basic aerodynamics

AERODYNAMICS

AERODYNAMICSBernoulli's PrincipalLift & Lift EquationStall & Stall CharacteristicsFactors Affecting PerformanceClimbing PerformanceGliding Performance

Turning PerformanceTakeoff & Landing PerformanceStabilityVg DiagramTorque & P FactorSpins

BERNOULLIS PRINCIPALBernoullis principal is best described using which effect?

a. Coriolis effect.b. Venturi effect.c. Neither a nor b

BERNOULLIS PRINCIPAL Bernoullis principal is best described using which effect?

VENTURI EFFECT

BERNOULLIS PRINCIPALConcerning the Venturi effect, as the cross-sectional area of a tube is reduced, the velocity of the airflow through the tube must--a. Decreaseb. Increasec. Remain the same

BERNOULLIS PRINCIPALConcerning the Venturi effect, as the cross-sectional area of a tube is reduced, the velocity of the airflow through the tube must--

As the velocity of the air moving through a venturi increases--

a. Static pressure decreasesb. Static pressure incresesc. Static pressure is difficult to measure and therefore an increase or decrease is considiered neglible.BEROUNILLIS PRINCIPAL

BEROUNILLIS PRINCIPALAs the velocity of the air moving through a venturi increases--

BEROUNILLIS PRINCIPALStatic pressure is defined as--a. Compressed air containing positively charged ions.b. The atmospheric pressure of the air through which an airplane is flying.c. The pressure of a fluid resulting from its motion.

BEROUNILLIS PRINCIPALStatic pressure is defined as--

The atmospheric pressure of the air through which an airplane is flying.

BEROUNILLIS PRINCIPALDynamic pressure is defined as--a. Compressed air containing positively charged ions.b. The atmospheric pressure of the air through which the airplane is moving.c. The pressure of a fluid resulting from its motion.d. None of the above.

BEROUNILLIS PRINCIPALDynamic pressure is defined as--

The pressure of a fluid resulting from its motion.

LIFTRelative wind is--a. The air in motion that is equal and opposite the flight path velocity of the airfoil.b. The angle measured between the resultant relative wind and the chord.c. The angle between the airfoil chord line and the longitudinal axis of the airplane.d. None of the above.

LIFTRelative wind is-

The air in motion that is equal to and opposite the flight-path velocity of the airfoil.

LIFT Angle of Attack is the angle measured between the resultant relative wind and the chord

a. Trueb. False

LIFTAngle of Attack is the angle measured between the resultant relative wind and the chord

a. Trueb. False

LIFTCenter of Pressure is defined as:a. The point along the mean camber line where all aerodynamic forces are considered to act.b. The point along the chord line of an airfoil through which lift is considered to act. c. The point along the chord line on an airfoil through which all aerodynamic forces are considered to act.

LIFTCenter of Pressure is defined as: The point along the chord line on an airfoil through which all aerodynamic forces are considered to act.

LIFT Aerodynamic center is the point along the chord line of an airfoil through which all aerodynamic forces are considered to act.

a. Trueb. False

LIFTLift is defined as--

a. the component of the total aerodynamic force that acts at right angles to drag.b. the component of the total aerodynamic force that acts at right angles to the RRW.c. Neither a nor b are true.

LIFTLIFT

The component of the total aerodynamic force that acts at right angles to the resultant relative wind

LIFT The two factors that most affect the coefficient of lift and the coefficient of drag are:a. weight & balanceb. thrust & air densityc. shape of the airfoil & angle of attack

LIFT The two factors that most affect the coefficient of lift and the coefficient of drag are:

Shape of the airfoil & angle of attack

LIFT L= CL 1/2p S V2L ~ Lift forceCL ~ Coefficient of liftp(rho) ~ density of the air in slugsS ~ total wing area in square feetV ~ airspeed (in feet per second)

DRAGD= CD 1/2p S V2D ~ Drag forceCD ~ Coefficient of liftp(rho) ~ density of the air in slugsS ~ total wing area in square feetV ~ airspeed (in feet per second)

DRAGTWO TYPES OF DRAG:

PARASITE

INDUCED

DRAGPARASITIC DRAG

Drag that is produced by non-lifting portions of the airframe. There are 3 components of parasitic drag:

Form D.rag

Skin Friction Drag.

Interference Drag.

DRAGFORM DRAG--

The portion of drag that is generated because of the shape of the airplane. Generated in the turbulent areas of airflow where slipstream does not conform to aircraft shape.Varies directly with the airspeed.

