Aircraft Avionics Slip Maneuver for Idle Descent Speed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During an idle descent, aircraft may encounter over-speed conditions, which are currently addressed by deploying speed brakes or increasing thrust, both of which consume additional fuel and are undesirable, as they negate the fuel-saving benefits of the idle descent.
Innovation Solution
The aircraft avionics, such as the Flight Management System and Flight Guidance System, automatically execute a slip maneuver by adjusting control surfaces to increase aerodynamic drag and reduce airspeed, rather than using thrust or pitch, thereby maintaining fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If speed brakes are deployed to reduce airspeed during idle descent, then airspeed is reduced, but fuel efficiency is compromised and noise increases
Solution Approach 1:
The system changes the aircraft's aerodynamic parameters by initiating a slip maneuver, which alters the airflow relative to the wings and increases drag without mechanical braking. This transforms the airspeed control problem from a mechanical intervention (speed brakes) to an aerodynamic parameter change (slip angle), resolving the contradiction between speed reduction and fuel efficiency
Solution Approach 2:
The patent replaces the mechanical speed brake system with an aerodynamic slip maneuver controlled by flight guidance system. Instead of using mechanical brakes that create noise and fuel penalty, the system uses aerodynamic forces through coordinated rudder and aileron inputs to achieve speed reduction while maintaining fuel efficiency
2Speed
If pitch input is applied to reduce airspeed during idle descent, then airspeed is reduced, but additional fuel is consumed
Solution Approach 1:
The system changes from pitch parameter control to slip angle parameter control. By adjusting the slip maneuver parameters (rudder and aileron inputs) rather than pitch attitude, the system achieves airspeed reduction through increased aerodynamic drag without the fuel penalty associated with pitch-based speed control during idle descent
3Speed
If engine throttle is increased above idle to prevent over-speed condition, then airspeed is controlled, but fuel efficiency is reduced
Solution Approach 1:
The patent replaces thrust-based speed control with aerodynamic drag-based speed control. Instead of modulating engine throttle to control airspeed, the system uses slip maneuver-induced aerodynamic drag, eliminating the need to increase thrust above idle and thereby maintaining fuel efficiency while achieving precise airspeed control
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 slip maneuver effectively reduces airspeed without consuming additional fuel, maintaining the fuel-saving benefits of the idle descent while addressing over-speed conditions, and is implemented through the FMS & FGS by repeatedly monitoring airspeed and activating control surface adjustments.
Implementation Method 1
The aircraft enters a slip maneuver to increase aerodynamic drag and reduce airspeed
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method of controlling the flight of an aircraft 10 by automatically controlling the descent phase of an aircraft 10 using a Flight Management System and Flight Guidance System (FMS & FGS) 100 to control the air speed of the aircraft and respond to an over speed condition.