Basic Theory Flashcards
Scalar
quantity that represents only magnitude
Vector
quantity that represents magnitude and direction
Displacement (s)
distance and direction of a body’s movement
Velocity (V)
speed and direction of a bod’s motion, the rate of change of position
Speed
scalar equal to the magnitude of the velocity vector
Acceleration (a)
rate and direction of a body’s change of velocity
Force (F)
push or pull exerted on a body
Mass (m)
quantity of molecular material that comprises an object
Volume (v)
amount of space occupied by an object
Density (ρ)
mass per unit volume
ρ = mass/volume
Weight (W)
force with which a mass is attracted toward the center of the earth by gravity
Force (F)
mass times acceleration
F= m (x) a
Moment (M)
created when a force is applied at some distance from an axis or fulcrum, tends to produce rotation about that point. A vector quantity equal to Force time distance from the point of rotation that is perpendicular to the force.
Work (W)
scalar quantity
W= F (x) s
Power (P)
rate of doing work or work done per unit of time
P = W/t
Energy
scalar measure of a body’s capacity to do work
TE= PE + KE
Potential Energy
ability of a body to do work because of its position or state of being. Function of mass (m), gravity (g), and height (h).
PE= weight (x) height = mgh
Kinetic energy
ability of a body to do work b/c of its motion. Funcition of mass (m) and velocity (V).
KE = 1/2mV ²
Work
changes position to give potential energy or motion to give kinetic energy
Newton’s First Law
Law of Equilibrium
“Body at rest tends to remain at rest and a body in motion tends to remain in motion in a straight line at a constant velocity unless acted upon by some unbalance force
Equilibrium
absence of acceleration, either linear or angular
Equilibrium flight
exists when the sum of all forces and the sum of all moments around the center of gravity are equal to zero. thrust, drag, lift and weight cancel each other out
Trimmed flight
exists when the sum of all moments around the center of gravity is equal to zero. Sum of forces may not be equal to zero. DOES NOT NEED TO BE IN STRAIGHT AND LEVEL FLIGHT
Newton’s Second Law of Motion
Law of Acceleration
“An unbalanced force (F) acting on a body produces an acceleration (a) in the direction of the force that is directly proportional to the mass (m) of the body”
a=F/m a= (Vout (-) Vin)/time
Newton’s Third Law of Motion
Law of Interaction
“For every action, there is an equal and opposite reaction; the forces of two bodies on each other are always equal and are directed in opposite directions
Static pressure (Ps)
the pressure that particles of air exert on adjacent bodies
Air density (ρ)
total mass of air particles per unit of volume. Decreases with an increase in altitude
Temperature (T)
measure of the average random kinetic energy of air particles
Average lapse rate
Linear temperature decrease for each 1000 ft increase in altitude. 2°C (3.57°F) per 1000 ft up to 36,000 ft
Humidity
amount of water vapor in the air
as humidity inc, air density dec
Viscosity (µ)
measure of the air’s resistance to flow and shearing
inc as temp inc
Local speed of sound
rate at which sound waves travel thru a particular air mass
dependent only on the temperature of the air
Standard atmosphere
set of reference conditions giving representative values of air properties as a function of altitude
General Gas Law
set the relationship b/w pressure (P), density (ρ), and temperature (T)
P=ρRT
Altitude
defined as the geometric height above agiven plane of reference
True altitude
actual height above sea level
Pressure altitude (PA)
height above the standard datum plane (22.92 in. Hg)
Density altitude (DA)
altitude in the standard atmosphere where the air density is equal to local air density. Found by correcting pressure altitude for temp and humidity.
Predictor of aircraft performance.
Steady airflow
Exists if at every point in the airflow static pressure, density, temp and velocity remain constant over time. Particles do not cross streamlines.