DRAGSKIN-FRICTION DRAG--

The boundary layer air creates stagnant layer of air molecules.Drag is created when the slipstream comes in contact with this stagnant flow. Varies directly with the airspeed.

DRAGINTERFERENCE DRAG--

Created by the collision of airstreams.Causes eddy currents, restrictions, and turbulence to smooth flow. Varies directly with the airspeed.

DRAGINDUCED DRAG

Drag created as a result of the production of lift.Induced drag creates wingtip vortices and vertical velocities. Varies inversely with the airspeed.

DRAGTotal drag is that component of the total aerodynamic force parallel to the ___________ that tends to retard the motion of the aircraft.a. chord lineb. center of pressurec. relative windd. none of the above

DRAGTotal drag is that component of the total aerodynamic force parallel to the RELATIVE WIND that tends to retard the motion of the aircraft.

DRAGAn airfoil with a higher lift to drag ratio is more efficient than an airfoil with a lower lift to drag ratio.

a. Trueb. False

STALL & STALL CHARACTERISTICSA stall occurs when:a. The airplane enters the region of reverse command.b. The airplane is flown above CL max.c. The airfoil is flown at an angle of attack greater than that for maximum lift.d. None of the above.

STALL & STALL CHARACTERISTICSA stall occurs when:

The airfoil is flown at an angle of attack greater than that for maximum lift.

STALL & STALL CHARACTERISTICS An aerodynamic stall occurs when an increase in the angle of attack results in a loss of lift and is due to:a. low airspeedb. density altitudec. seperation of boundary-layer air.

STALL & STALL CHARACTERISTICS An aerodynamic stall occurs when an increase in the angle of attack results in a loss of lift and is due to:

Separation of Boundary Layer Air

STALL & STALL CHARACTERISTICS When the boundary layer separates, turbulence occurs between the boundary layer and the surface of the wing. This results in--

a. an increase in dynamic pressure above the wing.b. an increase in the static pressure above the wing.c. Neither a or b

STALL & STALL CHARACTERISTICS When the boundary layer separates, tubulence occurs between the boundary layer and the surface of the wing. This results in--

An increase in the static pressure above the wing

STALL & STALL CHARACTERISTICS Increasing the AOA beyond the boundary-layer separation point will result in--a. a further increase in lift.b. the boundary-layer separation point moving forward on the airfoil.c. a decreased top surface area of the wing available to produce lift.d. b and c

STALL & STALL CHARACTERISTICS Increasing the AOA beyond the boundary-layer separation point will result in--

The boundary-layer separation point moving forward leaving a smaller wing surface area available to develop lift.

STALL & STALL CHARACTERISTICS Designing the wing to stall from the wingtips progressively inboard toward the root section is a desirable airplane design characteristic.

a. Trueb. False

STALL & STALL CHARACTERISTICS Three reasons why airplane wings are designed to stall root first:Impending stall warning over elevator

Lessens severity by preventing sudden stall

Allows better lateral control

STALL & STALL CHARACTERISTICSDefine Geometric Twist--a. A method used to counteract torque.b. That stupid lemon they always ruin your Corona with.c. The twist of an airfoil having different geometric angles of attack at different spanwise locations.

STALL & STALL CHARACTERISTICSGEOMETRIC TWISTThe twist of an airfoil having different geometric angles of attack at different spanwise locations. Root has greater angle of incidence than tipRoot operates at an aerodynamically lower of attack.

STALL & STALL CHARACTERISTICSAerodynamic Twist is accomplished by--a. Varying the angle of incidence along the wing.b. The addition of leading-edge slots.c. Designing different values of CL maximum along the span of the wing.d. Adding full top rudder during the execution of an aileron roll.

STALL & STALL CHARACTERISTICSAerodynamic Twist is accomplished by--

Designing different values of CL maximum along the span of the wing.

