Powered High-Lift Biplane Wing for STOL Aircraft
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Solution Overview
Problem
Conventional high-lift systems for STOL aircraft face limitations in achieving high lift forces at low speeds due to low dynamic pressure, and existing propulsion systems have inefficiencies at low flying speeds, making it difficult to control flight and achieve competitive cruising speeds.
Innovation Solution
An active high-lift system utilizing a biplane wing configuration with motorized propulsion elements positioned above the main lift surface and a hinged flow control element on the secondary lift surface, which immerses the secondary lift surface within the propeller wake, enhancing lift through controlled aerodynamic flow and Coandaeffect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rotor blades are used for short and vertical take-off and landing, then vertical lift capability is achieved, but cruising speed is limited by blade tip speed
Solution Approach 1:
The aircraft system is segmented into two distinct functional components: a conventional propeller for forward thrust and propulsion, and a separate rotor blade assembly for vertical lift generation. This segmentation allows each component to optimize its performance independently - the propeller achieves high cruising speeds while the rotor provides vertical take-off and landing capability without being constrained by tip speed limitations during forward flight
Solution Approach 2:
The rotor blade assembly is designed with dynamic control mechanisms including variable pitch angles and adjustable rotational speed. The rotor can be deployed and activated specifically during vertical take-off and landing operations, then retracted or deactivated during conventional forward flight, allowing the system to adapt its configuration based on operational requirements and eliminate the compromise between vertical lift and cruising speed
2Force
If propulsion elements are placed on the leading edge of the wing, then forced circulation and lift are increased, but propulsion efficiency at low flying speeds decreases due to high wake air speed requirements
Solution Approach 1:
A ducted fan system serves as an intermediary mechanism between the propulsion element and the wing surface. The ducted fan directs and controls the airflow more efficiently, creating the necessary forced circulation and lift enhancement while operating at lower rotational speeds compared to direct propeller configurations. This intermediary structure allows effective low-speed lift generation without requiring excessively high wake air speeds that would consume excessive power
3Ease of operation
If large-diameter propellers are used with propulsion plane on trailing edge, then lift control is improved, but loss appears in leading edge region when angle of attack increases
Solution Approach 1:
The invention transitions from a single-plane propeller configuration to a three-dimensional rotor blade assembly positioned above the wing. This vertical dimension allows the rotor to generate lift independently of the wing's angle of attack, preventing leading edge flow separation and loss. The rotor operates in a different spatial plane, creating a vertical airflow component that supplements horizontal wing lift without being constrained by wing incidence angle limitations
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 allows for high lift levels and independent control of thrust and lift, enabling flights at low speeds with high angles of attack and achieving competitive cruising speeds, significantly reducing take-off distances and times compared to conventional aircraft.
Implementation Method 1
a propulsion element situated above the upper surface or extrados of a wing accelerates the air upstream of its position, so that the static pressure above the wing surface in this zone decreases and the lift in this wing zone increases
Implementation Method 2
a hinged flow control element on the trailing edge of the secondary lift surface and designed to rotate around a hinging axis situated along the direction of the wingspan of the secondary lift surface
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Active high-lift system for short take-off and landing aircraft which comprises: - a biplane wing which comprises a main lift surface (1) and a secondary lift surface (2), where: • the extrados (1.3) of the main lift surface (1) is arranged facing the intrados (2.4) of the secondary lift surface (2), • the main lift surface (1) comprises a high-lift device (1.2.2) on the trailing edge (1.2) which comprises a surface curved towards the intrados (1.4), • the secondary lift surface (2) comprises a hinged flow control element (2.2.1) on the trailing edge (2.2) which is adapted to rotate about an axis, - one or more motorized propulsion elements (6, 10) situated above the extrados (1.3) of the main lift surface (1), upstream of the leading edge of the secondary lift surface (2) so that the secondary lift surface (2) is configured to be immersed within the wake of the propellers (10).