AERODYNAMICS AERODYNAMICS l l l Bernoullis Principal Lift

AERODYNAMICS

AERODYNAMICS l l l Bernoulli's Principal Lift & Lift Equation Stall & Stall Characteristics Factors Affecting Performance Climbing Performance Gliding Performance l l l Turning Performance Takeoff & Landing Performance Stability Vg Diagram Torque & “P” Factor Spins

BERNOULLI’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 Bernoulli’s principal is best described using which effect? VENTURI EFFECT

BERNOULLI’S PRINCIPAL Concerning the Venturi effect, as the crosssectional area of a tube is reduced, the velocity of the airflow through the tube must-a. Decrease b. Increase c. Remain the same

BERNOULLI’S PRINCIPAL Concerning the Venturi effect, as the crosssectional area of a tube is reduced, the velocity of the airflow through the tube must--

BEROUNILLI’S PRINCIPAL As the velocity of the air moving through a venturi increases-a. Static pressure decreases b. Static pressure increses c. Static pressure is difficult to measure and therefore an increase or decrease is considiered neglible.

BEROUNILLI’S PRINCIPAL As the velocity of the air moving through a venturi increases--

BEROUNILLI’S PRINCIPAL 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.

BEROUNILLI’S PRINCIPAL Static pressure is defined as-- The atmospheric pressure of the air through which an airplane is flying.

BEROUNILLI’S PRINCIPAL 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.

BEROUNILLI’S PRINCIPAL Dynamic pressure is defined as-- The pressure of a fluid resulting from its motion.

LIFT 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.

LIFT Relative 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. True b. False

LIFT Center 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.

LIFT Center 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. True b. False

LIFT 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.

LIFT 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 & balance b. thrust & air density c. 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 1/2 p S V 2 L ~ Lift force CL ~ Coefficient of lift p(rho) ~ density of the air in slugs S ~ total wing area in square feet V ~ airspeed (in feet per second)

DRAG D= CD 1/2 p S V 2 D ~ Drag force CD ~ Coefficient of lift p(rho) ~ density of the air in slugs S ~ total wing area in square feet V ~ airspeed (in feet per second)

DRAG TWO TYPES OF DRAG: – PARASITE – INDUCED

DRAG l PARASITIC DRAG l 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.

DRAG l 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.

DRAG l 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.

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

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

DRAG Total drag is that component of the total aerodynamic force parallel to the ______ that tends to retard the motion of the aircraft. a. chord line b. center of pressure c. relative wind d. none of the above

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

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

STALL & STALL CHARACTERISTICS 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.

STALL & STALL CHARACTERISTICS A 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 airspeed b. density altitude c. 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. True b. False

STALL & STALL CHARACTERISTICS Three reasons why airplane wings are designed to stall root first: l l Impending stall warning over elevator Lessens severity by preventing sudden stall l Allows better lateral control

STALL & STALL CHARACTERISTICS 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.

STALL & STALL CHARACTERISTICS GEOMETRIC TWIST l The twist of an airfoil having different geometric angles of attack at different spanwise locations. l Root has greater angle of incidence than tip l Root operates at an aerodynamically lower of attack.

STALL & STALL CHARACTERISTICS 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.

STALL & STALL CHARACTERISTICS Aerodynamic 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 it’s weight. a. True b. False

STALL & STALL CHARACTERISTICS THE STALL-SPEED EQUATION Vs = 2 W CL p S

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

STALL & STALL CHARACTERISTICS THE STALL-SPEED EQUATION Vs = 2 W CL p S

STALL & STALL CHARACTERISTICS As flaps are lowered, CL MAXIMUM _______. a. Decreases b. Increases c. Becomes Cmax

STALL & STALL CHARACTERISTICS As flaps are lowered, CL MAXIMUM _______. a. Decreases b. Increases c. Becomes Cm

STALL & STALL CHARACTERISTICS THE STALL-SPEED EQUATION Vs = 2 W CL p S

STALL & STALL CHARACTERISTICS 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. True b. False

