost.
3Reliability
If a frame structure is added to the RAT assembly, then the resonance frequencies are shifted away from operating range, but the installation complexity increases
Solution Approach 1:
The frame structure is segmented into pre-assembled modules (front support block with lateral plate, rear support block with lateral plate, diagonal braces) that can be manufactured and tested independently before final installation. This segmentation allows for pre-integration of complex features, reducing on-site assembly complexity and installation time.
Solution Approach 2:
The support blocks are designed with universal mounting interfaces that can accommodate various RAT configurations and aircraft types. The standardized interfaces and modular design allow the same frame structure to serve multiple functions: structural support, resonance frequency control, and easy installation/removal, thereby reducing overall system complexity.
Data Source
AI summary
A mounting frame for a ram air turbine includes a front support block having a top side opposite a bottom side. A rear support block is disposed opposite the front support block, the rear support block also having a top side, and a bottom side. A top plate extends between the front support block and the rear support block, the top plate having a forward end connected to the front support block proximate the top side of the front support block, an aft end connected to the rear support block proximate the top side of the rear support block. A bottom plate extends between the front support and the rear support opposite the top plate.