Advanced Aerodynamics

1
Advanced Aerodynamics
2
Fundamental Flight Maneuvers

• Straight and Level
• Turns
• Climbs
• Descents

3
Four Aerodynamic Forces

• Lift
• Thrust
• Drag
• Weight
• When are they in equilibrium?

4
Four Aerodynamic Forces

• In steady-state or unaccelerated straight and
  level flight
• What happens when you initiate a climb?

5
Four Aerodynamic Forces

• Lift briefly exceeds weight.
• Rearward component of the Lift adds to drag
• Upward component of Thrust is called the Lift of
  Thrust

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Four Aerodynamic Forces

• Once the climb is established, the forces are
  again balanced

7
Lift

• Which of Newtons laws of motion are used to
  describe lift?

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Lift

• Second law of motion says that a force results
  whenever a mass is accelerated F ma
• Third law states for every action there is an
  equal and opposite reaction

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Bernoullis Principle

• As the velocity of a fluid increase, its internal
  pressure decreases
• High pressure under the wing and lower pressure
  above the wings surface

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Lift

• In what direction does lift act?
• Perpendicular to the relative wind
• Drag acts parallel to the flight path in the
  same direction as the relative wind

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Lift

• Angle of incidence
• Angle of attack
• Washout

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Lift Equation

• L CLV2r/2 S
• If the angle of attack and other factors remain
  constant and airspeed is doubled lift will be
  four times greater

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Controlling Lift

• What are four ways commonly used to control lift?

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Controlling Lift

• Increase airspeed
• Change the angle of attack
• Change the shape of the airfoil
• Change the total area of the wings

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Angle of Attack

• Directly controls the distribution of pressure
  acting on a wing. By changing the angle of
  attack, you can control the airplanes lift,
  airspeed and drag.

16
Angle of Attack

• Angle of attack at which a wing stalls remains
  constant regardless of weight, dynamic pressure,
  bank angle or pitch attitude.

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Angle of Attack

• When the angle of attack of a symmetrical airfoil
  is increased, the center of pressure will remain
  unaffected.

18
Angle of Attack

• At high angle of attack, pressure increases below
  the wing, and the increase in lift is accompanied
  by an increase in induced drag.

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Flaps

• What are the four types of flaps found on general
  aviation aircraft?

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Flaps

• Plain
• Split
• Slotted
• Fowler

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Leading Edge Devices

• Slot
• Slats
• Leading Edge Flaps

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Drag

• Induced drag is a by-product of lift and is
  greatly affected by changes of airspeed.

25
Wing Planform

• Name several wing shapes and their advantages?

26
Wing Planform

• Elliptical - Excellent load distribution for
  high-G maneuvering and low drag for high speeds
• Rectangular - stall first at root, least expensive

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Wing Planform

• Tapered - Favorable stall characteristics with
  good load distribution, saves weight
• Delta - supersonic flight

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Wing Planform

• How do you find the Aspect Ratio of an airplane?

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Wing Planform

• Found by dividing the wingspan by the average
  cord.
• What is a typical aspect ratio for typical
  training aircraft?
• Gliders?

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Wing Planform

• Gliders - 20 to 30
• Training Aircraft - 7 to 9

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Wing Planform

• What is sweep?
• A line connecting the 25 cord points of all the
  wing ribs which is not perpendicular to the
  longitudinal axis of the plane is said to be
  swept
• The sweep can be forward but most are back

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Wing Planform

• What is a device that is used to block or diffuse
  wing tip vortices?

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Wing Planform

• Winglets
• Winglets can increase fuel efficiency at high
  speeds at altitudes by as much as 16 to 26

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Ground Effect

• Where is ground effect found?

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Ground Effect

• Within one wingspan of the ground
• An airplane leaving ground effect will experience
  an increase in what kind of drag?

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Ground Effect

• Induced Drag
• Induced Drag is only about half of its usual
  value when the wing is at 10 of its span above
  the ground

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Drag

• What kind of drags rate of increase is
  proportional to the square of the airspeed?

40
Drag

• What kind of drags rate of increase is
  proportional to the square of the airspeed?
• Parasite Drag
• What kinds of drag make up parasite Drag

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Drag

• Form Drag - based on the shape of the plane, how
  well streamlined and amount of frontal area.

