Shared Flashcard Set

Details

Aerodynamics I
Definitions/Questions for Aero Chapt 1-6
161
Other
Professional
03/07/2009

Additional Other Flashcards

 


 

Cards

Term
Scalar
Definition
A quantity that represents only magnitude, e.g., time, temperature, or volume.
Term
Vector
Definition
A quantity that represents magnitude AND direction. Commonly used to represent displacement, velocity, acceleration or force.
Term
Displacement
Definition
the distance and direction of a body's movement.
Term
Velocity
Definition
The speed and direction of a body's motion, the rate of change of position.
Term
Speed
Definition
A scalar equal to the magnitude of the velocity vector.
Term
Acceleration
Definition
The rate and direction of a body's change of velocity. (gravity = 32.174 ft/s^2)
Term
Mass
Definition
The quantity of molecular material that comprises an object.
Term
Volume
Definition
The amount of space occupied by an object.
Term
Density
Definition
Mass per unit volume. D = m/v
Term
Weight
Definition
The force with which a mass is attracted toward the center of the earth by gravity.
Term
How to add vectors
Definition
Place head of first vecotr to tail of second, draw third vector from tail of first to head of second.
Term
Force
Definition
Mass times acceleration. F = ma
Term
Moment
Definition
Created when a force is applied at some distance from an axis or fulcrum and tends to produce rotation about that point. M = F x d
Term
Work
Definition
When a force acts on a body and moves it. it is a scalar. W = F * s
Term
Power
Definition
The rate of doing work or work done per unit of time. P = W/t
Term
Energy
Definition
A scalar measure of a body's capacity to do work. TE = PE + KE
Term
Potential Energy
Definition
The avility of a body to do work because of its position or state of being. PE = mgh
Term
Kinetic Energy
Definition
The ability of a body to do work because of its motion. KE = 1/2 mV^2
Term
Newton's first law
Definition
A 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 velicity unless acted upon by some unbalanced force.
Term
Equilibrium
Definition
The absence of acceleration, either linear or angular.
Term
Equilibrium Flight
Definition
Exists when the sum of all forces and the sum of all moments around the center of gravity are equal to zero.
Term
Trimmed flight
Definition
Exists when the sum of all moments around the center of gravity is equal to zero.
Term
Newton's second law
Definition
F = ma
Term
Newton's third law
Definition
For every action there is an equal and opposite reaction.
Term
Static Pressure (Ps)
Definition
The pressure particles of air exert on adjacent bodies. Ambient static pressure is equal to the weight of a column of air over a given area. It decreases with an increase in altitude.
Term
Air density
Definition
The total mass of air particles per unit of volume. D = m/v. Density decreases with an increase in altitude.
Term
Temperature
Definition
A measure of the average random kinetic energy of air particles.
Term
Average lapse rate
Definition
2C/3.57 F per 1000ft until 36,000ft. From 36,000 to 66,000 ft the air remains at a constant -56.5C/-69.7F.
Term
Isothermal Layer
Definition
The area of constant temperature (36000ft - 66000ft).
Term
Humidity
Definition
the amount of water vapor in the air. As himidity increases, air density decreases.
Term
Viscosity
Definition
A measure of the air's resistance to flow and shearing. Air viscosity incerases with an increase in temperature.
Term
Local speed of sound
Definition
The rate at which sound waves travel through a particular air mass. As temperature increases, speed of sound increases.
Term
Standard atmosphere
Definition
29.92 in HG/1013.25 mb
59F/15C
3.57F/2C per 1000 ft.
.0024 slugs/ft^3 / 1.225 g/l
661.7 kts/ 340.4 m/s
Term
General Gas Law
Definition
P = (row)rt
Term
Altitude
Definition
The feometric height above a given plane of reference.
Term
True altitude
Definition
The actual height above mean sea level.
Term
Pressure altitude (PA)
Definition
The height above the standard datum plane.
Term
Density Altitude
Definition
The altitude in the standard atmosphere where the air density is equal to local air density. It is found by correcting PA for temperature and humidity deviations from the standard atmosphere.
Term
How is DA used
Definition
It is not used as a height reference. It is used as a predictor of aircraft preformance. A high DA will decrease the power produced by an engine because less oxygen is availiable for combustion and it will reduce the thrust produced by a propeller or jet engine because fewer air molecules are availiable to be accerlerated.
Term
How does a vector quantity differ from a scalar quantity?
Definition
A vector quantity expresses both magnitude and direction and a scalar expresses only magnitude.
Term
How are Force and Moment related?
Definition
A force is a push or pull exerted on a body. It tends to produce motion along a line. A moment is a tendency to produce motion about a point or axis. It is created by applying force to a lever arm to induce rotational motion about an axis.
Term
Under what conditions can both an airplane traveling at a constant speed and direction and an airplane parked on the flight line be in equilibrium?
