Stowable High-Lift Propellers for Aircraft Lift Enhancement
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Solution Overview
Problem
Conventional aircraft designs face challenges in achieving high lift coefficients for short takeoff and landing distances, particularly in constrained spaces like urban areas, due to limitations in wing loading and maximum lift coefficients from mechanical high-lift devices.
Innovation Solution
Integration of stowable high-lift propellers with a leading-edge assembly, such as a Krueger flap or slat, which deploys to increase airflow over the wing, enhancing lift by creating a high-speed air jet for low-speed operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If mechanical high-lift devices (trailing edge flaps, leading edge slats) are used to increase maximum lift coefficient, then the lift coefficient can be increased to Cimax 3.5, but the takeoff and landing distances remain too long for urban areas and the wing loading cannot be sufficiently increased
Solution Approach 1:
The patent combines propulsion function and high-lift function into a single integrated system. The propellers are mounted on the wing and serve dual purposes: providing thrust for cruise flight and generating high-speed air jets for lift enhancement during takeoff and landing. This merging eliminates the need for separate mechanical high-lift devices and enables much higher lift coefficients (Cimax > 5.0) than conventional mechanical devices (Cimax 3.5).
Solution Approach 2:
The propellers are designed to perform multiple functions across different flight phases. During cruise, they provide thrust. During takeoff and landing, they generate high-speed air jets that flow over the wing to create enhanced lift. This multi-functionality allows a single system to replace both propulsion systems and mechanical high-lift devices, enabling operation from short urban runways while maintaining cruise efficiency.
2Speed
If the wing area is increased to reduce takeoff and landing speed, then the slowest airspeed decreases allowing shorter runway, but the wing becomes larger and heavier increasing aircraft weight
Solution Approach 1:
The patent changes the physical parameters of the airflow over the wing by introducing high-speed jets from propellers. This increases the dynamic pressure and lift coefficient without changing the wing's physical dimensions. The lift equation L = 1/2 * ρ * V² * S * CL shows that by dramatically increasing V (airflow speed) through propeller jets, high lift can be achieved with the same wing area S, avoiding the need to increase wing size and weight.
3Force
If a jet of high-speed air is placed over the wing to increase lift at low speed, then the lift coefficient can be dramatically increased by the square of the speed ratio, but additional propulsion systems and control mechanisms are required increasing device complexity
Solution Approach 1:
The patent merges the propulsion system and high-lift system into a single integrated propeller-wing assembly. The propellers that provide cruise thrust are the same propellers that generate high-speed air jets for lift enhancement. This eliminates the need for separate propulsion systems and complex control mechanisms, reducing overall device complexity while achieving dramatically increased lift coefficients (Cimax > 5.0).
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 solution significantly reduces ground roll requirements for takeoff and landing, allowing aircraft to operate from short runways and increasing the maximum lift coefficient, enabling steeper climbs and descents while maintaining cruise efficiency.
Implementation Method 1
placing the wing in a jet of air moving significantly faster than the aircraft itself would allow high lift to be generated at low speed
Implementation Method 2
The lift of an airfoil/wing is strongly dependent on speed (Lift Equation, supra) that placing the wing in a jet of air moving significantly faster than the aircraft itself would allow high lift to be generated at low speed
Implementation Method 3
Researchers realized early in the history of aviation (pre WW2) that since the lift of an airfoil/wing is strongly dependent on speed
Data Source
AI summary
Systems and methods for increasing lift of an aircraft lifting surface, may include: a leading-edge assembly; a plurality of high-lift propellers, coupled to the slat assembly and configured to be stowed within a compartment of the lifting surface; a high-lift motor to provide motive force to at least one of the plurality of the high-lift propellers; and a deployment linkage configured to move the slat assembly and plurality of high-lift propellers between a deployed configuration and a stowed configuration, wherein in the stowed configuration the high-lift propellers are stowed within the compartment of the lifting surface and at least a portion of the slat assembly covers the compartment of the lifting surface, and in the deployed configuration the high-lift propellers are positioned external to the aircraft lifting surface to direct airflow from the high-lift propellers past the leading-edge assembly.