PHAK Flashcards
In regards to aircraft what is stability?
The inherent quality of an aircraft to correct for conditions that may disturb its equilibrium and to return to or continue on the original flgith path.
What is static stability?
Refers to the aircraft’s initial response when disturbed from a given pitch, yaw, or bank.
Define Positive Static Stability
Positive static stability—the initial tendency of the
aircraft to return to the original state of equilibrium
after being disturbed.
Define Static Stability
the initial tendency of
the aircraft to remain in a new condition after its
equilibrium has been disturbed.
Define Negative Static Stability
the initial tendency of the
aircraft to continue away from the original state of
equilibrium after being disturbed.
What is Dynamic Stability?
Refers to the aircraft response over time when disturbed from a given pitch, yaw, or bank.
Define Positive Dynamic Stability
over time, the motion
of the displaced object decreases in amplitude and,
because it is positive, the object displaced returns
toward the equilibrium state.
Define Neutral Dynamic Stability
once displaced, the
displaced object neither decreases nor increases in
amplitude. A worn automobile shock absorber exhibits
this tendency.
Define Negative Dynamic Stability
over time, the motion
of the displaced object increases and becomes more
divergent.
In what two major ways does stability affect an aircraft?
Maneuverability and Controllability
Maneuverability—the quality of an aircraft that
permits it to be maneuvered easily and to withstand
the stresses imposed by maneuvers. It is governed by
the aircraft’s weight, inertia, size and location of flight
controls, structural strength, and powerplant. It too is
an aircraft design characteristic.
Controllability—the capability of an aircraft to
respond to the pilot’s control, especially with regard
to flight path and attitude. It is the quality of the
aircraft’s response to the pilot’s control application
when maneuvering the aircraft, regardless of its
stability characteristics.
Where is the Center of Lift (CL) in relation to the Center of Gravity (CG) on a plane?
Most aircraft are designed so that the wing’s CL is to the rear of the CG.
This makes the aircraft nose heavy and requires that there be a slight downward force on the horizontal stabilizer in order to balance the aircraft and keep the nose from continually pitching downward.
