Dual Rotor Shrouded Thrust Unit for Drag Reduction
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Solution Overview
Problem
Conventional multirotor aircraft thrust producing units with ducts or shrouds are inefficient in transversal air flow conditions due to increased drag, weight, and limited adaptability, as they are optimized for axial air flow and cannot be inclined to adjust thrust vectors effectively during forward flight.
Innovation Solution
A thrust producing unit with at least two rotor assemblies and a shrouding that accommodates one of the assemblies, allowing for reduced drag and weight while maintaining efficiency in axial air flow conditions, and providing additional lifting and noise reduction benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a shrouding is provided around a rotor assembly to improve aerodynamic efficiency in axial air flow conditions, then thrust production in hover and axial flight is improved, but drag increases significantly in transversal air flow conditions during forward flight
Solution Approach 1:
The rotor system is divided into multiple independent rotor assemblies (e.g., two or more rotors on the same mast), allowing selective shrouding of individual assemblies rather than enclosing all rotors in a single large shroud. This segmentation reduces the overall frontal area and drag in transversal flow while maintaining aerodynamic benefits for shrouded rotors in axial flow conditions.
Solution Approach 2:
The inclination of rotor assemblies can be dynamically adjusted during flight operations. Rotor assemblies are configured to be inclinable relative to the mast axis, allowing the system to optimize thrust vectoring for different flight phases (hover, forward flight, transition) and reduce the negative impact of shroudings in transversal flow conditions.
2Power
If a shrouding is provided around rotor assemblies to enhance aerodynamic performance, then efficiency in axial air flow is improved, but the overall weight of the thrust producing unit increases
Solution Approach 1:
Instead of providing a single large shroud enclosing multiple rotor assemblies, the invention selectively shrouds only certain rotor assemblies (e.g., one or two out of multiple). This reduces the total amount of shroud material required, thereby lowering the overall weight while preserving aerodynamic benefits for the shrouded assemblies.
Solution Approach 2:
The shrouding is applied locally to specific rotor assemblies rather than uniformly to all rotors. This allows optimization of aerodynamic performance at critical locations (e.g., main thrust-producing rotors) while minimizing the weight penalty associated with extensive shrouding structures.
3Power
If conventional thrust producing units with shrouds are used, then aerodynamic efficiency is improved in axial flow, but adaptability to different flight conditions (especially forward flight) is limited
Solution Approach 1:
The rotor assemblies are configured to be inclinable relative to the mast axis, enabling dynamic adjustment of thrust vectoring angles. This allows the system to adapt to different flight conditions (hover, forward flight, transition phases) by optimizing the inclination of individual rotor assemblies, thereby overcoming the limitation of fixed-orientation shrouded rotors.
Solution Approach 2:
Multiple independent rotor assemblies with selective shrouding and individual inclination capabilities provide enhanced adaptability. Each rotor assembly can be independently controlled and inclined, allowing the system to optimize performance for various flight phases and maneuvering requirements, significantly improving versatility compared to conventional single-shroud designs.
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 solution significantly reduces drag in transversal air flow conditions, lowers overall weight, and maintains performance in axial air flow conditions, enhancing aerodynamics and safety by allowing for reduced power consumption and noise emission.
Implementation Method 1
at least two rotor assemblies (7d, 8d) which define separated rotor planes (21, 22)
Implementation Method 2
The shrouding accommodates one of the assemblies, allowing for reduced drag and weight
Implementation Method 3
thrust producing unit for producing thrust in a predetermined direction
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention is related to a thrust producing unit 3d for producing thrust in a predetermined direction 23, comprising at least two rotor assemblies 7d, 8d and a shrouding 6d, each one of the at least two rotor assemblies 7d, 8d defining an associated rotor plane 21, 22, wherein a first rotor assembly 7d of the at least two rotor assemblies 7d, 8d is provided for operating in a failure-free operating mode of the thrust producing unit 3d and a second rotor assembly 8d of the at least two rotor assemblies 7d, 8d is provided for operating at least in case of a failure of the first rotor assembly 7d, and wherein the shrouding 6d accommodates at most one of the at least two rotor assemblies 7d, 8d.