STALL & STALL CHARACTERISTICS

WITH 100% ACCURACY, STATE THE PURPOSE OF THE STALL STRIP

STALL & STALL CHARACTERISTICS The stalling speed of an airplane is affected by its weight.

a. Trueb. False

STALL & STALL CHARACTERISTICSThe stalling speed of an airplane is affected by its weight.

a. True b. False

STALL & STALL CHARACTERISTICSTHE STALL-SPEED EQUATION

Vs = 2W CL p S

STALL & STALL CHARACTERISTICS Altitude does not affect the stall speed of an aircraft.a.Trueb.False


Altitude does not affect the stall speed of an aircraft.a.Trueb.False


Vs = 2W CL p S

STALL & STALL CHARACTERISTICSAs flaps are lowered, CL MAXIMUM _____________.

a. Decreasesb. Increasesc. Becomes Cmax

STALL & STALL CHARACTERISTICSAs flaps are lowered, CL MAXIMUM _____________.

a. Decreasesb. Increasesc. Becomes Cm


Vs = 2W CL p S

STALL & STALL CHARACTERISTICSLoad Factor is the lift the aircraft is required to develop, divided by the weight of the aircraft (n = L/W). An increase in load factor will result in an increase in stall speed.

a. Trueb. False


TRUE

Vs = 2nW Clmax p S


If stalling speed is directly proportional to the the square root of the load factor then . . . .


What is Vs for a C-12 in a 60 degree bank?

Accelerated Stall Speed = Vs n

STALL & STALL CHARACTERISTICS The airplane can fly slower with more thrust applied.

a. Trueb. False

STALL & STALL CHARACTERISTICSTRUE

Vs = 2(nW - T sin a ) Clmax p S

STALL & STALL CHARACTERISTICSTHINGS TO REMEMBER ABOUT THRUSTThe angle between thrust vector & RW is the AOAThe thrust vector is considered to act along chordThere is a vertical component of thrust that acts parallel to lift and is expressed as T sin a.L + T sin a - nW = 0The vertical component of thrust reduces stall speed

PERFORMANCE FACTORSIdentify the factor that most affects an aircrafts ability to climb.

a. Dragb. Liftc. Excess Powerd. Thrust

PERFORMANCE FACTORSIdentify the factor that most affects an aircrafts ability to climb.

EXCESS POWER

PERFORMANCE FACTORSDuring climb, lift operates perpendicular to:

a. drag.b. the flight path.c. weightd. thrust

PERFORMANCE FACTORSDuring climb with the flight path inclined, lift is acting partially rearward resulting in an increase in--

a. parasite dragb. profile dragc. induced drag

PERFORMANCE FACTORSWeight always acts perpendicular to the earths surface. With this in mind, which statement is correct during climb?a. Thrust must overcome drag and gravity.b. Weight is not perpendicular to the RW.c. Weight acts perpendicular to thrustd. Both a & be. Both b & c

PERFORMANCE FACTORSPOWER REQUIRED FOR CLIMB

T = D + W sin yT ~ ThrustD ~ DragW ~ Weightsin y ~ angle of climb

PERFORMANCE FACTORSBest angle of climb speed (Vx) listed in the operators manual--

a. provides the best obstacle clearance performance.b. is a safe best angle of climb speed.c. is greater than the true best angle of climb speed.d. a & be. b & c

PERFORMANCE FACTORSFACTORS AFFECTING ANGLE OF CLIMB

ALTITUDE

WEIGHT

WIND

PERFORMANCE FACTORSFACTORS AFFECTING ANGLE OF CLIMB(ALTITUDE)Thrust available (TA) decreases with increase in altitude.Thrust required (TR) remains same at all altitudes.sin y must decrease to compensate for decreasing TA

ABSOLUTE CEILINGTA = TR and sin y = 0

PERFORMANCE FACTORS

FACTORS AFFECTING ANGLE OF CLIMB(WEIGHT) An increase results in an increase of TR. An increase results in decrease of excess TA. An increase results in shallower angle of climb.

PERFORMANCE FACTORSFACTORS AFFECTING ANGLE OF CLIMB(WIND) Affects the angle the aircraft climbs over the ground. Affects the horizontal distance covered across ground.

PERFORMANCE FACTORSFACTORS AFFECTING RATE OF CLIMB

ALTITUDE

WEIGHT

PERFORMANCE FACTORSFACTORS AFFECTING RATE OF CLIMB(ALTITUDE)HPA decreases with increase in altitude.HPR remains relatively constant.ROC decreases with increase in altitude. ABSOLUTE CEILINGHPA = HPR & ROC = 0 FEET

PERFORMANCE FACTORSFACTORS AFFECTING RATE OF CLIMB(WEIGHT)

Increase in weight results in increase in HPR.Increase in weight results in decrease in excess HPA.

PERFORMANCE FACTORSFACTORS AFFECTING GLIDES

An airplane will descend when--

a. Weight exceeds lift.b. Lift exceeds thrust.c. Thrust exceeds drag.d. All of the above.