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Drag

• Interference Drag - created when the airflow
  around one part of the airplane interacts with
  the airflow around another.
• Skin Friction Drag - surface friction

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Total Drag

• The sum of the induced drag and the parasite
  drag.
• Total drag is lowest at the airspeed which
  produces the highest ratio of lift to
  drag L/Dmax

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Total Drag

• Best power-off glide range
• Greatest Range

45
High Drag Devices

• Spoilers
• Speed Brakes

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Spoilers

• What are the advantages of using spoilers?

47
Spoilers

• Rapid descent without reducing power, engine
  stays warm
• Maintain normal descent speed
• Help slow to landing gear extension speed
• Descent rapidly through icing
• Stay at high altitudes longer

48
Thrust

• Opposes drag. If greater than drag, the airplane
  is accelerating
• A pound of Thrust must be available for each
  pound of drag.

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Thrust

• Power is the rate at which work is done. It takes
  less power to do the same amount of work at a
  slower rate.

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Propeller Efficiency

• High angle of attack at root, low angle of attack
  at tip
• Elliptical planform
• High Aspect ratio

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Max Level Flight Speed

• Intersection of the Power or Thrust required
  curve with the Power or Thrust available curve.

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Load Factor

• Ratio between the lift generated by the wings at
  any given time divided by the total weight of the
  airplane.

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Load Factor

• What is the relationship between a heavily loaded
  airplane and stall speed compared to a lightly
  loaded airplane?

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Load Factor

• A heavily loaded plane stalls at a higher speed
  than a lightly loaded airplane.
• It needs a higher angle of attack to generate
  required lift at any given speed than when
  lightly loaded.

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Calculating VA

• VA2 VA W2 / W1
• VA2 Maneuvering speed ( at this weight)

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Calculating VA

• VA Maneuvering speed at Maximum weight
• W2 Actual Airplane Weight
• W1 Maximum Weight

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V-G Diagram

• Relates velocity to load factor
• Applies to one airplane type
• Valid for a specific weight, configuration and
  altitude

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Aircraft Stability

• Static Stability
• Dynamic Stability

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Aircraft Stability

• Longitudinal Stability
• Stable in pitch or stable about the lateral axis
• Motion of the plane controlled by the elevators

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Aircraft Stability

• Achieved by locating the center of gravity
  slightly ahead of the center of lift
• Need a tail down force on the elevator

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Aircraft Stability

• Lateral stability
• Return to wings level following a roll deviation
• Dihedral
• Low wing aircraft have more
• Sweep

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Aircraft Stability

• Sweep may be used when dihedral would be
  inappropriate such as in an aerobatic airplane
  that needs lateral stability while inverted

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Aircraft Stability

• Directional Stability
• Vertical tail and sides of the fuselage
  contribute forces which help to keep the
  longitudinal axis aligned with the relative wind.

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Flight Maneuvers

• Straight and Level
• To maintain altitude while airspeed is being
  reduced, the angle of attack must be increased

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Flight Maneuvers

• Climbs
• Transitioning to a climb, angle of attack
  increases and lift momentarily increases
• Thrust acts along the flight path

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Climb Performance

• Decreases with altitude
• Absolute Ceiling
• Service Ceiling

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Turns

• What force turns an airplane?

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Turns

• The horizontal component of lift.
• Load Factor and Turns
• The relationship between angle of bank , load
  factor, and stall speed is the same for all
  airplanes

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Turns

• Rate and radius
• Steeper bank reduces turn radius and increases
  the rate of turn, but produces higher load factors

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Turns

• A given airspeed and bank angle will produce a
  specific rate and radius of turn in any airplane
• Adverse Yaw

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Stalls

• Angle of attack
• Power-on stalls
• Power-off stalls
• Accelerated stall

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Stalls

• Secondary stall
• Cross-controlled stall
• Elevator trim stall

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Stalls

• Total weight, load factor, and CG location affect
  stall speed

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Spins

• Incipient spin
• Fully developed spin
• Spin recovery
• What type of spin can result if the CG is too far
  aft and the rotation is around the CG?