Streamtube
collection of many adjacent streamlines
Continuity Equation (ṁ)
Amount of mass passing any point in the streamtube
ṁ= ρAV
Continuity Equation
ρ1A1V1 = ρ2A2V2 A1V1= A2V2
Static pressure (ps)
the pressure particles of air exert on adjacent bodies
Dynamic pressure (q)
measure of impact pressure of a large group of air molecules moving together
q= (1/2)ρV ²
Total pressure (H)
sum of static and dynamic pressure
inc in static results in dec in dynamic, and vice versa
H = ps + (1/2)ρV ²
Bernoulli’s equation
H= ps + q
Airspeed Measurement equation
q= H (-) Ps
pitot static system
consists of pitot tube that senses total pressure (H), static port that senses static pressure (Ps) and differential pressure gauge
pitot tubes used for…
measuring total pressure
static port measures…
static pressure
Indicated airspeed (IAS)
actual instrument indication of dynamic pressure the airplane is exposed to
Instrument error
caused by indicator errors and errors due to the pysical location of the static port
Calibrated airspeed (CAS)
indicated airspeed corrected for instrument error
compressibility error
caused by ram effect of air in pitot tube resulting in higher than normal airspeed indications
Equivalent airspeed (EAS)
true airspeed at sea level on a standard day that produces the same dynamic pressure as the actual flight condition
Pitot tubes
used to measure total pressure
Static port
measures static pressure
Indicated airspeed (IAS)
actual instrument indication of the dynamic pressure the plane is exposed to during flight
instrument error
caused by the indicator errors and errors due to the physical location of the static port on the aircraft
True airspeed
actual velocity at which an airplane moves through an air mass
Ground speed
airplane’s actual speed over the ground
GS= TAS (-) HEADWIND
GS= TAS (+) TAILWIND
aircraft
any device used or intended to be used for flight in the air
airplane
mechanically driven fixed-wing aircraft, heavier than air, which is supported by the dynamic reaction of the air against its wings
fuselage
basic structure of the airplane to which all other components are attached
truss
consists of metal/wooden frame over which a light skin is stretched. truss supports entire load
full monocoque
skin shell that supports entire load
semi-monocoque
modified monocoque with skin, frame members, and stringers that share the load
wing
airfoil attached to the fuselage designed to produce lift
ailerons
attached to wing to control roll
empennage
assembly of stabilizing and control surfaces on the tail of an airplane
greatest stabilizing force
elevators
attached to horizontal stabilizer to control pitch
landing gear
permits ground taxi operation and absorbs shock encountered during takeoff and landing
engine
provides thrust necessary for powered flight
mean camber line (MCL)
line halfway b/w upper and lower surface of an airfoil
chord line
infinite line that passes thru leading and trailing edges of an airfoil
root chord (cr)
chord at the wing centerline
tip chord (ct)
chord at wing tip
average chord (c)
avg of every chord from wing root to wingtip
camber
ma distance b/w mean camber line and chord line
measured perpendicular to chord line
Aerodynamic center
point along chord line around which all changes in the aerodynamic force take place
Wingspan (b)
length of wing measured wingtip to wingtip
Wing area (S)
apparent surface area of a wing from wingtip to wingtip
S=bc (wing area= wingspan x avg. chord
Taper
reduction in chord of an airfoil from root to tip
sweep angle
angle b/w lateral axis and line drawn 25% aft of leading edge
Aspect ratio (AR)
ratio of wingspan to avg chord
AR= b/c
Wing loading (WL)
ratio of plane’s weight to surface area of wings
WL=W/S
Angle of incidence
angle b/w plane’s longitudinal axis and chord line of wing
Dihedral angle
angle b/w spanwise inclination of wing and lateral axis (upward slope of wing when viewed from front)
Anhedral angle
negative diheral angle
Pitch attitude
angle b/w plane’s longitudinal axis and the horizon
flight path
path of plane described by center of gravity as it moves thru an airmass
Relative wind
airflow the plane experiences as it moves thru the air
angle of attack (AOA)
angle b/w relative wind and chord line of airfoil
Spanwise flow
airflow that travels along span of wing, parallel to leading edge
produces no lift
Chordwise flow
air flowing at right angle to leading edge of airfoil
only airflow that produces lift
