11.9 Flashcards
Give two examples of active load control
Manoeuvre load control
Gust load alleviation
What is gust load alleviation
Reduces the effect of gust loads. on the a/c by deflecting control surfaces
Accelerometer in the wing tips keep the bending constant by using ailerons.
What is manoeuvre load control.
Use wing control surfaces to mov the centre of lift inboard during manoeuvres such that the wing root bending moment is decreased.
With MLC activated, in response to a gust, the aileron is deflected to reduce the lift outboard and increase the lift inboard.
What are hydraulic flying power control units (PCUs)
What do PCUs do?
Single assembly
Position the flight control surface.
Provide protection against flutter
In dampening mode the unit is depressurised.
The bypas valve is a spring loaded pressure operated valve.
What s power assisted control.
What is follow up
Pilot still gets feedback, known as reversible controls.
In the event of hydraulic failure pilot can still operate.
Follow up is when the input lever is moved back to neutral. Follow up movement is always proportional to input movement.
Fly-by-wire
What is the main benefit
What are some of the components.
What do flight control computers do
Massive weight savings.
Rotary variable differential transformers (RVDTs) , screens, sensors, power drive units, artificial feel systems.
Stabilise the a/c without the crews involvement, prevent crew operating outside do the flight envelope, determine how much to move the actuators.
Fly by wire operation
Compressors sample data concerning flight conditions. E.g:
- Pitch, roll, yaw rate and linear accelerations.
- Angle of attack and side slip.
- airspeed, Mach number, pressure, altitude, stick and pedal demands.
- other cockpit demands.
Fly by wire stability
Three gyroscopes fitted with sensors to sense movement in the different axis.
Fly by wire moves a/c back on datum.
What is meant by a mode/law with reference to fly-by-wire.
A mode/law is a software that transforms movement of the stick into movement of the control surfaces.
Movement of the control surface depends on which mode the a/c is in.
What is the most basic form of artificial feel
Spring box
What is a more common type of artificial feel then spring box
A spring loaded roller that fits into the Valley of a V-shaped centring cam.
What is Mach trim and why is it important.
Trimming the a/c to prevent the nose down motion known as Mach tuck caused by the aft movement of the aerodynamic centre due to the formation of shockwaves.
Stall prevention / warning system
A stick shaker can be used to warn of imminent stall
A stick nudged can be used if the pilot keeps pulling on the stick.
Pitch attitude protection
Angle is displayed on artificial horizon
Some a/c will prevent you from pitching above a certain angle.
High angle of attack protection
What is AOA
AOA is the angle between oncoming air and a reference line on the a/c or wings.
Has priority over all other protection systems.
Protects against stall and wind sheer.
What is rigging
Adjustment + travel of the moveable flight control surfaces.
Involves cable tensioning, adjusting travel limits of controls and tabs, setting travel stops.
Newer a/c incorporate electronic controllers in the rigging process.
