Aircraft Wing Lift Augmentation via Distributed Propeller Slipstream
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Solution Overview
Problem
Traditional blown lift aircraft face challenges in achieving steep descent angles and maintaining low-speed lateral-directional control authority due to mechanical complexity and inefficiency, particularly in gusty conditions, which limits their practical application.
Innovation Solution
The use of a distributed electric propulsion system with strategically selected propeller sizes, flap deflections, and aileron configurations to concentrate and deflect the propeller slipstream over the wing, enabling high lift augmentation with reduced thrust and drag, and enhancing low-speed lateral control through the use of slotted flaps and drooped ailerons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high power-settings are used by the propeller to achieve significant blown lift augmentation, then lift augmentation is improved, but descent angle becomes shallow and drag increases
Solution Approach 1:
The patent applies local quality by directing the propeller slipstream to specific regions of the wing rather than uniformly across the entire wing surface. The slipstream is concentrated over the central portion of the wing where it provides maximum lift augmentation, while the outboard regions receive less blowing. This localized application allows for reduced overall propeller power settings while maintaining sufficient lift, enabling steeper descent angles without the excessive drag that would result from high power settings across the entire wing span.
2Device complexity
If conventional unblown ailerons are used at low approach speeds, then lateral control is simplified, but control authority is reduced due to low dynamic pressure and high angle of attack
Solution Approach 1:
The patent uses the propeller slipstream as an intermediary to enhance aileron effectiveness. The high-velocity slipstream flows over the ailerons, increasing the dynamic pressure and airflow energy acting on these control surfaces. This intermediary airflow allows conventional aileron designs to generate sufficient rolling moments at low approach speeds where normal airflow would be insufficient, thereby maintaining lateral control authority without requiring complex blown aileron mechanisms.
3Force
If blown ailerons are integrated into highly deflected flaps to improve low-speed lateral control, then control authority is improved, but mechanical complexity increases significantly
Solution Approach 1:
The patent extracts the blowing function from the control surface integration by using the propeller slipstream as a separate, independent source of high-velocity airflow. Instead of integrating complex blown aileron mechanisms into the flap system, the invention allows the naturally occurring propeller slipstream to flow over the ailerons. This separation of the blowing function from the control surface mechanism maintains lateral control authority while avoiding the mechanical complexity of integrated blown control systems.
4Power
If turboprop engines are used for blown lift augmentation, then propulsion is achieved, but the number of engines is limited to four due to integration and maintenance complexity
Solution Approach 1:
The patent applies segmentation by dividing the propulsion system into multiple independent propeller units distributed along the wingspan rather than using a limited number of large turboprop engines. Each propeller can be independently controlled and optimized for specific wing sections. This segmented approach allows for greater flexibility in the number and size of propulsion units, facilitating the transition to electric propulsion systems where each propeller can be driven by independent electric motors, thereby avoiding the four-engine limitation of traditional turboprop configurations.
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 approach allows for steep descent capabilities without high drag-inducing flap deflections and improves low-speed lateral-directional control authority, simplifying the mechanical complexity of traditional solutions while maintaining efficient propulsion.
Implementation Method 1
the slipstream, or wake, from the propeller that interacts with the wing to cause lift
Implementation Method 2
blows air over the wing and causes the slipstream, or wake, from the propeller that interacts with the wing to cause lift
Implementation Method 3
concentrate and deflect the propeller slipstream over the wing, enabling high lift augmentation with reduced thrust and drag
Implementation Method 4
enhancing low-speed lateral control through the use of slotted flaps and drooped ailerons
Data Source
AI summary
A system and method for lift augmentation of an aircraft having a wing with a leading edge and a trailing edge extending along a wingspan, a plurality of thrust-producing devices connected to the bottom of said wing, at least one flap connected to an inboard portion of said wing proximate the trailing edge, and an aircraft roll control device connected to said wing, wherein the improvement comprises a plurality of slipstreams associated with a plurality of thrust producing devices and a flap adaptable to deflect from a chord of the inboard portion of the wing.