Retractable Stacked Propeller Mast for Low-Drag VTOL Flight
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Solution Overview
Problem
Existing VTOL aircraft face inefficiencies in both vertical takeoff and landing due to separate non-articulating rotors or complex tilting propulsors, leading to increased weight, drag, and design complexity, while helicopters optimize hover efficiency at the cost of cruise efficiency.
Innovation Solution
A VTOL aircraft design featuring stacked propellers that transition from vertical takeoff and landing to cruise mode by deploying propellers on wingtips, wings, or the fuselage, with co-rotating blades that adjust pitch and speed to reduce drag and noise, and retract during forward flight, allowing for efficient lift and thrust generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate non-articulating rotors are used for vertical lift and forward thrust, then the aircraft can provide vertical lift during forward flight, but this results in extra motor weight and increased aircraft drag
Solution Approach 1:
The patent applies universality by designing a single set of rotors that can perform multiple functions: providing vertical lift during hover and forward thrust during forward flight. The rotors are articulated to tilt between vertical and horizontal positions, allowing the same rotor system to replace what would traditionally require separate rotor systems for different flight phases, thereby reducing overall motor weight.
Solution Approach 2:
The patent applies dynamics by making the rotors articulated and capable of tilting between different orientations. The rotor assembly can dynamically adjust its angle - vertical for hover mode and horizontal for forward flight mode - allowing the system to adapt its configuration based on flight phase, eliminating the need for fixed non-articulating rotors that would add unnecessary weight.
2Reliability
If separate non-articulating rotors are used for vertical lift and forward thrust, then the aircraft can maintain vertical lift, but this results in increased aircraft drag
Solution Approach 1:
The articulated rotor system dynamically adjusts its orientation to match flight requirements. During forward flight, the rotors tilt horizontally to provide thrust aligned with the direction of motion, minimizing drag. During hover, they tilt vertically to provide lift. This dynamic reconfiguration eliminates the drag penalty associated with fixed non-articulating rotors that would remain in suboptimal positions during forward flight.
Solution Approach 2:
The universal rotor system performs both vertical lift and forward thrust functions, eliminating the need for separate rotor systems that would each contribute to drag. The single articulated rotor system optimizes its configuration for each flight phase, reducing overall aircraft drag compared to a system with separate dedicated rotors.
3Weight of moving object
If distributed tilting propulsors are used to provide both vertical lift and forward thrust, then motor weight and aircraft drag are reduced, but this results in increased design complexity with six to twelve tilting rotors required
Solution Approach 1:
The patent applies segmentation by dividing the aircraft into modular sections, each equipped with its own articulated rotor assembly. The aircraft is segmented into multiple stations along the fuselage, with rotors distributed at these stations. This modular segmentation allows for reduced complexity at each station while maintaining overall system effectiveness, avoiding the need for a large number of tilting rotors concentrated in one complex assembly.
Solution Approach 2:
The patent applies dimensionality change by transitioning from a concentrated configuration of multiple tilting rotors to a distributed linear arrangement along the fuselage. This spatial redistribution along the longitudinal dimension of the aircraft reduces the complexity at any single location while maintaining the necessary lift and thrust capabilities through the coordinated operation of distributed rotor assemblies.
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 enables efficient vertical takeoff and landing while minimizing drag and noise during cruise, improving overall efficiency and reducing the complexity of the aircraft design by utilizing stacked propellers that adapt to different flight modes.
Implementation Method 1
During vertical ascent of the aircraft, stacked propellers are deployed to provide lift to the aircraft
Implementation Method 2
The first propeller and the second propeller co-rotate about a central axis of rotation
Data Source
AI summary
An aircraft can include a stacked propeller to generate lift during assent and descent. The stacked propeller includes a first propeller and a second propeller that co-rotate about an axis of rotation. In one embodiment, the blades are coupled to a rotor mast that contains an internal cavity. In one mode of operation, the first propeller and/or the second propeller can be stored in the internal cavity in order to reduce drag during flight. The aircraft can include one or more stacked propellers, such as a port propeller and a starboard propeller, which rotate in opposite directions during one or more modes of flight.