Tiltrotor Rotor Blade Folding for Compact Storage
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Solution Overview
Problem
Tiltrotor aircraft face challenges in reducing their footprint during storage, as fully cantilevered rotor blades can cause undesirably large moments on the drive system, potentially leading to damage.
Innovation Solution
The design includes a fuselage with a rotatable wing and pylon assemblies, where rotor blades are folded beamwise or chordwise to conform with the wing and pylon assemblies, allowing the wing to rotate parallel to the fuselage, reducing the aircraft's footprint and minimizing stress on the drive system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If rotor blades are fully cantilevered to one side of the drive system to minimize storage footprint, then the aircraft occupies less space during storage, but an undesirably large moment is placed on the drive system which may cause damage to bearings or other components
Solution Approach 1:
The rotor blade storage configuration is segmented into multiple positions rather than fully cantilevered to one side. The blades are arranged with some extending above the wing and some below, distributing the load across different locations relative to the drive system, thereby reducing the concentrated moment on bearings and components.
Solution Approach 2:
The rotor blades are positioned asymmetrically relative to the wing plane, with a specific arrangement where certain blades extend above and others below. This asymmetric configuration optimizes the distribution of gravitational moments on the drive system while maintaining a compact storage footprint, preventing excessive loading on any single bearing or component.
2Area of stationary object
If rotor blades are folded beamwise to conform with the wing and pylon assemblies, then the aircraft's storage footprint is reduced, but the complexity of the blade folding mechanism increases
Solution Approach 1:
The rotor blades are designed with dynamic folding capabilities, allowing them to transition between operational and storage configurations. The blades can fold beamwise to conform with the wing and pylon assemblies during storage, and unfold to their operational positions during flight, providing adaptability without requiring overly complex permanent structural modifications.
Solution Approach 2:
The spatial parameters of the rotor blades are changed during storage by folding them beamwise to conform with the wing and pylon assemblies. This parameter change reduces the aircraft's storage footprint while the folding mechanism is designed to manage the complexity through controlled movement and positioning rather than permanent structural complexity.
Data Source
AI summary
A tiltrotor aircraft having a VTOL flight mode, a forward flight mode and a storage mode includes a fuselage having a wing rotatably mounted thereto. The wing has an orientation generally perpendicular to the fuselage, in the flight modes, and an orientation generally parallel to the fuselage, in the storage mode. First and second pylon assemblies are positioned proximate outboard ends of the wing. First and second mast assemblies are respectively rotatable relative to the first and second pylon assemblies and have generally vertical orientations, in the VTOL flight mode, and generally horizontal orientations, in the forward flight mode and the storage mode. First and second proprotor assemblies are respectively rotatable relative to the first and second mast assemblies. Each proprotor assembly includes a plurality of rotor blades and has a radially extended orientation, in the flight modes, and a stowed orientation, in the storage mode.