POF - Four Forces of Flight Flashcards
during flight, the four forces acting on the airplane are:
lift, weight, thrust, and drag
the four forces are in ___ during unaccelerated flight
equilibrium
is the upward force created by the effect of airflow as it passes over and under the wing
Lift
the airplane wing’s shape is designed to take advantage of what two principles?
Newton’s Law of Motion and Bernoulli’s principle
The reaction to downwash from the top surface of the wing and the airstream striking the wing’s lower surface causes an upward reaction in positive lift according to what law of motion?
newton’s third law of motion.
velocity increases, pressure decreases and vice versa refers to what principle
bernoulli’s principle
design factors which affect a wing’s lifting capability
planform, camber, aspect ratio, wing area
caused by the separation of airflow above the wing’s upper surface.
stall
stall always occur after the critical angle of attack regardless of:
air speed, flight attitude, or weight
total lift depends on the combined effects of
air speed and angle of attack
true or false: when speed decreases, you need to increase angle of attack to maintain the same amount of lift
true
include plain, split, slotted, and fowler
flaps
force of gravity which act vertically through the center of the airplane toward the center of the earth. opposite of lift
weight
forward acting force that opposes drag and propels the airplane
thrust
acts in opposition to the direction of the flight, opposes thrust, and limit the speed of the airplane
drag
drag caused by any aircraft surface which deflect or interfere with smooth airflow around the plane
parasite drag
true or false: if airspeed is doubled, parasite drag increases fourfold
true
drag generated by the airflow circulation around the wing as it creates lift
induced drag
phenomenon in which the earth’s surface restricts the downward deflection of the airstream from the wing, decreasing induced drag
ground effect
arrow which show the forces acting on an airplane
vectors
newtons first law
body at rest remains at rest and a body in motion remains moving at the same speed in the same direction.
newtons second law
f=ma
newtons third law
for every action there is an equal and opposite reaction
any surface which provide aerodynamic force when it interacts with a moving stream of air
airfoil
deflection of incoming airstream upward and over the wing
upwash
angle formed by the chord line of the wing and relative wind
angle of attack
downward deflection of airstream as it passes over the wing and past the trailing edge
downwash
part of the airfoil which meet meets airflow first
leading edge
portion of airfoil where airflow over the upper surface rejoins the lower surface airflow
trailing edge
characteristic curve of the airfoil’s upper and lower surfaces
camber
imaginary line drawn through the leading edge and trailing edge
chord line
airflow parallel to flight path
relative wind
airplane stalls when critical angle of attack is exceeded regardless of:
airspeed, flight attitude, weight
way to measure lift as it relates to angle of attack
coefficient of lift
stall characteristics:
mushy feeling, stall warning device identified, slight buffeting of the airplane
to recover from stall you must restore smooth airflow by
decrease angle of attack
wing design factors
wing planform, camber, aspect ratio, and total wing area
relationship between length and width of wing
aspect ratio
total surface area of the wing
wing area
refers to the shape of the wing
planform
a. shape of wing ideal for slow speeds
b. shape of wing that has a tendency to stall first at wing root
c. shape of wing combined with rectangular and tapered configurations
d. shape of wing which include delta wings
a. elliptical
b. rectangular
c. tapered
d. sweptback
angle between chord line and longitudinal axis of plane
angle of incidence
consists of two metal strips attached to the leading edge of each wing near the fuselage to ensure positive control during a stall
stall strips
true or false: drag is always a bi-product of lift
true
pilot controls of lift
changing airspeed, changing angle of attack, usage of high-lift devices
allows to steepen the angle of descent on an approach without increasing airspeed
flaps
refers to the position of landing gear and flaps
configuration
a. flap attached to the wing by a hinge.
b. flap hinged only to the lower portion of the wing.
c. flap that allows a portion of higher air pressure travel through a slot
d. flap attached to the wing by a track and roller system
a. plain flap
b. split flap
c. slotted flap
d. fowler flap
a. drag related to the structure of the plane
b. drag when currents of air over an airplane meet and interact
c. drag caused by roughness of the airplane’s surface
a. form drag
b. interference drag
c. skin friction drag
sum of parasite and induced drag
total drag
true or false: ground effect is noticeable when height is approximately equal to the wingspan of the aircraft
true
true or false: during unaccelerated flight, the four forces of flight are in equilibrium
true
true or false: as airspeed increases, angle of attack at which airfoil stalls increases
false
what is the aspect ratio of the wing below:
ws = 35ft ac = 5ft
ar = ws/ac ar = 35ft/5ft ar = 7ft
pilot methods to control lift
change air speed, change angle of attack, use high lift devices
