Aircraft Drag Device Positioning for Steep Approach Control
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Solution Overview
Problem
Aircraft face challenges in achieving steep descent at low speeds while maintaining good handling qualities, as drag devices like spoilers reduce lift and stall margins, potentially leading to high touch down sink rates and tail strikes, and existing solutions often require increased airspeed or result in landing weight limitations.
Innovation Solution
The system dynamically adjusts the position of drag devices based on estimated aircraft weight, measured flight path angle, and pilot input to optimize drag for steep approaches, automatically retracting devices when necessary to maintain stall speeds and maneuvering capability, thereby reducing the need for increased airspeed and minimizing landing weight limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If drag devices such as spoilers are deployed to increase descent ratio and trajectory angle, then maximum descent capability is improved, but stall margins are reduced and speed margins are compromised
Solution Approach 1:
The patent implements dynamic control of spoiler deployment based on real-time flight conditions including airspeed, altitude, and trajectory angle. The control system continuously adjusts spoiler position to maintain optimal descent ratio while preventing stall conditions, transforming the static spoiler deployment into a dynamic adaptive system that responds to changing flight parameters
Solution Approach 2:
The patent employs feedback control mechanisms where the flight control system monitors actual flight trajectory, airspeed, and angle of attack, then adjusts spoiler deployment accordingly. This closed-loop control ensures that descent ratio improvements do not compromise stall margins, as the system automatically reduces spoiler deflection when approaching stall conditions
2Reliability
If approach airspeed is increased to regain stall margins, then flying qualities are improved, but landing performance deteriorates due to increased landing distance and touch down sink rate
Solution Approach 1:
The patent changes the control parameter from fixed spoiler bias position to dynamically adjusted spoiler position based on trajectory angle and flight conditions. This allows the system to achieve steep approach trajectories without requiring increased approach airspeed, thereby maintaining both stall margins and landing performance
3Speed
If spoiler bias position is increased to enable steeper glide slope, then descent capability is improved, but maximum landing weight is limited
Solution Approach 1:
The patent transforms the static spoiler bias position into a dynamic control parameter that adapts to aircraft weight and trajectory requirements. The control system calculates optimal spoiler position based on current weight, desired glide slope, and flight phase, allowing heavy aircraft to achieve steep approaches without fixed bias 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 approach enables safer and more efficient steep approaches and landings with higher payload capacity, reducing air traffic and noise, and allows for operation without increasing approach airspeed, thus improving aircraft performance and environmental impact.
Implementation Method 1
drag devices such as flight spoilers are capable of increasing the maximum descent ratio by increasing the trajectory angle
Implementation Method 2
The spoiler creates a carefully controlled stall over the portion of the wing around it, greatly reducing the lift of that wing section
Data Source
Figure 1~1-1
Figure 1A
Figure 2
AI summary
A flight control system can achieve a relatively steep descent at relatively low speeds while retaining good airplane handling qualities from the pilot's point of view. The system and method optimize the drag device's positioning used so as to improve steep approach performance.