Distributed Thrust Array VTOL Aircraft Transition Control
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Solution Overview
Problem
Current aircraft designs face challenges in transitioning efficiently between vertical takeoff and landing (VTOL) and wing-borne lift orientations, particularly due to downwash inefficiencies and control difficulties during hover and forward flight.
Innovation Solution
An aircraft with a two-dimensional distributed thrust array and a flight control system that allows independent control of rotor speed and thrust vector, enabling transitions between VTOL and biplane orientations based on thrust-to-weight configuration, using pitch down attitudes and collective thrust vectoring to maintain hover stability and initiate forward flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If tiltrotor aircraft use fixed wing during vertical takeoff and landing, then forward flight speed is improved, but downwash inefficiencies occur due to interference from the fixed wing
Solution Approach 1:
The aircraft divides the lift-generating function between two separate systems: the fixed wing for forward flight and the proprotors for vertical flight. This segmentation allows each component to operate independently in its optimal configuration, eliminating the energy loss from wing interference during VTOL operations.
Solution Approach 2:
The proprotors are designed to dynamically change their plane of rotation from horizontal during VTOL to vertical during forward flight. This dynamic reconfiguration allows the aircraft to optimize performance for each flight regime without the fixed wing interfering with downwash during vertical operations.
2Power
If tiltwing aircraft rotate wing to vertical orientation for VTOL, then vertical thrust efficiency is improved, but control difficulty increases during hover due to large surface area for crosswinds
Solution Approach 1:
The aircraft separates the thrust-generating function from the control surface function. The proprotors provide vertical thrust during hover while the horizontal stabilizer and elevator provide pitch control, eliminating the control difficulties associated with using a vertically-oriented wing as both thrust and control surface.
Solution Approach 2:
Instead of using the vertically-oriented wing for both thrust and control (as in tiltwing designs), the invention inverts the approach by using the proprotors for thrust and a fixed horizontal stabilizer for control, reversing the conventional assignment of functions.
3Stability of the object's composition
If aircraft use collective thrust vectoring to maintain hover stability, then hover stability is improved, but transition complexity increases during VTOL to biplane transition
Solution Approach 1:
The flight control system dynamically adjusts thrust vector angles and rotor speeds based on the aircraft's flight regime. During hover, collective thrust vectoring maintains stability, while during transition, the system automatically coordinates differential thrust vectoring with wing rotation to simplify the overall transition procedure.
Solution Approach 2:
The flight control system uses feedback from sensors monitoring aircraft attitude, thrust vector angles, and rotor speeds to automatically coordinate the transition process. This feedback control simplifies the transition by eliminating the need for manual coordination of multiple 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
Enables efficient and stable transitions between VTOL and biplane orientations, improving hover stability and forward flight capabilities by optimizing thrust vectoring and pitch attitudes according to the aircraft's thrust-to-weight ratio.
Implementation Method 1
A plurality of propulsion assemblies are coupled to a common structure. The thrust array is operable to provide thrust for the aircraft.
Implementation Method 2
engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability followed by collectively reducing the thrust vector angles to initiate forward flight
Implementation Method 3
Fixed-wing aircraft, such as airplanes, are capable of flight using wings that generate lift responsive to the forward airspeed of the aircraft
Implementation Method 4
VTOL aircraft are capable of taking off, hovering and landing vertically. One example of VTOL aircraft is a helicopter which is a rotorcraft having one or more rotors that provide lift and thrust to the aircraft
Data Source
AI summary
An aircraft includes an airframe having first and second wings with first and second pylons extending therebetween and having a two-dimensional distributed thrust array of outboard propulsion assemblies attached thereto. A flight control system is coupled to the airframe and is operable to independently control a rotor speed and a thrust vector of each propulsion assembly. In a low thrust to weight configuration, transitions from the VTOL orientation to the biplane orientation include establishing a pitch down flight attitude while engaging in collective thrust vectoring of the outboard propulsion assemblies to maintain hover stability followed collectively reducing the thrust vector angles to initiate forward flight. In a high thrust to weight configuration, transitions from the VTOL orientation to the biplane orientation include maintaining a level flight attitude while collectively increasing the thrust vector angles of the outboard propulsion assemblies to initiate forward flight.