STALL & STALL CHARACTERISTICS TRUE Vs = 2 n. W Clmax p S

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

STALL & STALL CHARACTERISTICS 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. True b. False

STALL & STALL CHARACTERISTICS TRUE Vs = 2(n. W - T sin a ) Clmax p S

STALL & STALL CHARACTERISTICS THINGS TO REMEMBER ABOUT THRUST l The angle between thrust vector & RW is the AOA l The thrust vector is considered to act along chord l There is a vertical component of thrust that acts parallel to lift and is expressed as T sin a. l L + T sin a - n. W = 0 l The vertical component of thrust reduces stall speed

PERFORMANCE FACTORS Identify the factor that most affects an aircraft’s ability to climb. a. Drag b. Lift c. Excess Power d. Thrust

PERFORMANCE FACTORS Identify the factor that most affects an aircraft’s ability to climb. EXCESS POWER

PERFORMANCE FACTORS During climb, lift operates perpendicular to: a. drag. b. the flight path. c. weight d. thrust

PERFORMANCE FACTORS During climb with the flight path inclined, lift is acting partially rearward resulting in an increase in-a. parasite drag b. profile drag c. induced drag

PERFORMANCE FACTORS 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 thrust d. Both a & b e. Both b & c

PERFORMANCE FACTORS POWER REQUIRED FOR CLIMB T = D + W sin y T ~ Thrust D ~ Drag W ~ Weight sin y ~ angle of climb

PERFORMANCE FACTORS 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

PERFORMANCE FACTORS AFFECTING ANGLE OF CLIMB l ALTITUDE l WEIGHT l WIND

PERFORMANCE FACTORS 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 CEILING TA = TR and sin y = 0

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

PERFORMANCE FACTORS AFFECTING RATE OF CLIMB l ALTITUDE l WEIGHT

PERFORMANCE 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

PERFORMANCE FACTORS AFFECTING RATE OF CLIMB (WEIGHT) – Increase in weight results in increase in HPR. – Increase in weight results in decrease in excess HPA.

PERFORMANCE FACTORS AFFECTING GLIDES An airplane will descend when-a. b. c. d. Weight exceeds lift. Lift exceeds thrust. Thrust exceeds drag. All of the above.

PERFORMANCE 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.

PERFORMANCE FACTORS AFFECTING GLIDES What 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 FACTORS AFFECTING GLIDES

PERFORMANCE FACTORS 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.

PERFORMANCE FACTORS AFFECTING GLIDES Minimum glide angle corresponds to the same angle that will produce-a. Clmax b. Vref c. L/Dmax d. All of the above

PERFORMANCE FACTORS

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

PERFORMANCE FACTORS TURNING FORCES The apparent increase in weight during a turn is caused by which force(s)? a. Centripetal b. Lift c. Centrifugal

PERFORMANCE FACTORS TURNING FORCES During the turn, lift is divided into two components that act at right angles to each other. Vertical Component of Lift Horizontal Component of Lift

PERFORMANCE FACTORS TURNING FORCES The force opposing the vertical component is _____, and the force opposing the horizontal component is _____. a. drag, thrust b. centripetal, centrifugal c. centrifugal, centripetal d. weight, centrifugal

PERFORMANCE FACTORS TURNING 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 l AERODYNAMIC LIMIT OF PERFORMANCE l STRUCTURAL LIMIT OF PERFORMANCE l POWER LIMIT OF PERFORMANCE

PERFORMANCE FACTORS Three Factors That Limit Radius of Turn l AERODYNAMIC – Occurs when airplane turns at it’s stall velocity l STRUCTURAL – Occurs when aircraft turns at it’s max load limit l POWER – TR cannot overcome induced drag

PERFORMANCE FACTORS l Banking an aircraft into a level turn does not change the amount of lift. l Division of lift reduces amount of lift to overcome weight. l Increasing AOA increases total lift and until vertical component equals weight again.

