Stability Flashcards
What is a stable aircraft?
Ability to return to a flight condition after a disturbing force has been removed without pilot input.
Static stability
Aircraft’s immediate response
Dynamic stability
Aircrafts long term response
Statically stable meaning
Body returns to equilibrium immediately.
Static neutral stability meaning
Body will take up a new equilibrium position
Statically unstable
Body diverges from its equilibrium position
Active stability meaning
Achieved by automatic operation of flight controls
Passive stability meaning
Interaction between airflow and aircraft
Longitudinal stability- movement?
Pitch
Lateral stability- movement?
Roll
Directional stability- movement?
Yaw
Device for passive lateral stability?
Dihedral angled wings
Difference between short term pitch oscillations and phugoids?
STPOs last around 1 second and don’t change altitude. Phugoids last around 30 seconds and changes altitude.
What does a flap type control surface do?
Changes camber of that part of aerofoil
What is lift force affected by?
Density of air, velocity of airflow, size and shape of control surface, angle of deflection
What is the cause of aileron yaw?
Down aileron increases the drag, the up aileron has a smaller increase.
What is a frise aileron
Hinged on upper surface, nose of flap pushed into opposite direction a little bit
What is a Differential aileron
Aileron moves up more than down.
How do we reduce stick loading
Aerodynamic balance
What are the devices used in trimming?
Fixed trim tabs, variable trim tabs or variable incidence tailplanes
What is flutter
Rapid undamped oscillations of a control surface
How do we overcome flutter?
Mass balancing. Adding weight forward of the hinge line to bring CofG forward.
Uses of Spoilers
Lift dump, role control, speed breaks
