Quad Tiltrotor Aircraft Rotor Disk Loading and Autorotation
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Solution Overview
Problem
Current tiltrotor aircraft designs face challenges in optimizing both vertical takeoff and landing capabilities and forward flight efficiency, with existing systems often compromising on lift and thrust performance.
Innovation Solution
The design incorporates higher disk-loading forward rotors and lower disk-loading aft rotors, with the aft rotors capable of autorotation and differential collective control, allowing for efficient transition between vertical lift and forward thrust orientations, optimizing lift in VTOL mode and thrust in forward flight mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If uniform disk-loading rotors are used in tiltrotor aircraft, then structural simplicity is maintained, but lift efficiency in VTOL mode and thrust efficiency in forward flight mode cannot be simultaneously optimized
Solution Approach 1:
The patent applies local quality by differentiating rotor disk-loading values across different locations of the aircraft. Forward rotors are designed with higher disk-loading optimized for thrust generation during forward flight, while aft rotors use lower disk-loading optimized for lift generation during VTOL operations. This localized optimization allows each rotor to perform its specific function more efficiently without requiring complete redesign of the entire rotor system.
2Power
If all rotors are actively driven during forward flight, then maximum thrust is available, but aerodynamic drag and power consumption increase
Solution Approach 1:
The patent extracts the driving function from aft rotors during forward flight mode. While forward rotors remain actively driven to generate thrust, aft rotors are allowed to autorotate freely without active power input. This extraction of the driving function from non-essential rotors reduces power consumption and aerodynamic drag while maintaining sufficient thrust through the forward rotors and fixed wings.
Solution Approach 2:
The patent implements dynamic control of rotor operation modes. Aft rotors can transition between actively driven mode during VTOL operations and autorotation mode during forward flight. This dynamic adjustment allows the aircraft to optimize power distribution based on flight phase, reducing energy loss during forward flight while maintaining lift capability when needed.
3Adaptability or versatility
If tiltrotor aircraft use conventional single-rotor configurations, then mechanical simplicity is maintained, but versatility in flight modes is limited
Solution Approach 1:
The patent segments the rotor system into multiple independent rotors (forward and aft rotors) that can be controlled separately. This segmentation allows different portions of the rotor system to perform different functions simultaneously - forward rotors for thrust and aft rotors for lift - enabling the aircraft to achieve multiple flight modes (VTOL, forward flight, hover) with a single configured system rather than requiring separate systems for each mode.
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
This configuration enhances lift efficiency during takeoff and landing while maximizing thrust efficiency during forward flight, improving overall aircraft performance and safety with features like autorotation in case of engine failure.
Implementation Method 1
The rotor systems are tiltable relative to a fixed wing such that the associated proprotors have a generally horizontal plane of rotation for vertical takeoff, hovering and vertical landing
Implementation Method 2
a generally vertical plane of rotation for forward flight, wherein the fixed wing provides lift
Implementation Method 3
The wings have an airfoil cross section that deflects air downwardly as the aircraft moves forward, generating vertical lift to support the airplane in flight
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1F
AI summary
A quad tiltrotor aircraft (10, 100, 200) has a longitudinally extending fuselage (12, 312) with forward and aft stations (14, 314; 16, 318). A forward wing (18, 320) having first and second outboard ends extends laterally from the forward station (14, 314). An aft wing (20, 324) having first and second outboard ends extends laterally from the aft station (16, 318). First and second forward rotors (26a, 26b, 112a, 112b, 212a, 212b, 330a, 330b) are respectively coupled proximate the first and second outboard ends of the forward wing (18, 320) and are tiltable relative to the forward wing (18, 320) between vertical lift and forward thrust orientations. First and second aft rotors (36a, 36b, 120a, 120b, 220a, 220b, 342a, 342b) are respectively coupled proximate the first and second outboard ends of the aft wing (20, 324) and are tiltable relative to the aft wing (20, 324) between vertical lift and forward thrust orientations. The forward rotors (26a, 26b, 112a, 112b, 212a, 212b, 330a, 330b) are higher disk-loading rotors than the aft rotors (36a, 36b, 120a, 120b, 220a, 220b, 342a, 342b). The aft rotors (36a, 36b, 120a, 120b, 220a, 220b, 342a, 342b) are foldable in the forward flight mode to provide extended range for the quad tiltrotor aircraft (10, 100, 200).