Tilt-Wing Thrust Control to Prevent Stall During Landing
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Solution Overview
Problem
Existing aircraft designs face challenges in taking off and landing on short runways or without runways, leading to wing stall due to reduced thrust and increased angle of attack during descent, especially when larger engines are used for additional lift, which increases weight and fuel consumption.
Innovation Solution
A control system for an aircraft with a tilt-wing that includes main and auxiliary propellers, where main propulsors provide maximum thrust and auxiliary propulsors adjust thrust variably, managed by a controller, to maintain optimal propeller slipstream and prevent wing stall during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If larger, more-powerful engines are used to increase thrust for short runway operations, then the aircraft's thrust capability is improved, but the aircraft weight increases and fuel consumption increases
Solution Approach 1:
The aircraft propulsion system is segmented into multiple independent engines (e.g., four engines on a tilt-wing aircraft) rather than using one or two large engines. This segmentation allows the total thrust requirement to be distributed across smaller engine units, reducing the weight penalty associated with oversized engines while maintaining the necessary thrust capability for short runway operations and vertical takeoff/landing.
2Use of energy by moving object
If engines are throttled down during inbound transition to reduce thrust, then fuel consumption is reduced, but the propeller slipstream velocity decreases and wing stall is more likely to occur
Solution Approach 1:
During inbound transition, instead of uniformly throttling down all engines, the system maintains excessive or partial thrust output from some engines while reducing others. This partial action approach ensures that sufficient propeller slipstream velocity is maintained over the wing to prevent stall, while still achieving some fuel savings by reducing thrust from non-critical engines.
Solution Approach 2:
The thrust management during inbound transition applies local quality by differentiating the thrust levels of individual engines based on their position and function. Engines positioned to provide critical slipstream over the wing maintain higher thrust, while other engines are throttled down, creating a non-uniform thrust distribution that prioritizes wing stall prevention in critical areas.
3Force
If the tilt-wing is positioned at a higher angle of attack during descent, then lift is improved for short runway landing, but the risk of wing stall increases
Solution Approach 1:
The system takes preliminary action by maintaining high engine thrust and strong propeller slipstream before the aircraft actually enters the high-angle-of-attack descent configuration. This preliminary generation of energetic slipstream flow prepares the wing with sufficient airflow energy to delay stall onset, allowing the aircraft to safely adopt higher angles of attack for improved lift during short runway landing.
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 system effectively prevents wing stall during descent by maintaining maximum thrust and propeller slipstream, allowing safe landing and takeoff on short or no runways, reducing drag and fuel consumption.
Implementation Method 1
lower thrust during the inbound transition causes a lower slipstream velocity to be applied to the tilt-wing
Implementation Method 2
The main propulsors are configured to provide a first maximum amount of thrust to the main propellers
Implementation Method 3
improving lift of the aircraft
Implementation Method 4
The effective angle of attack of the tilt-wing is determined by the combination of the velocity vector and the propeller slipstream vector
Implementation Method 5
The auxiliary propulsors are configured to provide a variable amount of thrust to the auxiliary propellers. The first maximum amount of thrust and the variable amount of thrust together provide an overall thrust to descend and land the aircraft
Data Source
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AI summary
An aircraft, a method of controlling the aircraft, and a control system (12) for the aircraft (10) has a fuselage (16) and tilt-wing (14) movable relative to the fuselage. A plurality of main propulsors coupled to main propellers (40) that is coupled to the tilt-wing, which are configured to provide a first maximum amount of thrust. A plurality of auxiliary propulsors coupled to auxiliary propellers (48) that are spaced apart from the tilt-wing, which are configured to provide a variable amount of thrust. A controller (72) signals the main propulsors to operate at the first maximum amount of thrust when the tilt-wing moves from the cruise position to the transition position, and signals the auxiliary propulsors to operate at the variable amount of thrust when the tilt-wing is in the transition position in which the first maximum amount of thrust and the variable amount of thrust together provide an overall thrust to descend and land the aircraft.