Control Flashcards
In relation to controllability, control surfaces act as…
Destabilisers
Combining the tailplane and elevator forms what aircraft part?
Stabilator
Combining the rudder and elevator forms what aircraft part?
Ruddervator
The downgoing aileron is on the…
Upgoing wing
The upgoing wing has what aileron?
Downgoing aileron
The upgoing aileron is on the…
Downgoing wing
The downgoing wing has what aileron?
Upgoing aileron
How is camber affected in a wing whose aileron is downgoing?
Camber increases
Increasing camber of a wing does what to its AoA?
AoA increases (and so does the lift and drag)
Adverse yaw is yaw in what direction?
Away from the direction of roll
Why does adverse yaw occur?
Upgoing wing has greater drag (from greater lift) so pulls aircraft in its direction, away from direction of roll
What control surface design can overcome adverse yaw?
Differential ailerons
Differential ailerons increase the drag on which aileron and wing?
Upward aileron (descending wing)
Differential aileron means the ailerons differ in what way?
The downgoing wing’s aileron deflects at a greater angle than the upgoing wing
What type of drag does a differential aileron system increase?
Parasite
What kind of aileron involves greater parasite drag by creating disruptive airflow beneath the wing?
Frise-type aileron
Frise-type aileron involves what process?
Upgoing aileron’s nose protudes beneath wing and disrupts airflow
Secondary effect of the ailerons is…
Yaw
Secondary effect or rudder is…
Roll
The maximum allowable speed for maximum control deflection is called the
Manouevring speed
Manouevring speed is known by what symbol?
VA
In-flight, what are the only variables for control effectiveness?
Airspeed and control surface deflection angle
Change in turning moment =
Change in lift x Moment arm to CG
Change in lift x Moment arm to CG =
Change in turning moment
Why does doubling airspeed quadruple thee effect of the control surface deflection?
Aerodynamic forces vary with dynamic pressure so that doubling V will mean the lift coefficient is V-squared
Why does slipstream not affect aileron effectiveness?
Ailerons sit outside the slipstream
Slipstream affects what control effectiveness?
Rudder and elevator effectiveness
What is stick-force?
Moment acting on control surrface trying to return the surface to its original position
When deflected, a control surface encounters an opposing aerodynamic force that causes a moment to try and return the surface on its hinge line to its original position. What is thiss called?
Stick-force
Stick loads are greatest when…
The hinge line is at the leading edge of the control surface
Stick loads increase how?
The further forward the hinge line is on a control surface
When reducing stick-load, what aerodynamic process is targeted for reduction?
Hinge moment
How is the hinge moment reduced in inset hinges?
Distance between centre of pressure and hinge point is reduced
How does a horn balance reduce the overall hinge moment?
The horn moment opposes the hinge moment
Downside to horn balance?
Horn balance deflection will increase drag
A balance tab moves in what manner?
In opposite direction to the elevator
What name is given to a balance tab that is directly connected to the control column?
Servo tab
Control surfaces have a tendency to…at high speeds?
Flutter
What is a flutter?
Vibration resulting from changes in pressure distribution due to AoA alterations
Vibration resulting from changes in pressure distribution due to AoA alterations on a control surface is known as a?
Flutter
Mass-balancing aims to reduce/eliminate what?
Fluttering
What method is used to reduce/eliminate fluttering?
Mass-balancing
Mass-balancing involves placing a mass where?
Forward of the hinge-line
Mass-balancing forward of the hinge-line does what to the control surface’s aerodynamics?
It brings the control surface’s CG forward
Over-controlling stabilators are prevented by what aircraft part?
Anti-balance tab
An anti-balance tab differs from a balance tab how?
Anti-balance tab moves in the same direction as the control surface’s trailing edge, not the opposite
Anti-balance tabs provide what to the pilot?
Additional feel
Secondary control effect of pitch?
There isn’t one
