Distributed Thrust Array for VTOL to Forward Flight Transition
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Solution Overview
Problem
Current aircraft designs face challenges in transitioning efficiently between thrust-borne lift in VTOL orientation and wing-borne lift in biplane orientation, particularly in maintaining hover stability and efficiently managing thrust vectors for diverse flight attitudes and payloads.
Innovation Solution
The aircraft employs a mission-configurable design with a two-dimensional distributed thrust array, featuring omnidirectional thrust vectoring propulsion assemblies and a redundant flight control system that allows independent control of each propulsion unit, enabling efficient transitions between VTOL and biplane orientations through speed control, thrust vectoring, and aerosurface maneuvers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If tiltrotor aircraft use fixed wing for forward flight, then speed and range are improved, but downwash inefficiencies occur during vertical takeoff and landing due to interference from the fixed wing
Solution Approach 1:
The aircraft divides the propulsion system into multiple independent proprotors distributed along the fuselage, with each proprotor capable of independent rotation and thrust generation. This segmentation allows the slipstream from each proprotor to strike the wing at optimal angles, improving vertical thrust efficiency during takeoff and landing while maintaining forward speed capability.
Solution Approach 2:
The proprotors are mounted in a distributed configuration along the fuselage rather than at single locations, creating a three-dimensional thrust distribution pattern. This dimensional arrangement optimizes the interaction between proprotor slipstream and wing surfaces, eliminating downwash inefficiencies while preserving forward flight performance.
2Loss of energy
If tiltwing aircraft rotate wing to vertical orientation for VTOL, then vertical thrust efficiency is improved, but control during hover becomes more difficult due to large surface area exposed to crosswinds
Solution Approach 1:
The aircraft segments the lifting surface into multiple smaller wing sections distributed along the fuselage, each associated with its own proprotor. This segmentation reduces the effective surface area exposed to crosswinds during hover while maintaining vertical thrust efficiency, and improves hover control by distributing aerodynamic forces across multiple locations.
Solution Approach 2:
Each proprotor-wing combination is designed as an independent local unit with optimized characteristics for its specific position on the fuselage. This local optimization allows each section to contribute effectively to vertical thrust while minimizing crosswind exposure, and enables independent control of each unit to improve overall hover stability.
3Ease of operation
If tiltwing aircraft add cyclic rotor control or additional thrust station for crosswind compensation, then hover control is improved, but device complexity increases
Solution Approach 1:
The distributed proprotor system serves multiple functions simultaneously: it provides vertical thrust during takeoff and landing, generates forward thrust during horizontal flight, and enables hover control through differential thrust adjustment. This multi-functionality eliminates the need for separate cyclic rotor control mechanisms or additional thrust stations, reducing overall system complexity while maintaining hover control capability.
Solution Approach 2:
The proprotors are designed with dynamic rotation capability, allowing each unit to rotate between vertical and horizontal orientations as needed. This dynamic reconfiguration enables the same propulsion system to adapt to different flight regimes (VTOL, hover, forward flight) without requiring separate control mechanisms for each mode, thereby reducing device complexity.
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 hover stability and enables efficient forward flight, allowing the aircraft to handle various payloads and flight attitudes, improving mission flexibility and operational efficiency.
Implementation Method 1
The rotor assembly having rotor blades that rotate in a rotational plane to generate thrust
Implementation Method 2
The wings generally have an airfoil cross section that deflects air downward as the aircraft moves forward, generating the lift force to support the airplane in flight
Implementation Method 3
Fixed-wing aircraft are capable of flight using wings that generate lift responsive to the forward airspeed of the aircraft, which is generated by thrust from one or more jet engines or propellers
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1F
AI summary
An aircraft (10) includes an airframe (12) and a distributed thrust array coupled to the airframe including at least six propulsion assemblies (24, 26). A flight control system (22) is operably associated with the distributed thrust array and is operable to independently control each of the propulsion assemblies. A package delivery module is coupled to the airframe. In a VTOL orientation utilizing thrust-borne lift, a first pair of propulsion assemblies is forward of the package delivery module, a second pair of propulsion assemblies is aft of the package delivery module and a third pair of propulsion assemblies is lateral of the package delivery module. In a forward flight orientation utilizing wing-borne lift, the first pair of propulsion assemblies is below the package delivery module, the second pair of propulsion assemblies is above the package delivery module and the third pair of propulsion assemblies is lateral of the package delivery module.