Controls Flashcards
Elevator pitches around the
Lateral axis
Rudder yaws around
Normal axis
Ailerons roll around
The longitudinal axis
Problems with controls at high speeds
Large control surfaces produces high control forces
How speed effects controls
Larger control movements at high speed are physically hard for the pilot than at slow speed
7 Types of aerodynamic balances
Modify forces on the control surface Inset hinge Horn balance Internal balance Balance tab Anti balance tab Servo tab Spring tab
Inset hinge
Hinge moment distance is reduced
Reduced feel
Reduced work on the control column
Max distance from the fwd hinge is 25%
Horn balance
Reduces the amount of force on the surface
Make the controls lighter and more effective
Forces hold the control in place
Internal balance
Sealed internal gap
Pressure differential causes an assist with the hinge moment
Reduces control column forces
Balance tab
Manual balance
Deflects in the opposite direction
Not very efficient due to going in the opposite direction
Make control surfaces lighter
Reduces the load felt at the control column
Reduces control effectiveness
Anti balance tab
Makes control surfaces heavier
The tab moves with the control surface
Improves efficiency
Less possibility of over stressing at higher speeds
Servo tab
Pilot is connected to the tab itself
Move and it creates an aerodynamic force which moves the tab in the opposite direction
Control authority decreases at slow speeds
Very effective at high speeds
Not very effective at slow speeds with small aerodynamic forces being produced
Spring tab
Acts like a servo tab at high speed
Acts like a balance tab at slow speeds
Mass balancing
Adding masses ahead of the hinge line to reduce flutter
Power assisted controls
Still some natural feel but mostly powered
Fully powered controls and how to avoid the risks
No feedback
Artificial feel is required
Provide all the power to move control surfaces
Q feel system generates artificial forces in proportion to dynamic pressure
AoA in a roll
Downgoing is greater
Up going is reduced
Aerodynamic damping in the roll
The up going wing is producing more CL which is creating more Di which is forcing the a/c to yaw in the opposite direction
Longer wings increase this
Variable incidence tailplane
Whole a/c tailplane moves Common on jet a/c Creates a large pitching moment Greater aileron authority Leading edge down, pitch up Leading edge up, pitch down
High T tail
Improves L/D ratio Stays out of downwash Ground effect reduces Heavier structural requirements on the tail Could go into the deep stall
Rate controls
Ailerons
Displacement controls
Rudder
Elevator
Frise ailerons
Reduces adverse aileron yaw
Increases parasite drag on the downgoing wing to counteract the induced drag on upgoing
Differential ailerons
Upgoing aileron deflects less than the downgoing and produces more drag to counteract the adverse aileron yaw
Secondary effects of the rudder, aileron and elevator
Rudder - roll
Aileron - sideslip the yaw
Elevator - none
Using a servo tab and during the flight the elevator jams, what happens the pitch control
Pitch control sense is reversed due to the controls being attached to the tab
When trimmed fo 0 stick force, what causes less drag
Horizontal trimmable stabiliser than a trim tab
On a trim tab runway what causes less control difficulty
Trim tab runway compared to a horizontal trimmable
Stabiliser trim and flutter
Less sensitive to it
Flutter is also dependant upon IAS
Difference between trim tab and servo tab
Trim tab reduces stick force to 0
Servo tab reduces stick force