PERFORMANCE FACTORSFACTORS AFFECTING GLIDESAn airplane will descend when--

a. Weight exceeds lift.b. Lift exceeds thrust.c. Thrust exceeds drag.d. All of the above.

PERFORMANCE FACTORSFACTORS AFFECTING GLIDESWhat affect does weight have on the maximum-glide distance? a. Increase in weight shortens gliding distance. b. Increase in weight lengthens gliding distance c. Weight has no affect on gliding distance.


Maximum gliding distance is attained--a. At Clmasb. At its minimum glide angle.c. At its maximum glide angle.d. None of the above.

PERFORMANCE FACTORSFACTORS AFFECTING GLIDESMinimum glide angle corresponds to the same angle that will produce--a. Clmaxb. Vrefc. L/Dmaxd. All of the above

PERFORMANCE FACTORS

PERFORMANCE FACTORSTURNING FORCESThe force(s) that turns the aircraft is--a. Centrifugal force.b. Centripetal force.c. The lift force.d. All of the above.

PERFORMANCE FACTORSTURNING FORCESThe apparent increase in weight during a turnis caused by which force(s)?a. Centripetal b. Liftc. Centrifugal

PERFORMANCE FACTORSTURNING FORCESDuring the turn, lift is divided into two components that act at right angles to each other.

Horizontal Componentof LiftVertical Componentof Lift

PERFORMANCE FACTORSTURNING FORCESThe force opposing the vertical component is __________, and the force opposing the horizontal component is _________.a. drag, thrustb. centripetal, centrifugal c. centrifugal, centripetald. weight, centrifugal

PERFORMANCE FACTORSTURNING FORCES

The force opposing the vertical component is weight, and the force opposing the horizontal component is centrifugal.

PERFORMANCE FACTORS Three Factors That Limit Radius of Turn

AERODYNAMIC LIMIT OF PERFORMANCE

STRUCTURAL LIMIT OF PERFORMANCE

POWER LIMIT OF PERFORMANCE

PERFORMANCE FACTORS Three Factors That Limit Radius of TurnAERODYNAMICOccurs when airplane turns at its stall velocity

STRUCTURALOccurs when aircraft turns at its max load limit

POWERTR cannot overcome induced drag

PERFORMANCE FACTORS

Banking an aircraft into a level turn does not change the amount of lift.

Division of lift reduces amount of lift to overcome weight.

Increasing AOA increases total lift and until vertical component equals weight again.

PERFORMANCE FACTORSTAKEOFF & LANDINGWhen close to runway the airplane experiences ground effect. This phenomenon--a. is a cushion of air.b. is cancelled out with approach flaps.c. reduces induced drag.d. a & c

PERFORMANCE FACTORS Ground Effect Reduces Induced Drag:

1.4% @ 1 wingspan

23.5% @ 1/4 wingspan

47.6% @ 1/10 wingspan

PERFORMANCE FACTORSTAKEOFF & LANDINGDuring takeoff roll the aircraft must overcome the sum of the horizontal forces in order to accelerate. These forces are:a. Dragb. Frictionc. Propeller slippaged. All of the abovee. a & b

PERFORMANCE FACTORSTAKEOFF & LANDINGDuring takeoff roll the aircraft must overcome the sum of the horizontal forces in order to accelerate. These forces are:

DRAG &FRICTION

PERFORMANCE FACTORSTAKEOFF & LANDINGFor a given altitude and RPM, the thrust from a propeller-driven airplane ___________ as velocity increases during the takeoff roll.a. remains unchangedb. decreasesc. increases

PERFORMANCE FACTORSTAKEOFF & LANDINGFor a given altitude and RPM, the thrust from a propeller-driven airplane decreases as velocity increases during the takeoff roll.

PERFORMANCE FACTORSTAKEOFF & LANDING

Takeoff distance is directly proportional to takeoff velocity squared.

Takeoff velocity is a function of stalling speed.

Takeoff speed is 1.2 x Vso

Flaps 40%Improve L/D ratioIncrease CLmaxDecrease VsDecrease VlofDecrease Takeoff Distance

PERFORMANCE FACTORS1. An increase in Density Altitude results in an increase in takeoff distance. 2. This increase is due to the additional IAS required to develop the same amount of lift required at a lower Density Altitude.

a. 1 & 2 are correct.b. neither 1 nor 2 are correct.c. only 1 is correctd. only 2 is correct

PERFORMANCE FACTORSTAKEOFF & LANDINGForces that comprised acceleration during takeoff are reversed for landings.

