POF - Stability Flashcards
true or false: airplane that is inherently stable will require less effort to control
true
characteristic of an airplane in flight that causes to return to a condition of equilibrium or steady flight after it is disturbed
stability
initial stability tendency to return to the position from which it was displaced is termed
positive static stability
stability tendency made through a series of small oscillations
positive dynamic stability
characteristic of an airplane that permits to maneuver easily and withstand the stress resulting from it
maneuverability
capability of an airplane to respond to control inputs especially on attitude and flight path.
controlability
three axes of flight and movement
longitudinal - roll
lateral - pitch
vertical - yaw
common reference point of the three axes and the theoretical point where the entire weight of the airplane is concentrated
center of gravity
a. controls the roll movement
b. controls the pitch movement
c. controls the yaw movement
a. aileron
b. elevator
c. rudder
longitudinal stability involves which motion or axis
pitching motion or lateral axis
point along the wing chord line where lift is concentrated (center of lift)
center of pressure
true or false: to achieve longitudinal stability, most planes are designed slightly nose heavy
true
when the CG is within the approved range, the airplane is:
controllable and its longitudinal stability is satisfactory
true or false: if CG is too far forward, elevator effectiveness will be insufficient to lift the nose,
true
true or false: if CG is too far aft, elevator shall not be effective and may be difficulty to recover from a stall or spin.
true
true or false: always follow the POH loading recommendation or guidelines.
downward force used to counteract nose-down tendencies due to CG
tail-down force (horizontal stabilizer)
true or false: downwash from the propeller and wings passing over the horizontal stabilizer influence longitudinal stability
true
results to a nose down pitching tendency due to the reduction of downwash from the wings and the propeller which reduce elevator effectiveness.
reduction of power
will decrease downwash on the horizontal stabilizer from the wings and propeller slipstream which causes the nose to pitch down
power reduction
determined where propeller is mounted and the general direction which thrust act
thrust line
lateral stability involves which motion or axis
rolling or longitudinal axis
design features that influence lateral stability:
weight distribution, dihedral, sweepback, and keel effect.
true or false: you have no control of design features for lateral stability but you can control the distribution of weight to improve it.
true
most common design for lateral stability. refers to the upward angle of the airplane’s wings with respect to the horizontal.
dihedral
involves lateral stability in which wings are angled backward from the wing root to the wing tips.
sweepback
steadying influence exerted by the side area of the fuselage and the vertical stabilizer
keel effect
directional stability involves which motion or axis
yaw or vertical axis
interaction of lateral and directional stability in which a combination of rolling and yawing oscillations caused by either your control input or by wind gusts.
dutch roll
interaction of lateral and directional stability which is associated with airplanes that have strong directional stability in comparison with lateral stability
spiral in instability
true or false: if air speed is low, the required angle of attack to maintain lift may exceed which may cause a stall
true
type of stall with low power conditions
power-off stall
type of stall with high power condition
power-on stall
type of stall which involves higher than the normal speed
accelerated stall
type of stall when the pilot tries to compensate for overshooting a runway during a turn from base to final while on landing approach
crossed-control stall
signs of stall
mushy feeling in flight control, less control effectiveness, stall warning
steps how to recover from a stall
decrease angle of attack, increase power via throttle, adjust power as required upon recovery
aggravated stall which results in the airplane descending in a helical or corkscrew path
spin
to enter a spin, an airplane must first be ___
stalled
true or false: although both wings are stalled, one wing is stalled more than the other
true
type of spin where roll and yaw are in the same direction
erect spin
type of spin where roll and yaw are in opposite direction
inverted spin
type of spin which involves only the yaw
yaw
spin recover (PARE)
power - idle
aileron - neutral
rudder - opposite direction of spin
elevator forward
first stage of spin from the time the plane stalls and rotation starts
incipient spin
second stage of spin which is after the incipient spin where the actual spin occurs
fully developed spin
third stage of the spin where anti spin procedures have been executed
recovery
most aircrafts are designed to display both___ and ___ stability
positive static and positive dynamic stability
common point of longitudinal, lateral, and vertical axis
center of gravity
longitudinal stability is associated with the relationship of
center of pressure and center of gravity, power change, and the design of the horizontal stabilizer
lateral stability involves what factors
wing dihedral, sweepback, keel effect, and weight distribution
Directional stability or stability of the vertical axis is maintained by
vertical tail
most likely to occur on aircraft with weak directional stability and strong lateral stability
dutch roll
a spin will not develop until both wings are __
stalled
in relation to center of gravity, which direction would the center of pressure normally move as angle of attack is increased on a cambered wing
forward
what factors affect longitudinal stability of an airplane at high power settings and low air speed
On many training aircraft, an increase in thrust increases the pitching moment and nose heaviness due to the placement of the thrustline of the aircraft. This helps counteract the longitudinally destabilizing
effect of increased downwash that results from an increase in power and extension of high lift devices.
why are high wing aircrafts normally designed with less dihedral than low wing aircraft
Upwash passing around the fuselage just ahead of the wing tends to roll a high wing aircraft toward the upright position, contributing to lateral stability. In a low wing airplane, the downwash around the fuselage tends to be laterally destabilizing since it tends to increase the roll. The amount of dihedral is adjusted to compensate for the effects of fuselage upwash and downwash resulting in a greater requirement for dihedral in a low wing airplane than in a high wing configuration.
Does propwash result from high power setting increase or decrease the contribution of wing dihedral to the lateral stability of an airplane
decrease
true or false: when landing in gusty winds, airspeed should be increased above normal to help guard against a stall
true
