Aerodynamics

AERODYNAMICSAERODYNAMICS

AERODYNAMICSAERODYNAMICS Bernoulli's Principal Lift & Lift Equation Stall & Stall

Characteristics Factors Affecting

Performance Climbing Performance Gliding Performance

Turning Performance

Takeoff & Landing Performance

Stability Vg Diagram Torque & “P” Factor Spins

BERNOULLI’S PRINCIPALBERNOULLI’S PRINCIPAL

Bernoulli’s principal is best described using which effect?

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


Bernoulli’s principal is best described using which effect?

VENTURI EFFECT

BERNOULLI’S PRINCIPALBERNOULLI’S 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


Concerning 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.

BEROUNILLI’S PRINCIPALBEROUNILLI’S PRINCIPAL


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


Static 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.


Static pressure is defined as--

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


Dynamic 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.


Dynamic pressure is defined as--

The pressure of a fluid resulting from its motion.

LIFTLIFT

Relative 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.

LIFTLIFT

Relative wind is-

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

LIFTLIFT

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

a. Trueb. False

LIFTLIFT

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

a. Trueb. False

LIFTLIFTCenter 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.

LIFTLIFT

Center of Pressure is defined as:

The point along the chord line on an airfoil through which all aerodynamic

forces are considered to act.

LIFTLIFT

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

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

a. Truea. Trueb. False

LIFTLIFT

Lift 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

LIFT

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

resultant relative wind

LIFTLIFT

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

LIFTLIFT

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

Shape of the airfoil & angle of attack

LIFTLIFT

L= CL 1/2p S V2

L ~ Lift forceCL ~ Coefficient of lift

p(rho) ~ density of the air in slugsS ~ total wing area in square feetV ~ airspeed (in feet per second)

DRAGDRAG

D= CD 1/2p S V2

D ~ Drag forceCD ~ Coefficient of lift

p(rho) ~ density of the air in slugsS ~ total wing area in square feetV ~ airspeed (in feet per second)

DRAGDRAG

TWO TYPES OF DRAG:

– PARASITEPARASITE

– INDUCEDINDUCED

DRAGDRAG

PARASITIC 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.

DRAGDRAG

FORM 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.

DRAGDRAG

SKIN-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.

DRAGDRAG

INTERFERENCE DRAG--

– Created by the collision of airstreams.– Causes eddy currents, restrictions, and

turbulence to smooth flow. – Varies directly with the airspeed.

DRAGDRAG

INDUCED DRAG

Drag created as a result of the production of lift.

Induced drag creates wingtip vortices and vertical velocities.

Varies inversely with the airspeed.

DRAGDRAG

Total 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

DRAGDRAG

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

DRAGDRAG

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

a. Trueb. False

DRAGDRAG

An 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 STALL & STALL CHARACTERISTICSCHARACTERISTICS

A 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.


A stall occurs when:

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


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.


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


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


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


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


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.


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

a. True

b. FalseFalse


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


Define 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.


GEOMETRIC TWIST The twist of an airfoil having different

geometric angles of attack at different spanwise locations.

Root has greater angle of incidence than tip Root operates at an aerodynamically lower

of attack.


Aerodynamic 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.


Aerodynamic Twist is accomplished by--

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


WITH 100% ACCURACY, STATE THE PURPOSE OF THE

STALL STRIP


The stalling speed of an airplane is affected by it’s weight.

a. Trueb. False


The stalling speed of an airplane is affected by it’s weight.

a. True b. False


THE STALL-SPEED EQUATION

Vs = 2W

CL p S


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


As flaps are lowered, CL MAXIMUM

_____________.

a. Decreasesb. Increasesc. Becomes Cmax


As flaps are lowered, CL MAXIMUM _____________.

a. Decreasesb. Increasesc. Becomes Cm



Vs = 2W

CL p S


Load 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


The airplane can fly slower with more thrust applied.

a. Trueb. False


TRUE

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


THINGS TO REMEMBER ABOUT THRUST The angle between thrust vector & RW is the AOA The thrust vector is considered to act along chord There is a vertical component of thrust that acts

parallel to lift and is expressed as T sin a. L + T sin a - nW = 0 The vertical component of thrust reduces stall speed

PERFORMANCE FACTORSPERFORMANCE FACTORS

Identify the factor that most affects an aircraft’s ability to climb.

a. Dragb. Liftc. Excess Powerd. Thrust


Identify the factor that most affects an aircraft’s ability to climb.

EXCESS POWER


During climb, lift operates perpendicular to:

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


During climb, lift operates perpendicular to:

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


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

a. parasite dragb. profile dragc. induced drag


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

a. parasite dragb. profile dragc. induced drag


Weight always acts perpendicular to the earth’s 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


Weight always acts perpendicular to the earth’s 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


POWER REQUIRED FOR CLIMB

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


Best 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


Best 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 & b

e. b & c


FACTORS AFFECTING ANGLE OF CLIMB

ALTITUDE

WEIGHT

WIND

PERFORMANCE FACTORSPERFORMANCE 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


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.


FACTORS AFFECTING ANGLE OF CLIMB(WIND)

– Affects the angle the aircraft climbs over the ground.– Affects the horizontal distance covered across ground.


FACTORS AFFECTING RATE OF CLIMB

ALTITUDE

WEIGHT


FACTORS AFFECTING RATE OF CLIMB(ALTITUDE)

– HPA decreases with increase in altitude.

– HPR remains relatively constant.– ROC decreases with increase in altitude.

ABSOLUTE CEILING

HPA = HPR & ROC = 0 FEET


FACTORS AFFECTING RATE OF CLIMB(WEIGHT)

– Increase in weight results in increase in HPR.

– Increase in weight results in decrease in excess HPA.


