Aerodynamics I Flashcards

Terms Definitions
shaft horsepower (SHP)
engine output
ClmaxAOA
stalling angle of attack.
 
 
Energy
 
 
 
Any source of usable power
 
 
Rudder
 
 
A control surface on fixed-wing aircraft, usually mounted at aft ending of the fuselage sticking up (like a dorsal fin), that controls yaw (heading), and is controlled by the pedals;
General Gas Law
P = (row)rt
 
 
 
Aerodynamics
 
The branch of physical science concerned with the reactions caused by the relative motion between a solid body and the surrounding air.
 
 
Bernoulli's Equation
 
In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.
 
 
Leading Edge
 
 
Forward edge of an airfoil
 
 
Airfoil
 
 
Section of a wing, rudder, aileron, or rotorblade used for testing reactions from the air through which it moves.
Standard atmosphere
29.92 in HG/1013.25 mb59F/15C3.57F/2C per 1000 ft..0024 slugs/ft^3 / 1.225 g/l661.7 kts/ 340.4 m/s
Force
Mass times acceleration. F = ma
Vector
A quantity that represents magnitude AND direction. Commonly used to represent displacement, velocity, acceleration or force.
Equilibrium
The absence of acceleration, either linear or angular.
 
 
Weight
 
 
The force of gravity acting on an object. The weight force pulls an aircraft toward the Earth and must be overcome by a combination of lift and thrust.
 
 
Wing Area
 
 
In general, a greater wing area means better low-speed maneuverability and lower takeoff and landing speeds.
 
 
Slug
 
A unit of mass associated with Imperial units. It is a mass that accelerates by 1ft/second squared when a force of one pound-force (lbf) is exerted on it. Therefore a slug has a mass of 32.17405 pound-mass or 14.5939 kg.
 
 
Steady Descent
 
 
Going down at a constant rate
Tip chord (Ct)
the chord at the wingtip.
Temperature
A measure of the average random kinetic energy of air particles.
parasite drag
form drag, friction drag and interference drag. all drag not associated with production of lift.
Density Altitude
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.
What control surfaces are attached to the wing?
Ailerons.
Stall Pattern/Wing design
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.
Dihedral angle
The angle between the spanwise inclination of the wing and the lateral axis. (the upward slope of the wing when viewed from the front)
Flight pathThe path described by an airplane's center of gravity as it moves through an air mass.
Landing gear
Permits ground taxi operation and absorvs the shock encountered during takeoff and landing.
Slot
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.
 
 
Chord Line
 
 
The straight line drawn from a point on the top to a point on the base
 
 
Center of Gravity
 
 
The point within something at which gravity can be considered to act; in uniform gravity it is equal to the center of mass
 
 
Mach Number
 
 
Ratio of airspeed to the local speed of sound (Mach 1 is the speed of sound under current atmospheric condition)
Velocity
The speed and direction of a body's motion, the rate of change of position.
form drag
caused by airflow separation from sfc and low pressure wake created by separation.
Stall
A condition of flight in which an increase in AOA results in a decrease in Cl.
aerodynamic center
the point along the chordline around which all changes in the aerodynamic force take place.
When will IAS equal TAS?
when row = row0
aerodynamic force
The net force that results from pressure and friction distribution over an airfoil.
Lift (L)
The component of the aerodynamic force acting perpendicular to the relative wind.
Energy
A scalar measure of a body's capacity to do work. TE = PE + KE
Chord
A measure of the width of an airfoil.
Fuselage
The basic structure of the airplane to which all other components are attached.
Viscosity
A measure of the air's resistance to flow and shearing. Air viscosity incerases with an increase in temperature.
induced drag
the portion of total drag associated with production of lift.
Angle of incidence
The angle between the airplane's longitudinal axis and the chordline of the wing.
 
 
Wing Tip
 
 
The part of the wing that is most distant from the fuselage of a fixed-wing aircraft
 
 
Lift to Drag Ratio
 
 
The amount of lift generated by a wing or vehicle, divided by the drag it creates by moving through the air
Geometric twist
a decrease in angle of incidence from wing root to wingtip.
adverse pressure gradient
impedes the flow of the boundary later.
aerodynamic twist
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)
Mach Number (M)
The ratio of the airplane's true airspeed to the local speed of sound: M = TAS/LSOS
Wingspan (b)
The length of a wing, measured from wingtip to wingtip.(refers to entire wing and not just one side)
Full Monocoque fuselage
Extremely light and strong because it consists of only a skin shell which is highly stressed but almost impossible to repair if damaged.
boundary layer
That layer of airflow over a surface that demonstrates local airflow retardation dur to viscosity.
Pressure altitude (PA)
The height above the standard datum plane.
Trimmed flight
Exists when the sum of all moments around the center of gravity is equal to zero.
 
 
Center of Pressure
 
 
The point on a body where the total sum of the aerodynamic pressure field acts, causing a force and no momentum about that point.
Center of gravity
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)
Equilibrium Flight
Exists when the sum of all forces and the sum of all moments around the center of gravity are equal to zero.
Potential Energy
The avility of a body to do work because of its position or state of being. PE = mgh
Kinetic Energy
The ability of a body to do work because of its motion. KE = 1/2 mV^2
Critical mach number (Mcrit)
The free airstream Mach number that produces the first evidence of local sonic flow.
mean camber line
Is a line drawn halfway between the upper and lower surfaces of the wing.
Power availiable (Pa)
amt of pwr engines produce at given throttle setting (and velocity and density).
negative camber
when the mean camber line is below the chordline.
Dynamic pressure (q)
The pressure of a fluid resulting from its motion. q = 1/2 row v^2
thrust availiable (Ta)
the amt of thrust produced at a given throttle setting(and velocity and density)
List the three airplane axes and the motions that occur about each.
longitudinal - rolllateral - pitchdirectional - yaw
What type of construction is used in the fuselage of the T-34C?
Semi-monocoque fuselage consisting of stringers, transverse frame members and the skin.
How to add vectors
Place head of first vecotr to tail of second, draw third vector from tail of first to head of second.
How is DA used
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.
A T-45 is climbing at a constant 350 KIAS. What would be the effect on Mach Number as it climbs? Why?
Mach number increases because TAS increases and the local speed of sound decreases.
What change in air temperature occurs in the standard atmosphere from sea level through 66,000 ft?
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.
Define IAS and TAS, what is the equation relating the two?
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
Describe how the pitot static system works using Bernoulli's equation.
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)
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?
When the sum of the forces and moments about the center of gravity equal zero.
How do IAS and TAS vary with increases in altitude?
As altitude increases with a constant IAS, TAS will increase.
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