Definition
When the sum of the forces and moments about the center of gravity equal zero.
Term
What is the difference between trimmed flight and equlibrium flight?
Definition
trimmed flight = sum of all moments equals zero. eqililibrium flight = sum of all moments AND forces equal zero.
Term
What change in atmospheric static pressure occurs with an increase in altitude?
Definition
It decreases.
Term
What change in air temperature occurs in the standard atmosphere from sea level through 66,000 ft?
Definition
Temp decreases by 2C per 1000 feet until 36,000 ft and an isothermal layer with a constant temp of -56.5C exists from 36,000 to 66,000.
Term
What change in air density occurs with an increase in humidity?
Definition
Air density decreases with increasing humidity.
Term
What change in air viscosity occurs with an increase in temperature?
Definition
Viscosity increases with an increase in temperature.
Term
What is the primary factor affecting the speed of sound in air?
Definition
Temperature.
Term
Aircraft
Definition
Any device used or intended to be used for flight in the air.
Term
Airplane
Definition
A heavier than air fixed wing aircraft that is driven by an engine driven propeller or a has turbine jet and is supported by the dynamic reaction of airflow over its wings.
Term
Fuselage
Definition
The basic structure of the airplane to which all other components are attached.
Term
Truss fuselage
Definition
metal/wooden frame over which a light skin is stretched. Very strong and easily repaired but quite heavy.
Term
Full Monocoque fuselage
Definition
Extremely light and strong because it consists of only a skin shell which is highly stressed but almost impossible to repair if damaged.
Term
Semi-monocoque fuselage
Definition
A modified version of monocoque having skin, transverse frame members, and stringers, which all share in stress loads and may be readily repaired if damaged. (T-34C)
Term
The Wing
Definition
An airfoil attached to the fuselage and is designed to produce lift.
Term
Flaps/slots
Definition
High lift devices attached to the wing to increase lift at low airspeeds.
Term
The Empennage
Definition
The assembly of stabilizing and control suraces on the tail of an airplane.
Term
The rudder
Definition
The upright control surface attached to the vertical stavilizer to control yaw.
Term
Elevators
Definition
The horizontal control surfaces attached to the horizontal stavilizer to control pitch.
Term
Landing gear
Definition
Permits ground taxi operation and absorvs the shock encountered during takeoff and landing.
Term
The engine
Definition
Provides the thrust necessary for powered flight.
Term
What engine does a T-34C have?
Definition
a PT6A-25 turboprop engine.
Term
Center of gravity
Definition
The point at which all weight is considered to be concentrated and about which all forces and moments (yaw, pitch and roll) are measured. (Theoretically the airplane will balance if suspended at the center of gravity)
Term
The longitudinal axis
Definition
Passes from the nose to the tail of the airplane. movement of the lateral axis around the longitudinal axis is called roll.
Term
The lateral axis
Definition
Passes from wingtip to wingtip. movement of the longitudinal axis around the lateral axis is called pitch.
Term
The vertical axis
Definition
Passes vertically through the center of gravity. Movement of the longitudinal axis around the vertical axis is called yaw.
Term
Wingspan (b)
Definition
The length of a wing, measured from wingtip to wingtip.(refers to entire wing and not just one side)
Term
Chordline
Definition
An infinitely long, straight line which passes through its leading and trailing edges.
Term
Chord
Definition
A measure of the width of an airfoil.
Term
Root chord (Cr)
Definition
The chord at the wing centerline.
Term
Tip chord (Ct)
Definition
the chord at the wingtip.
Term
Wing Area (S)
Definition
The apparent surface area of a wing from wingtip to wingtip. (S = bc)
Term
Average chord (c)
Definition
The average of every chord from the wing root to the wingtip.
Term
Taper
Definition
The reduction in the chord of an airfoil from root to tip.
Term
Taper ratio
Definition
The ratio of the tip chord to the root chord. ( taper ratio = Ct / Cr )
Term
Sweep angle
Definition
is the angle between the lateral axis and a line drawn 25% aft of the leading edge.
Term
Aspect ratio (AR)
Definition
The ratio of the wingspan to the average chord. An aircraft with a high aspect rato such as a glider would have a long, slender wing. a low aspect ratio indicates a short, stubby wing, such as on a high performance jet. AR = b/c
Term
Wing loading (WL)
Definition
The raio of an airplane's weight to the surface area of its wings. WL = W/S
Term
Angle of incidence
Definition
The angle between the airplane's longitudinal axis and the chordline of the wing.
Term
Dihedral angle
Definition
The angle between the spanwise inclination of the wing and the lateral axis. (the upward slope of the wing when viewed from the front)
Term
What variety of wing has no external bracing?
Definition
Full cantilever
Term
What control surfaces are attached to the wing?
Definition
Ailerons.
Term
What type of construction is used in the fuselage of the T-34C?
