Flight control systems Flashcards
What are the 4 fundamental forces acting on an aircraft during flight
Lift, drag, weight and thrust
How does the aircraft move in different directions?
By changing the balance of these forces
What are the 6 fundamental ways an aircraft can move in?
Move linearly:- in a longitudinal direction in a lateral direction in a vertical direction Rotate:- in pitch about its lateral axis in roll about its longitudinal axis in yaw about its vertical axis
What controls does a pilot use to control the aircraft?
elevator, ailerons, rudder or throttle
How Does an Aerofoil Produce an Aerodynamic Force?
Air sticks to surface due to its viscosity
Air must curve more to pass over upper surface of aerofoil than lower surface
Centripetal force needed to make air move in this curved path
Difference in static pressures between two aerofoil surfaces creates a force perpendicular to aerofoil - e.g. lift force produced by aircraft wing
Force produced is a function of pressure difference
How is the centripetal force provided?
Provided by a pressure gradient perpendicular to direction of flow
Free stream stagnation pressure Po is constant
Static pressure P near surface reduces
Bernoulli:- as static pressure reduces , velocity increases
What is pressure difference a function of?
Pressure difference is a function of:
Camber (curvature) of aerofoil
Angle of attack to approaching airflow
Speed & density of the airflow
What is the purpose of the horizontal tail plane?
To produce an upward or downward force as required to enhance aircraft longitudinal stability in steady state or wind gust conditions
Pushing/pulling of control column or Forward/backward movement of side-stick results in what?
Elevator moves up or down Changes tail plane camber Changes magnitude/direction of force Rotates aircraft about its lateral axis Changes aircraft pitch attitude
What is the purpose of an All-Moving Horizontal Tail plane
Mainly used for high speed combat aircraft to enhance manoeuvrability
Pitch control achieved by rotating entire horizontal tailplane about a pivot
Varies its angle of attack to local airflow
Generates different amounts of upwards or downwards force
How does a Canard Foreplane control pitch
By a moving foreplane ahead of main wing rather than by an elevator behind main wing
What are the advantages and disadvantages of the canard foreplane?
Main advantage: Elevator trims aircraft by downward lift Subtracts from lift sum Canard trims aircraft by upward lift Adds to lift sum Main Disadvantage: Canards have more stability/control & stall issues than conventional tail plane
What does Rotation of control column or Sideways movement of sidestick result in?
Ailerons on each wing move differentially, one goes up & one goes down
When the Ailerons on each wing move differentially, How does this affect the aircraft?
Change in local wing camber due to aileron position:
Difference in lift between two wings
Resultant rolling moment about aircraft longitudinal axis
How does Pressing left or right rudder pedal affect the aircraft?
Rudder on tail fin moves sideways
Changes camber of tailfin vertical aerofoil
Provides sideways force
Rotates aircraft about its yaw axis
What does the engine thrust do?
Provides runway acceleration to lift-off speed and counteracts aircraft aerodynamic drag
What regulates the engine airflow in a carburetted engine
The throttle lever
What regulates the engine fuel flow in an injection engine
The power lever
What is the purpose of Full Authority Digital Engine Control (FADEC) Systems
Execute commands from cockpit thrust/power levers or auto-thrust systems
Control fuel flow into combustion chamber
Control other variable devices that moderate core airflow
Monitor numerous engine parameter
Numerous engine parameters are monitored for what reason?
Temperature & shaft speed limits are not exceeded
Spool acceleration rates do not push compressor into damaging surge conditions
How does an aircraft propulsion system generate thrust
By forcing a quantity of air rearwards (generally) so that it can fly forwards.
What can Vectoring & varying propulsion system thrust also be used for?
To control aircraft in-flight manoeuvres
To take-off or land vertically