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Spins

• Flat Spin
• Spin Recovery

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Spin Recovery

• Throttle to idle
• Neutralize the ailerons
• Determine the direction or rotation
• Apply full opposite rudder

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Spin Recovery

• Apply forward elevator
• As rotation stops, neutralize the rudder
• Gradually apply aft elevator to return to level
  flight

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One of the main functions of flaps during the
approach and landing is to .
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A. decrease lift, thus enabling a steeper-than-
normal approach to be made. B. decrease the
angle of descent without increasing the
airspeed. C. provide the same amount of lift at
a slower airspeed
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One of the main functions of flaps during the
approach and landing is to C. provide the same
amount of lift at a slower airspeed
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Which is true regarding the use of flaps during
level turns?
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A. The raising of flaps increases the stall
speed. B. The lowering of flaps increases the
stall speed. C. Raising flaps will require
added forward pressure on the yoke or stick.
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Which is true regarding the use of flaps during
level turns? A. The raising of flaps increases
the stall speed.
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A rectangular wing, as compared to other wing
planforms, has a tendency to stall first at the
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A. center trailing edge, with the stall
progression outward toward the wing root and
tip. B. wing root, with the stall progression
toward the wing tip. C. wingtip, with the stall
progression toward the wing root.
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A rectangular wing, as compared to other wing
planforms, has a tendency to stall first at
the B. wing root, with the stall progression
toward the wing tip.
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By changing the angle of attack of a wing, the
pilot can control the airplane's A. lift,
airspeed, and CG. B. lift and airspeed, but not
drag. C. lift, airspeed, and drag.
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By changing the angle of attack of a wing, the
pilot can control the airplane's C. lift,
airspeed, and drag.
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The angle of attack of a wing directly controls
the A. amount of airflow above and below the
wing. B. angle of incidence of the wing. C.
distribution of pressures acting on the wing.
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The angle of attack of a wing directly controls
the C. distribution of pressures acting on the
wing.
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The angle of attack at which a wing stalls
remains constant regardless of
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A. dynamic pressure, but varies with weight,
bank angle, and pitch attitude. B. weight,
dynamic pressure, bank angle, or pitch
attitude. C. weight and pitch attitude, but
varies with dynamic pressure and bank angle.
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The angle of attack at which a wing stalls
remains constant regardless of B. weight,
dynamic pressure, bank angle, or pitch
attitude.
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The need to slow an aircraft below VA is brought
about by the following weather phenomenon
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A. Turbulence which causes a decrease in stall
speed. B. High density altitude which increases
the indicated stall speed. C. Turbulence which
causes an increase in stall speed.
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The need to slow an aircraft below VA is brought
about by the following weather phenomenon C.
Turbulence which causes an increase in stall
speed.
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Stall speed is affected by A. angle of attack,
weight, and air density. B. weight, load
factor, and power. C. load factor, angle of
attack, and power.
98
Stall speed is affected by B. weight, load
factor, and power.
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The stalling speed of an airplane is most
affected by A. variations in airplane
loading. B. variations in flight altitude. C.
changes in air density.
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The stalling speed of an airplane is most
affected by A. variations in airplane loading.
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An airplane will stall at the same
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A. airspeed regardless of the attitude with
relation to the horizon. B. angle of attack and
attitude with relation to the horizon. C. angle
of attack regardless of the attitude with
relation to the horizon.
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An airplane will stall at the same C. angle of
attack regardless of the attitude with relation
to the horizon.
104
In a rapid recovery from a dive, the effects of
load factor would cause the stall speed to A.
not vary. B. increase. C. decrease.
105
In a rapid recovery from a dive, the effects of
load factor would cause the stall speed to B.
increase.
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Recovery from a stall in any airplane becomes
more difficult when its A.elevator trim is
adjusted nosedown. B.center of gravity moves
forward. C.center of gravity moves aft
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Recovery from a stall in any airplane becomes
more difficult when its C.center of gravity moves
aft
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(Refer to figure 2.) Select the correct statement
regarding stall speeds.
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A. Power-off stalls occur at higher airspeeds
with the gear and flaps down. B. In a 60 bank
the airplane stalls at a lower airspeed with the
gear up. C. Power-on stalls occur at lower
airspeeds in shallower banks.
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(Refer to figure 2.) Select the correct statement
regarding stall speeds. C. Power-on stalls
occur at lower airspeeds in shallower banks.
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Refer to figure 2.) Select the correct statement
regarding stall speeds. The airplane will stall
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A. 10 knots higher in a 45 bank, power-on
stall, than in a wings-level stall. B. 10 knots
higher in a power-on, 60 bank, with gear and
flaps up, than with gear and flaps down. C. 25
knots lower in a power-off, flaps-up, 60 bank,
than in a power-off, flaps-down, wings-level
configuration.
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Refer to figure 2.) Select the correct statement
regarding stall speeds. The airplane will
stall B. 10 knots higher in a power-on, 60
bank, with gear and flaps up, than with gear and
flaps down.