Definition
Semi-monocoque fuselage consisting of stringers, transverse frame members and the skin.
Term
What control surfaces are attached to the empennage?
Definition
Rudder and elevator.
Term
What control surface is used for longitudinal control?
Definition
The elevator.
Term
What is the primary source of directional control?
Definition
The rudder.
Term
Define airplane center of gravity
Definition
The point at which all weight is considered to be concentrated.
Term
List the three airplane axes and the motions that occur about each.
Definition
longitudinal - roll
lateral - pitch
directional - yaw
Term
Steady airflow
Definition
Exists if at every pint in the airflow static pressure, density, temperature and velocity remain constant over time.
Term
Streamline
Definition
The path that air particles follow in steady airflow.
Term
Stremtube
Definition
A collection of many adjacent streamlines.
Term
Dynamic pressure (q)
Definition
The pressure of a fluid resulting from its motion. q = 1/2 row v^2
Term
Total pressure (Pt)
Definition
The sum of static and dynamic pressure. (Total pressure remains constant within a closed system)
Term
Pitot static system
Definition
A system consisting of a pitot tube, a static pressure port, and a device that determines the difference, used principally in order to calculate dynamic pressure.
Term
Indicated Air Speed (IAS)
Definition
The instrument indication of the dynamic pressure the airplane is exposed to during flight.
Term
Calibrated airspeed (CAS)
Definition
When indicated airspeed is corrected for instument error.
Term
Compressibility error
Definition
Caused by the ram effect of air in the pitot tube resulting in higher than normal airspeed indications at airspeeds approaching the speed of sound.
Term
Equivalent airspeed (EAS)
Definition
The true airspeed at sea level on a standard day that produces the same dynamic pressure as the actual flight condition. It is found by correcting calibrated airspeed for compressibility error.
Term
True airspeed (TAS)
Definition
The actual velocity at which an airplane moves through an air mass. It is found by correcting EAS for density.
Term
Ground speed
Definition
The airplane's actual speed over the ground.It is TAS corrected for the movement of the air mass (wind) (GS = TAS - headwind, GS = TAS + Tailwind)
Term
Mach Number (M)
Definition
The ratio of the airplane's true airspeed to the local speed of sound: M = TAS/LSOS
Term
Critical mach number (Mcrit)
Definition
The free airstream Mach number that produces the first evidence of local sonic flow.
Term
State the continuity equation. What are the variables in the equation? When may the dinsity variable be cancelled?
Definition
row1 A1 V1 = row2 A2 V2.
row is density, A is the cross sectional area, and V is the velocity. Row may be cancelled if altitude remains constant and airflow is subsonic.
Term
According to the continuity equation, if the velocity of an incompressible fluid is to double, what must happen to the cross sectional area of the flow?
Definition
it must be reduced by 1/2.
Term
State Bernoulli"s equation. Under what conditions does total pressure remain constant? If Pt is constant, how do q and Ps relate?
Definition
Pt = Ps + q. Total pressure remains constant in a closed system. Ps is inversely related to q, if Pt is constant.
Term
Describe how the pitot static system works using Bernoulli's equation.
Definition
The pitot static system consists of a total pressure sensor, the pitot tube; a static pressure sensor, the static port; and a mechanism that determines the difference between the two in order to calculate dynamic pressure which is displayed in the cockpit as indicated airspeed (q = Pt - Ps)
Term
For a given altitude, what is true about the pressure in the static pressure port of the airspeed indicator?
Definition
For a given altitude, the pressure in the static pressure port of the airspeed indicator is constant for all airspeeds and all angles of attack.
Term
Define IAS and TAS, what is the equation relating the two?
Definition
IAS is the instrument indication for the dynamic pressure the aircraft is creating during flight. True airspeed (TAS) is the actual velocity at which an aircraft moves through an air mass. TAS = sqrt(row0/row) * IAS
Term
When will IAS equal TAS?
Definition
when row = row0
Term
How do IAS and TAS vary with increases in altitude?
Definition
As altitude increases with a constant IAS, TAS will increase.
Term
A T-45 is climbing at a constant 350 KIAS. What would be the effect on Mach Number as it climbs? Why?
Definition
Mach number increases because TAS increases and the local speed of sound decreases.
Term
Pitch attitude
Definition
The angle between an airplane's longitudinal axis and the horizon.
Term
Flight pathThe path described by an airplane's center of gravity as it moves through an air mass.
Definition
Term
Relative wind
Definition
The airflow the airplane experiences as it moves throught the air. It is equal in magnitude and opposite inm direction to the flight path.
Term
Angle of attack (alpha)
Definition
The angle between the relative wind and the chordline of an airfoil.(AOA)
Term
mean camber line
Definition
