VTOL Aircraft With Independently Tiltable Forward and Aft Proprotors
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Solution Overview
Problem
Winged VTOL aircraft with non-tiltable rotors face issues such as increased drag, noise, vibration, and structural weight due to two-bladed rotors, which are fixed during forward flight, leading to unsteady aerodynamic and gyroscopic loading.
Innovation Solution
Aircraft design featuring independently tiltable proprotors mounted forward and aft of the wing, allowing all proprotors to be used during all flight stages, with at least three blades per propeller to reduce drag and noise, and enabling independent tilt control for enhanced thrust and yaw control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If two-bladed rotors are used for non-tiltable rotors during forward flight, then drag is reduced, but unsteady aerodynamic and gyroscopic loading increases causing increased noise, vibration, and structural weight
Solution Approach 1:
The patent applies the dynamics principle by making the rotors tiltable rather than fixed. The rotors can dynamically adjust their tilt angle between vertical (for lift during hover) and horizontal (for thrust during forward flight) positions. This dynamic adaptability allows the system to optimize performance for different flight phases, eliminating the need to use two-bladed configuration during forward flight and thereby reducing noise and vibration while maintaining low drag characteristics.
2Loss of energy
If two-bladed rotors are used, then drag is reduced, but heavier aircraft components are required to withstand increased vibration
Solution Approach 1:
The tiltable rotor design eliminates the need for heavy vibration-resistant components by avoiding the unsteady aerodynamic and gyroscopic loading that occurs with fixed two-bladed rotors. The dynamic adjustment capability allows smooth transition between flight modes without the harsh vibrations that would require reinforced structures.
Solution Approach 2:
The patent changes the operational parameters of the rotors by enabling tilt angle adjustment. This parameter change transforms the rotor system from a fixed configuration to a variable one, allowing optimization for different flight conditions. By changing the tilt parameter, the system achieves both low drag and low vibration characteristics without requiring heavier components.
3Device complexity
If non-tiltable rotors are used during forward flight, then structural simplicity is maintained, but thrust requirement from propulsion system increases
Solution Approach 1:
The tiltable rotor system dynamically reconfigures itself for different flight phases. During forward flight, the rotors tilt to a horizontal position to provide optimal thrust, while during hover they tilt vertically for lift. This dynamic reconfiguration allows the same rotor system to serve both functions efficiently, reducing the overall power requirement compared to a non-tiltable system that would need to overcome both lift and drag requirements simultaneously.
4Ease of operation
If all proprotors are independently tiltable, then thrust distribution and yaw control are improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the rotor system into multiple independently controllable proprotors. Each proprotor can be tilted independently relative to the others, allowing differential thrust control. This segmentation enables precise control of thrust distribution across the aircraft and provides yaw control capability, with each segment responding independently to control inputs.
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 design reduces drag and noise, increases structural efficiency, and provides redundancy and yaw control, allowing smaller proprotor sizes and improved thrust distribution, even in failure conditions.
Implementation Method 1
Some VTOL aircraft generate lift entirely through its propulsion system in all stages of flight. While other VTOL aircraft have wings to provide lift required during forward flight.
Implementation Method 2
At least some of the rotors may be tiltable to provide forward thrust during forward flight.
Implementation Method 3
Each of the proprotors can be independently tilted for providing vertical thrust during hover and for providing forward thrust during cruise.
Data Source
AI summary
A vertical take-off and landing aircraft may include a fuselage; at least one wing connected to the fuselage; a first plurality of proprotors mounted to the at least one wing, positioned at least partially forward of a leading edge of the at least one wing, and tiltable between lift configurations for providing lift for vertical take-off and landing of the aircraft and propulsion configurations for providing forward thrust to the aircraft; and a second plurality of proprotors mounted to the at least one wing, positioned at least partially rearward of a trailing edge of the at least one wing, and tiltable between lift configurations for providing lift for vertical take-off and landing of the aircraft and propulsion configurations for providing forward thrust to the aircraft; wherein the first plurality of proprotors and the second plurality of proprotors are independently tiltable.