PERFORMANCE FACTORS TAKEOFF & LANDING When 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: Drag l l l 1. 4% @ 1 wingspan 23. 5% @ 1/4 wingspan 47. 6% @ 1/10 wingspan

PERFORMANCE FACTORS TAKEOFF & LANDING During takeoff roll the aircraft must overcome the sum of the horizontal forces in order to accelerate. These forces are: a. Drag b. Friction c. Propeller slippage d. All of the above e. a & b

PERFORMANCE FACTORS TAKEOFF & LANDING During takeoff roll the aircraft must overcome the sum of the horizontal forces in order to accelerate. These forces are: DRAG & FRICTION

PERFORMANCE FACTORS TAKEOFF & LANDING For a given altitude and RPM, the thrust from a propeller-driven airplane ______ as velocity increases during the takeoff roll. a. remains unchanged b. decreases c. increases

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

PERFORMANCE FACTORS TAKEOFF & LANDING l Takeoff distance is directly proportional to takeoff velocity squared. l Takeoff velocity is a function of stalling speed. l Takeoff speed is 1. 2 x Vso

Flaps 40% Improve L/D ratio Increase CLmax Decrease Vs Decrease Vlof Decrease Takeoff Distance

PERFORMANCE FACTORS 1. 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 correct d. only 2 is correct

PERFORMANCE FACTORS TAKEOFF & LANDING l Forces that comprised acceleration during takeoff are reversed for landings. l Deceleration l Primary forces are reversed. concern is dissipation of kinetic energy.

PERFORMANCE FACTORS TAKEOFF & LANDING Residual thrust of the propellers must be overcome during landing. This is overcome with: a. Flaps b. Speed brakes c. Reverse thrust d. Braking

PERFORMANCE FACTORS TAKEOFF & LANDING Residual thrust of the propellers must be overcome during landing. This is overcome with: REVERSE THRUST

PERFORMANCE FACTORS TAKEOFF & LANDING 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.

PERFORMANCE FACTORS 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.

PERFORMANCE FACTORS 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.

PERFORMANCE FACTORS TAKEOFF & LANDING Which deceleration force is the most effective during landing? a. Aerodynamic braking b. Wheel braking (friction) c. Reverse thrust

PERFORMANCE FACTORS TAKEOFF & LANDING Which deceleration force is the most effective during landing?

PERFORMANCE FACTORS TAKEOFF & LANDING The speed at which hydroplaning occurs is dependent upon: a. Flap setting b. Aircraft weight c. Water depth d. Tire pressure e. Tread design

PERFORMANCE FACTORS TAKEOFF & LANDING HYDROPLANING SPEED TP (9)

INCREASE LANDING DECREASE LANDING l NO WINDS l HEADWIND l NO FLAPS l FULL FLAPS l NO BRAKES l FULL BRAKING l NO REVERSE l FULL REVERSE l HYDROPLANING l DRY RUNWAY l HIGH WEIGHT l LOW WEIGHT

STABILITY THREE TYPES OF STABILITY l Positive Static Stability l Negative Static Stability l Neutral Static Stability

STABILITY An object possesses _______ if it tends to return to its equilibrium position after it has been moved. a. positive dynamic stability b. positive static stability c. 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.

STABILITY 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.

STABILITY The 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).

STABILITY 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 CG b. The AC must be behind of the CG c. The AC and CG must always be the same

STABILITY Which of the following methods is employed to improve stability about the longitudinal axis? a. Symmetrical horizontal stabilizer b. Differential Ailerons c. Dihedral

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

TORQUE 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 effect c. Newton’s third law of motion.

“P” 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.

SLIPSTREAM ROTATION Slipstream rotation is caused by the spiraling airflow from the propellers. a. True b. False

SLIPSTREAM ROTATION The pilot must correct for slipstream rotation by-a. Adding left aileron. b. Reducing power on #1 engine c. 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 STALLS YAW BEGINS ROLL BEGINS SPIN

SPIN RECOVERY POWER OFF FULL RUDDER FORWARD YOKE AILERONS NEUTRAL RECOVERY

AERODYNAMICS THE END