Exam 1 Flashcards
The atmoshphere is made of _% Nitrogen, _% oxygen, and _% other.
78, 21, 1
The higher the temperature, the ____ the molecules are moving
faster
affects the density of the air because when air is heated it expands
Temperature
Air is ____ _____ when it is hot. Air is ______ when it is cold
less dense, denser
affects the density of the air because water vapor is less dense than air
Humidity
Air is ____ dense when there is high humidity
less
Air is ______ when there is low humidity
denser
affects the density of the air because there are fewer air molecules the further up you go
Altitude
Air is _____ dense on hot, humid days, and at high altitude
least
air is _____ dense on cool, dry days, near sea level.
most
____ and ___ fall at a constant rate.
air temperature and pressure
four forces on an airplane
lift, drag, thrust, weight
CG
center of gravity
what is weight
weight is a force caused by the gravitational attraction of the earth
what is lift
lift is a mechanical force generated by a solid object moving through a fluid
Newton’s 3rd lay applies
for every action there is an equal and opposite reaction
what is drag
drag is a mechanical force generated by a solid object moving through a fluid
what is thrust
thrust is a mechanical force generated by the engines to move the aircraft through the air
aerodynamics
the study of air in motion
a branch of fluid mechanics that deals with the motion of air and other gaseous fluids
airfoil
a structure with curved surfaces that results in lift being formed
air flows ___ over the top of the wing
faster
The Bernoulli Effect accounts for approximately ___% of the lift of the wing
90
Newton’s 3rd lay of motion accounts for ___% of the lift.
10
bigger difference in pressure means…
more lift that is created
a moving stream of fluid in contact with a curved surface will tend to follow the curvature of the surface rather than continue traveling in a straight line
coanda effect
How can we increase the camber shape of an airflow
by increasing the angle that the wing meets the air
the more cambered the airflow
the greater the lift
Center of pressure
a mathematical point, reflecting the lowest air pressure on the top of the wing, on the greatest pressure differential between the top and the bottom of the wing
airfoil
anything used to create a useful reaction from the air (lift) (thrust)
leading edge
the front part of the airfoil
trailing edge
the rear fo the airfoil
chord line
a line that extends from the leading edge directly to the trailing edge
camber
refers to the curvature of the wing, or the curvature of the air over, or under, the wing
span
the lengthwise of the wing
chord
he width of the wing
aspect ratio
span/chord
dihedral angle
angle of wing from plane to wingtip- purpose is stability
angle of attack
angle of wing to the oncoming air
angle of incidence
angle of elevators to oncoming wind
mean camber line
refers to an imaginary line, created mathematically, when you subtract the distance from the chord line to the lower camber from the distance from the chord line to the upper camber
mean aerodynamic chord
the distance between the leading and trailing edge of the wing, measured parallel to the normal airflow over the wing
LIFT=
Cl 1/2 V^2 Sp
what does each part of the lift equation stand for
L=Cl (1/2) V^2 Sp
Cl= AOA to graph
V= velocity of the air in feet per second
S= surface area of the wing in square feet
P= reek letter RHO= density of the air in slugs/ft^3
parasite drag
the drag produced by air flowing over surfaces not involved in producing lift
induced drag
the part of the drag of an airfoil caused by the lift, that is, the change in the direction of the airflow
profile drag
parasite drag of the airfoil
what are the 3 types of parasite drag
pressure drag
skin friction drag
interference drag
the drag resulting from air impining upon something
pressure drag
the drag resulting from the friction of the air sliding across a surface or the adhesion of the air trying to stick to a surface of a wing or aircraft
skin friction drag
the drag resulting from the turbulence where surfaces meet at 90 degree angles or less
Interference drag
pressure drag solution
make frontal area smaller and add boat tail
skin friction drag solution
make wing or aircraft shorter, make the surface smoother
interference drag solution
add fillets and fairings to cover gaps and eliminate acute angles
what is a result of induced drag
wing vortex
wingtip vortex
high pressure air from below the wing trying to reach the low pressure air above the wing
a combination of the effects of the wake tip vortices and tilted lift vector result in induced ___
drag
things that make induced drag worse
a high AOA
flying at a high altitude
flying slow
flying with a heavy aircraft
wing design
induced drag solutions
high aspect ratio wings
rounded wing design
winglets
when does a stall occur
when the angle of attack exceeds the value at which the maximum lift is created
it can happen at any speed
what is the drag calculation
Drag= Cd 1/2 V^2 Sp
what does each part of the drag equation stand for
D= Cd 1/2 V^2 Sp
Cd= compute AOA with the graph
V= velocity of the air in feet per second
S= surface are of the wing in square feet
P = density of the air in slugs/ft^3
solution will be in LBS
PP1
what is the drag on the wing of an aircraft if
the aircraft speed is 180mph
the aircraft is flying at 3000 feet
the wing surface area is 200 square feet
the aircraft is flying at an AOA of 12 degrees
1061.61
PP2
Cd=0,02
altitude=28000ft
p=0.000957
speed= 202mph = 296.26734 feet/second
wing area 590 square feet
495.60
PP3
Cd=0.06
altitude- 15000 ft=p=0.001496
speed=240 knots= 405.0744 feet/second
wing area 135 square feet
994.14
PP4
Cd=0.13
altitude=8000ft=p=0.001869
speed =150 knots=253.1715 feet/second
wing area 100 square feet
778.67
what is ground effect
when an aircraft flies less than one-half its wingspan above the ground the air is forced down and deflected which effectively increases the AOA without increasing drag
