Tilted Distributed Propellers for Faster VTOL Control Response
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Solution Overview
Problem
Conventional distributed propulsion systems in VTOL aircraft face challenges with control authority and lag due to rotational inertia, particularly in medium and large aircraft, where excessive power margins or cyclic and collective controls are needed to achieve safe flight, undermining the benefits of distributed propulsion.
Innovation Solution
The implementation of a distributed propulsion system with propellers symmetrically arranged around the aircraft's center of gravity, each rotating within a tilted plane, allowing for equal thrust magnitude and zero horizontal force or torque summation, enabling control of aircraft movement without rolling or pitching, thereby enhancing control authority and reducing lag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If propellers are mounted in the same plane or parallel planes with vertical thrust vectors, then the aircraft structure is simplified and lift is efficiently generated, but the aircraft experiences unacceptable control lag and insufficient control authority due to rotational inertia
Solution Approach 1:
The patent applies asymmetry by tilting the propeller planes at specific angles relative to the vertical axis. This asymmetric configuration allows the thrust vectors to have both vertical and horizontal components, enabling direct lateral and longitudinal control without requiring the aircraft to roll or pitch first, thereby overcoming the control lag problem while maintaining structural simplicity
2Ease of operation
If excessive power margin and cyclic and collective controls are added to distributed propulsion systems, then control authority is enhanced, but the benefits of distributed propulsion (coast, weight reduction, and safety) are eliminated
Solution Approach 1:
The patent transitions from a two-dimensional control problem (controlling thrust magnitude only) to a three-dimensional solution by tilting the propeller planes. This dimensional change allows direct control of lateral and longitudinal motion through the horizontal components of thrust vectors, eliminating the need for complex cyclic and collective control mechanisms while preserving the weight and safety benefits of distributed propulsion
3Ease of operation
If the aircraft rolls or pitches to achieve lateral or longitudinal motion in conventional configurations, then control is possible, but the rotational inertia causes unacceptable lag in response to control commands
Solution Approach 1:
The patent implements preliminary action by pre-tilting the propeller planes at specific angles before flight operations. This pre-configured geometry ensures that when thrust is applied, the horizontal components are immediately available to produce lateral and longitudinal motion without the time delay associated with rolling or pitching maneuvers, thus eliminating control lag
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 provides greater control authority and reduced control lag compared to non-tilted systems, allowing for efficient lateral, longitudinal, and directional movements without the need for excessive power margins or complex control mechanisms.
Implementation Method 1
each propeller has a rotation direction within a tilted plane of rotation, and a summation of horizontal force vectors created by the tilted plane of rotation of all the propellers is substantially zero when all the propellers are creating a substantially equal thrust magnitude
Implementation Method 2
Movement of the aircraft is controlled by selectively increasing or decreasing a thrust of at least one of the two or more propellers
Data Source
AI summary
An aircraft comprises a fuselage, one or more support structures connected to the fuselage, one or more engines or motors disposed within or attached to the one or more support structures or the fuselage, and a distributed propulsion system. The distributed propulsion system comprising two or more propellers symmetrically distributed in an array along the one or more support structures with respect to a center of gravity of the aircraft and operably connected to the one or more engines or motors, wherein each propeller has a rotation direction within a tilted plane of rotation, and a summation of horizontal force vectors created by the tilted plane of rotation of all the propellers is substantially zero when all the propellers are creating a substantially equal thrust magnitude. Movement of the aircraft is controlled by selectively increasing or decreasing a thrust of at least one of the two or more propellers.