PHAK Ch 6 (Flight Controls) Flashcards
Primary Flight Control Systems
Ailerons, Elevator (or Stabilator, NOT CESSNA 172!!!!), Rudder
Things REQUIRED to control the airplane
Secondary Flight Controls
Flaps, Leading Edge Devices, Spoilers, Trim Systems
IMPROVE PERFORMANCE
Effectiveness of Control Surfaces
Require smooth airflow to be effective, will feel sluggish at slow speeds. Controls firmer and more rapidly responsive at higher airspeeds.
How do the Primary Flight Control Surfaces work?
Changes the airflow and the pressure distribution over and around the airfoil. These changes affect the lift and drag produced by the airfoil/allows a pilot to control the aircraft about its three axis’ of rotation.
What is the use of control stop mechanisms?
Flight controls may be limited to prevent the pilot from inadvertently over controlling and over stressing the aircraft during normal procedures.
Ailerons (Overview)
Ailerons control roll on the longitudinal axis. They move in the opposite direction form each other. Connected via cables, and pulleys.
How it Works: Controlled Falling
Right Turn: Turn the Yoke to the Right
The Aileron Deflecting to the Right LIFTS!! **OUT OF AIRFLOW* Reducing Lift, Wing Falls in that Direction
The other Aileron DROPS INTO AIRFLOW CREATING LIFT!!!, Wing LIFTS in Pushing the Aircraft to the Right.
Adverse Yaw
The DOWNWARD DEFLECTED AILERON produces more lift… this increase drag… slows the plane down a bit…. And pulls the nose of the plane towards the DOWNWARD Aileron and OPPOSITE of the Turn.
Adverse Yaw is caused by a result of differential drag and the difference of velocity between the two wings GREATER at Slower Airspeeds (more control input to maneuver, thus increase in adverse yaw) the aircraft
RUDDER is used to counteract the effect.
Ailerons (CESSNA 172S)
Differential Ailerons: One aileron is raised a greater distance than the other aileron is lowered. This produces an increase in drag on the descending wing (RAISING AILERON) (the direction of the turn) reduces adverse yaw.
Frise-Type Ailerons (These Are Only Characteristics): FREES AIR TO MOVE the aileron that RAISES pivots on an Offset Hinge, The LEADING EDGE of the Aileron moves into the airflow and creates drag. This helps to equalize the drag created by the lowered aileron on the opposite wing, and reduces adverse yaw.
BOTH REDUCE ADVERSE YAW
Elevator (General Information )
Elevator controls pitch, about the lateral axis.
Connected through mechanical linkages
How it Moves:
Tail moves UP Nose Pitches DOWN: (control yoke forward) increases the camber of the elevator and creates and upward aerodynamic force, which cause the nose to pitch down
Tail moves Down Nose Pitches UP: (control yoke back) decreases the camber of the elevator and creates a downward aerodynamic force, which causes the nose to pitch up
ALL OF THIS OCCURS AROUND THE CG
Stabilator and Anti-Servo Tab (NOT CESSNA 172S)
(General Information)
Stabilator: is the one-piece horizontal stabilizer that pivots from a central hinge point. Moves opposite of the control column (Yoke).
Stabilator’s are very sensitive to control inputs and aerodynamic loads.
Anti-Servo Tabs- DECREASE SENSITIVITY, they deflect in the same direction as the stabilator, (NOT NEEDED; included with a balance weight)
Rudder (General Information)
The rudder controls movement around the vertical axis.
Controlled by the rudder pedals. The tail moves together moves with the same rudder, increases effectiveness with airspeed.
Left rudder = left pedal
Right rudder = right pedal
*THE TAIL MOVES OPPOSITE OF THE RUDDER, and Yaws the Plane to the Side of the Rudder Pedal Movement Left rudder pedal, rudder moves to the left, tail moves to right, nose yaws to left (like a boat)
Example:
Secondary Flight Controls
Wing Flaps, Leading Edge Devices, Spoilers and Trim Systems
Flaps (General Information)
Flaps: high lift devices, increases both lift and induced drag at any AOA
Increase the Lift and Allow an Aircraft to come in for Slower Approaches while still Developing Adequate Lift.
Four Types: plain, split, slotted, and Fowler
Plain Flaps (NOT CESSNA 172S)
Bottom of the Wing Drops into the AirFlow:
Plain is the simplest form of flaps, HIGH DRAG!!!! Increases the Camber and the coefficient of Lift at any AOA.
Split Flap
The split flap is deflected form the lower surface of the airfoil produces a slightly greater increase in lift than the plain flap. MORE DRAG IS PRODUCED due to TURBULENT AIR PATTERN produces BEHIND the AIRFOIL. Produce High Drag with little additional lift (Plain is the same)
