Oil Lubricated Swashplate Thermal Management
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Solution Overview
Problem
Rotating wing aircraft are limited in maximum flight speed due to phenomena such as retreating blade stall, increased drag at rotor tips, and reverse airflow over retreating blades, which restrict their top speed to less than 200 mph.
Innovation Solution
A rotor system with a swashplate and thermal management system, including a mast, rotor hub, and pitch control rods, along with a thermal modulator and compressed air source, is used to maintain preloaded bearing conditions and optimize rotor performance, allowing for higher flight speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If autorotation of rotor is used to provide lift, then vertical takeoff and landing capability is achieved, but maximum flight speed is limited to less than 200 mph due to retreating blade stall and increased drag at rotor tips
Solution Approach 1:
The patent applies dynamics by making the rotor system adaptable between powered and unpowered rotation modes. The rotor blades are designed to transition from forced rotation during takeoff and hovering to autorotation during high-speed flight, allowing the system to optimize performance for different flight regimes and overcome the speed limitation imposed by retreating blade stall
Solution Approach 2:
The patent changes the operational parameters of the rotor system by varying the rotation mode (powered vs. unpowered) and blade pitch angles. During high-speed flight, the rotor operates in unpowered autorotation with specific pitch settings that reduce drag and prevent retreating blade stall, thereby enabling speeds exceeding 200 mph while maintaining vertical takeoff capability
2Reliability
If preloaded bearing condition is maintained in thermal management system, then rotor performance is optimized, but system complexity increases due to thermal modulator and oil circulation system
Solution Approach 1:
The patent applies self-service by using the heat generated from bearing friction and rotor operation to maintain the preloaded condition. The oil circulation system absorbs heat during normal operation, and when cooling is needed, the same system dissipates heat through radiation or convection without requiring external active cooling components, thus maintaining reliability while limiting complexity
Solution Approach 2:
The patent uses hydraulics through the oil circulation system that flows through channels in the rotor hub and bearing assemblies. The oil serves dual purposes: lubrication and thermal management. The hydraulic system maintains preloaded bearing conditions by controlling oil temperature and pressure, optimizing rotor performance through a integrated fluid management approach
3Measurement precision
If pitch control rods and swashplate are used to control rotor blades, then flight control precision is improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing the swashplate and pitch control rods to perform multiple functions: controlling blade pitch angles for both collective and cyclic control, maintaining blade synchronization during transition between powered and autorotation modes, and providing structural support for the rotor hub assembly. This reduces the need for separate control systems and minimizes overall complexity while maintaining precision
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 vertical takeoff and landing while achieving flight speeds exceeding 200 mph by reducing drag and stabilizing rotor performance through advanced thermal management and pitch control.
Implementation Method 1
The bearing includes a plurality of rolling elements, the plurality of rolling elements having a preloaded condition within an operating temperature range
Implementation Method 2
A feed oil line and a return oil line are in fluid communication with the bearing
Data Source
AI summary
A rotor system for a reactive drive rotary wing maintains the rigidity of the rotor and eliminates play between flight controls and the rotor by mounting swashplate actuators to a flange rigidly secured to the mast. Apparatus and methods perform thermal management of the rotor in order to avoid bearing failure or loss of bearing preload. Methods include modulating the temperature of oil pumped over one or more of the mast bearing, swashplate bearing, and spindle bearing. The temperature of air passively or actively drawn through rotor may also be modulated to maintain bearing temperature within a predetermined range. The rotor includes structures for reducing pressure losses and drag on components due to air flow through the rotor. A rotor facilitates thermal management by oil and air flow.