Is a line drawn halfway between the upper and lower surfaces of the wing.
Term
positive camber
Definition
when the mean camber line is above the chordline
Term
negative camber
Definition
when the mean camber line is below the chordline.
Term
symmetric airfoil
Definition
When the mean camber line is coincident with the chordline.
Term
airfoil thickness
Definition
the height of the airfoil profile.
Term
aerodynamic center
Definition
the point along the chordline around which all changes in the aerodynamic force take place.
Term
spanwise flow
Definition
airflow that travels along the span of the wing, parallel to the leading edge. (normally from the root to the tip) This airflow is not accelerated over the wing and therefore produces no lift.
Term
chordwise flow
Definition
air flowing at right angles to the leading edge of an airfoil. it is the only airflow that produces lift.
Term
aerodynamic force
Definition
The net force that results from pressure and friction distribution over an airfoil.
Term
Lift (L)
Definition
The component of the aerodynamic force acting perpendicular to the relative wind.
Term
Drag (D)
Definition
The component of the aerodynamic force acting prallel to and in the same direction as the relative wind.
Term
boundary layer
Definition
That layer of airflow over a surface that demonstrates local airflow retardation dur to viscosity.
Term
Laminar flow
Definition
When the air moves smoothly along in streamlines. Produces very little friction but is easily separated from the surface.
Term
Turbulent flow
Definition
When the streamlines break up and the flow is disorganized and irregular.
Term
favorable pressure gradient
Definition
assits the boundary later in adhering to the surface by maintaining its high kinetic energy.
Term
adverse pressure gradient
Definition
impedes the flow of the boundary later.
Term
Stall
Definition
A condition of flight in which an increase in AOA results in a decrease in Cl.
Term
ClmaxAOA
Definition
stalling angle of attack.
Term
Slot
Definition
Allow high static pressure air beneath the wing to be accelerated through a nozzle and injected into the boundary layer on the upper surface of the airfoil.
Term
Fixed slots
Definition
gaps located at the leading edge of a wing that allow air to flow from below the wing to the upper surface.
Term
slats
Definition
moveable leading edge sections used to form automatic slots.
Term
plain flap
Definition
a simple hinged portion of the trailing edge that is forced down into the airstream to increase the camber of the airfoil.
Term
split flap
Definition
a plate deflected fro the lower surface of the airfoil.
Term
slotted flap
Definition
similar to plain flap, but moves away from the wing to open a narrow slot between the flap and wing for boundary layer control.
Term
fowler flap
Definition
used extensively on larger airplanes, it moves down, increasing the camber and aft causing a significant increase in wing area as werll as opening one or more slots for bound layer control.
Term
leading edge flaps
Definition
devices that change the wing camber at the leading edge of the airfoil.
Term
Geometric twist
Definition
a decrease in angle of incidence from wing root to wingtip.
Term
aerodynamic twist
Definition
a gradual change in airfoil shape that increases ClmaxAOA to a higher value near the tip than at the root. (T-34)(A decrease in camber from root to tip)
Term
stall strip
Definition
a strip mounted on the leading edge of the root section to induce a stall at the wing root.
Term
Stall fence
Definition
redirects airflow along the chord.
Term
Stall Pattern/Wing design
Definition
rectangular wing-root stall tend-low speed & light weight airplanes/
highly tapered wing-tip stall tend./
swept wing-tip stall tend-high speed acft/
elliptical wing-even stall progression/
moderate taper wing-even stall progression.
Term
Thrust required (Tr)
Definition
Amt of thrust required to overcome drag.
Term
power required (Pr)
Definition
The amt of pwr required to produce thrust required (Tr)
Term
thrust availiable (Ta)
Definition
the amt of thrust produced at a given throttle setting(and velocity and density)
Term
Power availiable (Pa)
Definition
amt of pwr engines produce at given throttle setting (and velocity and density).
Term
shaft horsepower (SHP)
Definition
engine output
Term
thrust horsepower (THP)
Definition
propeller output
Term
propeller efficency
Definition
the ability of the prop to turn engine output into thrust.
Term
thrust excess (Te)
Definition
when thrust availiable is greater than thrust required
Term
Power excess (Pe)
Definition
when availiable pwr is greater than required pwr.
Term
2 types of drag
Definition
parasite and induced drag
Term
parasite drag
Definition
form drag, friction drag and interference drag. all drag not associated with production of lift.
Term
form drag
Definition
caused by airflow separation from sfc and low pressure wake created by separation.
Term
interference drag
Definition
caused by mixing of streamlines btwn components
Term
friction drag
Definition
caused by friction forces at sfc of acft due to viscosity of air.
Term
induced drag
Definition
the portion of total drag associated with production of lift.
Supporting users have an ad free experience!