Tiltable Pylon Mount for Coaxial Rotorcraft
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Solution Overview
Problem
Conventional dual counter-rotating coaxial rotor systems face excessive hub moments during maneuvers, leading to inflight rotor interference and intermeshing due to rigid pylon mounting systems.
Innovation Solution
A mount system with pylon links oriented to create a virtual pivot point proximate the coaxial rotor system, allowing the pylon assembly to tilt and counteract lateral and fore/aft moments, featuring spherical bearings and a torque restraint and vibration isolation subsystem to manage these forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid pylon mounting systems are used in dual counter-rotating coaxial rotor systems, then structural strength and stability are improved, but excessive hub moments are generated during maneuvers causing rotor interference and intermeshing
Solution Approach 1:
The patent applies dynamics by transitioning from a rigid pylon mounting system to a dynamic mount system with pylon links that allow the pylon assembly to tilt relative to the airframe. The pylon links connect the pylon assembly to the airframe in a manner that permits angular movement, enabling the system to adapt during maneuvers and reduce excessive hub moments that cause rotor interference.
Solution Approach 2:
The patent changes the geometric parameters of the mounting system by orienting the pylon links such that their axes intersect at a focal point located proximate to the coaxial rotor system. This specific geometric configuration creates a virtual pivot point that allows the pylon assembly to tilt in a controlled manner, changing the moment parameters during maneuvers to prevent rotor interference.
2Ease of manufacture
If rigid pylon mounting systems are used, then manufacturing simplicity is improved, but rotor interference and intermeshing occur during maneuvers
Solution Approach 1:
The mount system with pylon links introduces dynamic capability to the pylon assembly, allowing it to tilt and adjust its orientation during flight maneuvers. This dynamic adjustment prevents rotor interference and intermeshing by reducing excessive hub moments, thereby improving reliability without significantly complicating manufacturing.
Solution Approach 2:
The patent segments the rigid pylon structure into multiple pylon links that connect the pylon assembly to the airframe. Each pylon link functions as an independent structural element, allowing relative movement between them. This segmentation enables the system to accommodate maneuver-induced moments while maintaining manufacturing feasibility through modular construction.
3Object-affected harmful factors
If the pylon assembly is made tiltable to reduce hub moments, then rotor interference is prevented, but structural complexity increases
Solution Approach 1:
The patent implements tilting capability through pylon links that naturally permit angular movement without requiring complex active control mechanisms. The tilting action is passive and driven by aerodynamic forces during maneuvers, reducing hub moments to prevent rotor interference while avoiding the need for motors, sensors, or control systems that would increase complexity.
Solution Approach 2:
The patent achieves hub moment reduction through a specific geometric parameter configuration where the pylon link axes intersect at a focal point proximate to the rotor system. This geometric arrangement creates a virtual pivot point that enables effective tilting action. The solution changes the spatial parameters of the mounting system rather than adding complex mechanical components.
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
The solution effectively reduces peak moment magnitudes and smooths moment curves, preventing excessive lateral and fore/aft moments, thus avoiding rotor interference and intermeshing, and enhancing rotorcraft stability during maneuvers.
Implementation Method 1
The first, second, third and fourth pylon links may be coupled to the pylon assembly and the airframe with spherical bearings
Data Source
AI summary
A mount system for tiltably supporting a pylon assembly of a rotorcraft. First, second, third and fourth pylon links are each coupled between the pylon assembly and the airframe of the rotorcraft. The first pylon link has a first axis, the second pylon link has a second axis, the third pylon link has a third axis and the fourth pylon link has a fourth axis. Each of the axes intersects at a focal point located proximate a coaxial rotor system having counter-rotating upper and lower rotor assemblies such that the focal point provides a virtual pivot point about which the pylon assembly tilts to generate a control moment about a center of gravity of the rotorcraft that counteracts lateral and fore/aft moments generated by the upper and lower rotor assemblies during rotorcraft maneuvers.