Retractable Duct Channel Wing Drag Reduction
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Solution Overview
Problem
Aircraft with channel wings and ducted propellers face increased drag at high speeds, reducing efficiency, as the full duct provides more drag than thrust benefit above 60 MPH, necessitating a solution to maximize thrust during takeoff and minimize drag during cruise.
Innovation Solution
A retractable duct system for channel wings and canards that retracts into a lower semi-circular shape, allowing for short takeoff distances and vertical takeoff while reducing drag at high speeds by using a duct with small propeller tip clearance and a mechanical system for deployment and retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a full duct is used around the propeller, then thrust is increased by up to 50%, but aerodynamic drag increases above 60 MPH reducing overall speed
Solution Approach 1:
The duct is designed to be retractable rather than fixed, allowing it to change position dynamically based on flight conditions. The duct can be extended during takeoff to maximize thrust and retracted during cruise to minimize drag, making the system adaptive to different operational regimes
Solution Approach 2:
The duct is divided into two separate sections: a fixed lower semi-circular portion and a movable upper portion. This segmentation allows the upper duct to be retracted independently while the lower duct remains in place, enabling drag reduction without completely removing the thrust-enhancing structure
2Speed
If a full duct is extended during takeoff, then vertical liftoff and short takeoff distances are achieved, but drag increases during high speed cruise flight
Solution Approach 1:
The upper duct portion is designed to move between extended and retracted positions based on flight phase. During takeoff, it extends to provide thrust enhancement; during cruise, it retracts to reduce drag, creating a dynamic system that optimizes performance for each flight regime
Solution Approach 2:
The duct extension is prepared and positioned before takeoff to ensure maximum thrust is available when needed. The system is pre-configured for vertical liftoff capability, and the retraction is timed to occur as the aircraft transitions to cruise speed, preventing drag from limiting high-speed performance
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 retractable duct system enhances thrust by up to 50% during takeoff and reduces drag during cruise, enabling efficient short takeoff and high-speed flight by optimizing propeller efficiency and aerodynamics.
Implementation Method 1
The small tip clearance increases the thrust by reducing induced drag on the propeller and increasing the propeller's efficiency
Implementation Method 2
above an airspeed of approximately 60 MPH, the aerodynamic drag from the duct is greater than the increase in thrust provided by the duct
Data Source
AI summary
An embodiment of the invention provides a method where retractable ducts or shrouds are extended over propeller(s) that are fixed in wing channels on an aircraft during takeoff and landing to increase flight safety and efficiency. Fully extending the duct or shroud during takeoff increases lift and upward thrust, while retracting the duct or shroud and stowing the duct or shroud inside of the wing during forward cruise decreases aircraft drag and increases lift. Duct or shroud extension during takeoff also enables critical safety and noise cancellation functionality. The method provided for safe and efficient takeoff can be applied in reverse order for safe and efficient landing.