primary flight controls Flashcards
what are the properties of the balance point?
the point which all the weight of the aircraft acts and is the point which the three axes - lateral, longitudinal and normal intersect.
what are the characteristics of the elevator? (3)
- located at the rear of the tail section
- controlled by forward and aft movement of control column in cockpit
- controls the aircraft in pitch around the lateral axis which run from the wingtip to wingtip.
what are the characteristics of the aileron? (3)
- located on the outboard trialling edges of the wing.
- controlled by left and right movement of the control column
- control the aircraft in a roll around the longitudinal axis, running from the nose to the tail.
what are the characteristics of the rudder? (3)
- located on the rear of the vertical stabiliser
- controlled by the left and right movement of the rudder pedals
- controls the aircraft in yaw around the normal (vertical) axis which runs vertically through aircraft CoG
what is the reaction when the pilot has eased back on the control column deflecting the elevator up?
airflow travelling over the elevator is deflected upwards, and the reaction is a force pushing the tail of the aircraft downwards.
what is the reaction when the pilot has moved the control column to the left deflecting the left aileron upwards?
what happens with the right-wing?
what is the result?
airflow travelling over the left aileron is deflected upwards, the reaction is a force pushing the left-wing downwards.
The right aileron moves downwards, which pushes the air downwards. the reaction is that the wing moves upwards.
results in aircraft rolling left
what is the reaction when the pilot has depressed the left rudder pedal deflecting the rudder to the left?
airflow travelling around the rudder is deflected to the left and the reaction is to push the tail to the right causing nose of the aircraft to yaw.
the reaction of all forces is caused by what?
newtons third law - for every action there’s an equal and opposite reaction.
what are the primary effects of elevator, aileron and rudder movement?
Elevator - pitch up/down
Roll - left/right
yaw - left/right
what are the secondary effects of the elevator?
none, except change of airspeed
what are the secondary effects of the aileron? (4)
slip, yaw, spiral descent
- aircraft will slip into turn
- airflow will strike the tail at an angle
- aircraft will try to re-align with this airflow
- re-alignment causes aircraft to yaw
what are the secondary effects of the rudder? (4)
skid, roll, spiral descent
- aircraft will skid out of the turn
- one wing will travel a greater distance in the same time, making it travel faster
- more lift is produced on this wing
- aircraft will roll
how does airspeed affect control surfaces?
more airspeed = more air that will pass over the control surfaces = more air deflecting = greater resultant force.
at low airspeeds what happens to control surfaces?
- controls are lighter, less effective
- more deflection is required for the desired result
at high airspeeds what happens to control surfaces?
- control are heavier, more effective
- less deflection required for desired result
what is slipstream, what is it caused by and increasing the amount of it does what?
the corkscrew motion of air travelling backwards and around the fuselage of an aircraft.
caused by the rotation of the propellor.
increases the flow of air over the elevator and rudder and so make those controls more effective.
what does increasing power do to control surfaces? and what should you do when doing it? (3)
- nose pitches up due to increased thrust
- nose yaws left (if the propellor rotates clockwise) due to increased slipstream striking the tail
- ease forward on the control column slightly and apply the right rudder.
what does decreasing power do to control surfaces? and what should you do when doing it? (3)
- nose pitches down due to a decrease in thrust
- nose yaws to the right due to reduced slipstream striking the tail
- ease back slightly on the control column and apply left rudder.
what is the use of trim tabs and why are they important.
used to reduce manual energy and work required to stabilise an aircraft during flight.
without trim tabs, pilots are forced to hold the controls with greater force.
where can trim tabs be located?
elevator, ailer, and rudder but the primary being on the elevator.
what does the elevator trim do?
relives the pilot of control pressures and works in the natural sense of if you’re having to hold back on the controls to prevent nose drop, you trim wheel backwards.
where are fixed trim tabs usually found and what are they used for?
trailing edge of the rudder
compensate for propellor slipstream which would otherwise cause an aircraft to yaw and roll instead of flying straight and level.
what are the methods for obtaining aerodynamic balance?
- hydraulic for powered controls and by using some form of aerodynamic balance for smaller aircraft.
involves using tabs to alter the airflow over the control surface that reduces or increases the effort required to deflect the controls.
what are the two types of tabs used?
balance and anti-balance tabs
