AVN 2100 Stability Flashcards
An airplane ____ about the longitudinal axis.
Rolls
An airplane ______ about the lateral axis.
Pitches
An airplane _____ about the vertical axis
Yaws
Trim and flaps are _______ control surfaces
Secondary
The purpose of a trim device is to:
Minimize the effort of the pilot when moving a control surface or maintaining that surface in a desired position.
Trim lessons the _____ felt by the pilot on the associated flight controls
Aerodynamic resistance
The three axes of motion intersect at the ______
Center of gravity
The center of gravity is the theoretical point where _______
The entire weight of the plane is concetrated
The center of pressure is the ______
Point along the chord line of an airfoil where life is concentrated.
The center of pressue is also known as the _______
Center of lift
Stability is the ______
Tendency of the aircraft to return to its original condition after being dispaced
A stable aircraft will ______ return to its original position
Return
An unstable aircraft will ______ from its original position
Move farther away
A neutral aircraft will ______ in its displaced position
Remain
The two types of stability are :
Static and dynamic
Positive Static stability is:
The initial tendency to return to original position
Positive Dynamic stability is:
The tendency of the aircraft to return to its original position over a period of time
With negative static stability, an aircraft tends to:
Initially displace farther from its original position
Oscillations _____ in a displaced aircraft with ________
Negative dynamic stability
Oscillations will remain the same in a displaced aircraft with ________
Neutral dynamic stability
If an aircraft returns to its original position thorugh a series of successively smaller oscillations, it has _______
Positive dynamic stability
Longitudinal stability involves _____ motion about the ______ axis
Pitching, lateral
If an aircraft naturally returns to its original attitude it is
Longitudinally stable
The center of pressure changes with the _____
Angle of attack
The center of gravity is located _____ of the center of pressure
Fore or aft
As the angle of attack increases, the center of pressure _______
Increases
As the center of pressure moves further aft of the CG, the aircraft becomes _____ longitudinally stable
Less
The horizontal stabilizer is mounted with a ______ angle of incidence to provide _______
Negative, tail down force
When the wings angle of attack is increased, the horizontal stabilizer’s angle of attack _____, thus _______ the tail down force
Increases, decreases, decreasing
Decreasing the tail down force produces a _______
Nose down moment
For positive longitudinal stability, when the nose goes up, tail down force should _____
Go down
Longitudinal stability deponds on the _____ and its ______ from the _______
Size, distance, center of gravity
The larger the ______, the _______ the longitudinal stability
Horizontal stabilizer, greater
The greater the distance of the tail from the ______, the _______ the longitudinal stability
Center of gravity, greater
4 characteristics of CG too far forward:
Higher stalling speed, more stable, slower cruise speed, not enough elevator authority
4 characteristics of CG too for aft:
Lower stall speed, faster cruise speed, less stable (easier to stall and spin and harder to recover)
Because of the effects of the propeller slipstream, reduced thrust will reduce the _____ , meaning that the nose will _____
Taildown force, drop
Directional stability is stability about the _____ axis
Vertical
When an aircraft yaws, the vertical stabilizer has an _____ with respect to the relative wind
Angle of attack
When yawing, the induced angle of attack of the ______ produces a restorative ______
Fin, moment
The farther from the ______ that the vertical stabilizer is, the greater the _______
Center of gravity, directional stability
The larger the ______, the greater the ______ stability about the vertical axis
Vertical stabilizer, directional
“Keel Surfaces” refer to _______
Side surfaces of the aircraft
When an airplace is _____, keel surfaces are exposed to the relative wind.
Yawed
The greater the area of the keel surface, the ____ it contribution to ________
Greater, directional stability
Lateral stability is built into an aircraft with four things:
Dihedral, swept wings, high keel surfaces, low CG
What is dihedral?
The angle that the wings are inclined upward from the fuselage towards the wingtips
Dihedral increases ______ stability because the increased ______ of the low wing increases its ________
Lateral, angle of attack, lift
Why do swept back wings contribute to lateral stability?
The lower wing exposes more of its span to the airflow when rolled
Uneven fuel burning may result in _______
Lateral instability
What is dutch roll?
A lateral motion that is a combination of rolling/yawing, side to side oscillations
A series of uncoordinated turns alternately in opposite directions is:
Dutch roll
The differential lift created between the two wings when turning creates a _____ differential, leading to ______
Drag, adverse aileron yaw
Increased dihedral increases the tendency to ______
Dutch roll
Does dutch roll resolve itself on most aircraft?
Yes
Typically, dutch roll is the result of two things:
- A sharp wind gust against one wing 2. A very large control input that is suddenly released
Inputing a very large control movement and then suddenly releasing it may induce ______
Dutch Roll