FACTORS AFFECTING GLIDES

An airplane will descend when--

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


FACTORS AFFECTING GLIDESAn airplane will descend when--

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


FACTORS 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.



PERFORMANCE FACTORSPERFORMANCE FACTORSFACTORS AFFECTING GLIDES

Maximum gliding distance is attained--a. At Clmas

b. At it’s minimum glide angle.c. At it’s maximum glide angle.d. None of the above.



Maximum gliding distance is attained--a. At Clmas

b. At it’s minimum glide angle.c. At it’s maximum glide angle.d. None of the above.


FACTORS AFFECTING GLIDESMinimum glide angle corresponds to the same angle that will produce--a. Clmax

b. Vref

c. L/Dmax

d. All of the above



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


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


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


TURNING FORCESThe apparent increase in weight during a turnis caused by which force(s)?a. Centripetal b. Lift

c. Centrifugal

PERFORMANCE FACTORSPERFORMANCE FACTORSTURNING FORCES

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

Horizontal Component

of Lift

Vertical Component

of Lift

PERFORMANCE FACTORSPERFORMANCE FACTORSTURNING FORCES

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


TURNING FORCES

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


Three Factors That Limit Radius of TurnThree Factors That Limit Radius of Turn

AERODYNAMIC LIMIT OF PERFORMANCE

STRUCTURAL LIMIT OF PERFORMANCE

POWER LIMIT OF PERFORMANCE

PERFORMANCE FACTORSPERFORMANCE FACTORS Three Factors That Limit Radius of TurnThree Factors That Limit Radius of Turn

AERODYNAMIC– Occurs when airplane turns at it’s stall velocity

STRUCTURAL– Occurs when aircraft turns at it’s max load limit

POWER– TR cannot overcome induced drag


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.


TAKEOFF & 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


TAKEOFF & 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


Ground Effect Reduces Induced DragGround Effect Reduces Induced Drag:

1.4% @ 1 wingspan

23.5% @ 1/4 wingspan

47.6% @ 1/10 wingspan

PERFORMANCE FACTORSPERFORMANCE FACTORSTAKEOFF & LANDING

During 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


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

DRAG &

FRICTION


TAKEOFF & 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


TAKEOFF & LANDING

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


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 ratio

Increase CLmax

Decrease Vs

Decrease Vlof

Decrease Takeoff Distance

PERFORMANCE FACTORSPERFORMANCE 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 FACTORSPERFORMANCE 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


Forces that comprised acceleration during takeoff are reversed for landings.

Deceleration forces are reversed.

Primary concern is dissipation of kinetic energy.


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


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

REVERSE THRUSTREVERSE THRUST


Aerodynamic 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.


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


TAKEOFF & LANDING

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 aerodynamic braking is most effective--a. During the last half of the landing roll.

b. During the first half of the landing During the first half of the landing roll.roll.c. Throughout the entire landing roll.


TAKEOFF & LANDING

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.


TAKEOFF & LANDINGThe net deceleration force of wheel braking is most effective--

a. During the last half of the landing During the last half of the landing roll.roll.b. During the first half of the landing roll.c. Throughout the entire landing roll.


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


Which deceleration force is the most effective during landing?


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


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


TAKEOFF & LANDING

HYDROPLANING SPEED

TP (9)

INCREASE LANDINGINCREASE LANDING

NO WINDS

NO FLAPS

NO BRAKES

NO REVERSE

HYDROPLANING

HIGH WEIGHT

DECREASE LANDINGDECREASE LANDING

HEADWIND

FULL FLAPS

FULL BRAKING

FULL REVERSE

DRY RUNWAY

LOW WEIGHT

STABILITYSTABILITY

THREE TYPES OF STABILITY

Positive Static Stability

Negative Static Stability

Neutral Static Stability

STABILITYSTABILITY

An 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

STABILITYSTABILITY

POSITITVE STATIC STABILITYPOSITITVE STATIC STABILITY

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

STABILITYSTABILITY

If 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.

STABILITYSTABILITY

If 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.Positive static and positive dynamic stability.

STABILITYSTABILITY

The overall static stability of the aircraft The overall static stability of the aircraft along the longitudinal axis depends on along the longitudinal axis depends on the position of the Center of Gravity the position of the Center of Gravity

( CG) in relation to the Aerodynamic ( CG) in relation to the Aerodynamic Center (AC).Center (AC).

STABILITYSTABILITY

In 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

STABILITYSTABILITY

In 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 CGThe AC must be behind of the CGc. The AC and CG must always be the same

STABILITYSTABILITY

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

a. Symmetrical horizontal stabilizerb. Differential Aileronsc. Dihedral

STABILITYSTABILITY

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

DIHEDRALDIHEDRAL

TORQUETORQUE

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

a. Newton’s first law of motion.b. The coriolis effectc. Newton’s third law of motion.

TORQUETORQUE

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

a. Newton’s first law of motion.b. The coriolis effectc. Newton’s third law of motion.

““P” FACTORP” FACTOR

“P” 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.

““P” FACTORP” FACTOR

“P” 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 during high angles of attack and high power settings.power settings.

SLIPSTREAM ROTATIONSLIPSTREAM ROTATION

Slipstream rotation is caused by the spiraling airflow from the propellers.

a. Trueb. False


Slipstream rotation is caused by the spiraling airflow from the propellers.

a. TrueTrueb. False


The 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.


The pilot must correct for slipstream rotation by--

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

SPINSSPINS

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

SPIN SPIN ONE WING STALLS

YAW BEGINS

ROLL BEGINS

SPIN

SPIN SPIN RECOVERYRECOVERY

POWEROFF

FULLRUDDER

FORWARDYOKE

AILERONSNEUTRAL

RECOVERY

AERODYNAMICSAERODYNAMICS

THE ENDTHE END

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Aerodynamics

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