Deceleration forces are reversed.

Primary concern is dissipation of kinetic energy.

PERFORMANCE FACTORSTAKEOFF & LANDINGResidual thrust of the propellers must be overcome during landing. This is overcome with:a. Flapsb. Speed brakesc. Reverse thrustd. Braking

PERFORMANCE FACTORSTAKEOFF & LANDINGResidual thrust of the propellers must be overcome during landing. This is overcome with:

REVERSE THRUST

PERFORMANCE FACTORSTAKEOFF & LANDINGAerodynamic braking creates a net deceleration force by:a. Adding more flat-plate drag surface area to the slipstream. b. Increasing induced drag.c. Shifting weight of airplane to the tires and thereby increasing rolling friction.


The net deceleration force of aerodynamic braking is most effective--a. During the last half of the landing roll.b. During the first half of the landing roll.c. Throughout the entire landing roll.


The net deceleration force of wheel braking is most effective--a. During the last half of the landing roll.b. During the first half of the landing roll.c. Throughout the entire landing roll.

PERFORMANCE FACTORSTAKEOFF & LANDINGThe net deceleration force of wheel braking is most effective--a. During the last half of the landing roll.b. During the first half of the landing roll.c. Throughout the entire landing roll.

PERFORMANCE FACTORSTAKEOFF & LANDINGWhich deceleration force is the most effective during landing?a. Aerodynamic brakingb. Wheel braking (friction)c. Reverse thrust

PERFORMANCE FACTORSTAKEOFF & LANDINGWhich deceleration force is the most effective during landing?

PERFORMANCE FACTORSTAKEOFF & LANDINGThe speed at which hydroplaning occurs is dependent upon:a. Flap settingb. Aircraft weightc. Water depthd. Tire pressuree. Tread design


HYDROPLANING SPEED

TP (9)

INCREASE LANDING

NO WINDS

NO FLAPS

NO BRAKES

NO REVERSE

HYDROPLANING

HIGH WEIGHT

DECREASE LANDING

HEADWIND

FULL FLAPS

FULL BRAKING

FULL REVERSE

DRY RUNWAY

LOW WEIGHT

STABILITYTHREE TYPES OF STABILITY

Positive Static Stability

Negative Static Stability

Neutral Static Stability

STABILITYAn object possesses _______ _______ _______ if it tends to return to its equilibrium position after it has been moved.a. positive dynamic stabilityb. positive static stabilityc. desirable static stability

STABILITY

POSITITVE STATIC STABILITY

An object possesses positive static stability if it tends to return to its equilibrium position after it has been moved.

STABILITYIf an object that has been displaced tends to return to its equilibrium position through a series of diminishing oscillations, it is said to have--a. Negative static and negative dynamic stability.b. Neutral static and neutral dynamic stability.c. Positive static and positive dynamic stability.

STABILITYThe overall static stability of the aircraft along the longitudinal axis depends on the position of the Center of Gravity ( CG) in relation to the Aerodynamic Center (AC).

STABILITYIn order for positive static and dynamic stability to exist along the longitudinal axis,which of the following statements is true?a. The AC must be ahead of the CGb. The AC must be behind of the CGc. The AC and CG must always be the same

STABILITYWhich of the following methods is employed to improve stability about the longitudinal axis?

a. Symmetrical horizontal stabilizerb. Differential Aileronsc. Dihedral

STABILITYWhich of the following methods is employed to improve stability about the longitudinal axis?

DIHEDRAL

TORQUETorque is the rotation of the aircraft in a direction opposite the rotation of the propellers. It is best described by:

a. Newtons first law of motion.b. The coriolis effectc. Newtons third law of motion.

P FACTORP Factor is most noticeable--

a. during takeoff roll.b. during long flights with a inoperative relief tube.c. during high angles of attack and high power settings.

SLIPSTREAM ROTATIONSlipstream rotation is caused by the spiraling airflow from the propellers.

a. Trueb. False

SLIPSTREAM ROTATIONThe pilot must correct for slipstream rotation by--

a. Adding left aileron.b. Reducing power on #1 enginec. Adding the appropriate amount of rudder to prevent the yaw.

SPINS

A spin is a stall that is aggravated with a turning & yawing condition.

SPIN ONE WING STALLSYAW BEGINSROLL BEGINSSPIN

SPIN RECOVERYPOWEROFFFULLRUDDERFORWARDYOKEAILERONSNEUTRALRECOVERY

AERODYNAMICS

THE END

basic aerodynamics

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