what it boundary layer
the airflow next to the airfoil
what does a turbulent boundary layer do
ncrease drag
what do wing fences do
prevent entire wing from stalling at once
obstruct span wise airflow
what do vortex generators do
they pull high energy air down to the surface preventing airflow separation (stall)
what is planform
shape of the wing as viewed from above
is there a best wing shape for flight
no
what is aspect ratio
span/width
greater aspect ratio means
less induced drag
Rectangular wing stall characteristics and price
roots stall first
gives advance stall warning
cheap and easy to produce and repair
moderate taper wing stall characteristics and aerodynamic contributions
whole wing tends to stall at once (many planes have change in camber to counteract)
more lift
less drag
less weight
High taper wing aerodynamic charactersticks and stall
much more lift
much less drag and weight
tends to stall from wingtips first
pointed wing tip stall characteristics
stalls from wing tip first
sweptback wing pros
efficient at high speeds
delays shock waves- can fly closer to speed of sound
sweptback wing cons
can get dutch roll
need a yaw dampener to prevent dutch roll
stall from wingtips first
unfavorable at slow speeds
elliptical wing stall and earodynamic characteristics
little warning of stall
entire wing will stall at the same time
most efficient subsonic wing
much less induced drag
fuselage
the body of an aircraft
empanage
the whole tail assembly
nacelle
powerplant - engine and mounting location
wings
provides the majority of the lift an airplane requires for flight
landing gear
struts- absorb th eimpact of the landing
formers
placed in a fuselage to give the fuselage skin its shape and rigidity
stringers
metal or wood braces placed between wing ribs, or bulkheads in fuselage, to give stiffening strength to the wing skin or structure
longeron
a principle fore and aft structural framing member of a fuselage that typically crosses several points
bulkeads
a vertical wall within the fuselage
firewall
a special bulkhead that goes between the engine and the fuselage or wing
starboard
right side
port
left side
forward
the front of the aircraft
aft
the back of the aircraft
fuselage stations
nose to tail
datum
where all measurements start
is wherever the manufacturer decides it is
wing station
distance in inches from ceterline of the fuselage to the wing tips
waterline stations
verticle distance in inches from centerline fo the fuselage
distances up are positive
distances down are negative
vertical fin
vertical surface sticking up above the fuselage at the tail
vertical stabilizer
vertical surface sticking up above the fuselage at the tail
dorsal fin
extension of the verticle stabilizer running forward from the vertical stabilizer
ventral fin
vertical stabilizer on the bottom of the aircraft
lift struts
transmit lift loads from the wings to the fuselage
wign ribs
the chordwise structural member in a wing that gives the wing its shape
wing spar
a structural beam that transmits lift and load and loading loads to and from the fuselage
main landing gear
the wheels that suppost most of the weight of the aircraft
auxiliary landing gear
stabilize the aircraft and support less weight
control surface
a movable airfoil, or any surface used to control the aircraft in flight
primary flight controls
elevator, rudder, ailerons
secondary flight controls
modify the effects of the primary flight controls or air flows
aileron
roll
longitudinal rotation about the longitudinal axis
lateral stability
elevator
pitch
rotation about the lateral axis
longitudinal stability
rudder
yaw
rotation about the vertical axis
directional stability
adverse yaw
the aircraft may roll one way but directionally turn the opposite
the adverse yaw is due to an imbalance of drag at the wing tips between he left and right wing
how to fix adverse yaw
we make the parasite drag on the one side great enough to offset the induced drag on the other side
we raise the up aileron more so it catches more air than the down aileron. This is called differential ailerons
hat makes flight controls perform better
distance from CG
amount fo deflection
size of control surface
velocity of the air over the surface
slats
high lift device typically found on jets
like flaps but on leading edge
assist in changing camber/ curvature of the wing
trim tabs
econdary flight controls, which modify the position of the primary flight controls
used to get flight control settings just right
flight spoilers
kill lift and create more drage
ground spoilers
to maximize wheel brake efficiency
speed brakes
speed brakes are used to create drag to slow the airplane
what is the standard day
59 F, sea level, 0 humidity
what happens if the four forces of flight are all equal
velocity and altitude are constant
what is newtons 1st law
the four forces
what is Bernoulli’s principle
As velocity increases, pressure decreases. Pressure
on top of the wing lower than beneath the wing. Pressure
differential between the top and bottom = lift.
why were early wing designs ditched
Flat lower surface is not optimal aerodynamically. We started to
make more streamlined, more lift/less drag, and smoother wings
Transonic airfoils and their unique design, why?
Circular arc supersonic airfoil (flying saucer)
➔ Double wedge supersonic airfoil (diamond shaped)
➔ They reduce air velocity over upper surface and delays the drag
that occurs near the speed of sound
boundary layer- laminar
near leading edge, air is still smooth
boundary layer- transition
air beginning to become turbulent but not building up
in height yet
boundary layer- turbulent
at end of wing, air is taller in height and not flowing
smoothly
what are longer antennas used for
radio comms and nav
what are shorter antennas used for
high frequency data
slipping turn
means uncoordinated turn- not enough rudder or even
opposite rudder
skidding turn
means too much rudder in direction of turn
